Eukaryotic Cell Size Why are most eukaryotic cells between 10 and 100 m in diameter? How big is that? Remember 1 mm is the.
Download ReportTranscript Eukaryotic Cell Size Why are most eukaryotic cells between 10 and 100 m in diameter? How big is that? Remember 1 mm is the.
Slide 1
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 2
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 3
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 4
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 5
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 6
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 7
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 8
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 9
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 10
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 11
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 12
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 13
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 14
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 2
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 3
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 4
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 5
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 6
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 7
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 8
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 9
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 10
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 11
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 12
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 13
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.
Slide 14
Eukaryotic Cell Size
Why are most eukaryotic cells
between 10 and 100 m in diameter?
How big is that?
Remember 1 mm is the smallest mark on a
metric ruler.
1
2
Remember it takes 1000 micrometers (m)
to equal 1 millimeter (mm).
1
2
Eukaryotic cells are microscopic
Answer:
10-100 m = 0.01 -
0.1
mm
In other words, one cell is smaller than
1 millimeter. The largest of eukaryotic cells
are 1/10 of a mm in diameter (0.1 mm)!
1
2
Certainly we have small and
large eukaryotic organisms
(Think of an amoeba, a mouse and a redwood tree).
Why don’t we find smaller and larger
eukaryotic cells to match?
What keeps cells from getting
smaller than 10 micrometers?
This is what we call the LOWER LIMIT on cell
size.
It is related to the minimum amount of space it
would take to hold all the essential cell
structures.
If you try to make a cell smaller than 10 m,
something essential would not fit and therefore
the cell would not survive.
What keeps cells from getting
larger than 100 micrometers?
This is what we call the UPPER LIMIT on
cell size.
This is related to the ability of the cell to
supply its metabolic needs.
Metabolic Needs
Volume
To survive a cell must
have sufficient nutrients
and gases for its size.
A cell’s metabolic needs
are defined by its
volume*. The larger the
cell the greater its
metabolic needs will be.
*
Volume refers to the internal space of a
cell. By analogy, a box’s volume refer
to how much “stuff” it could hold.
Needs
Supplying those Needs
Nutrients
Wastes
Gases
Everything that enters and
leaves a cell must come
through its cell membrane.
This would include nutrients,
gases and wastes.
To supply its needs a cell
must have enough surface
area* to get those needed
materials in and wastes out
quickly.
*
Surface area refers to the covering
of a cell. By analogy, a box’s
surface area could be measured by
the amount of wrapping paper it
would take to cover it completely.
Surface Area to Volume Ratio
To meet its metabolic needs, a cell must have
sufficient surface area for its volume. This
relationship is described as a “large surface area to
volume (SA/V) ratio.”
In other words, a cell must have enough cell
membrane to be able to transport what it needs in
and out at a fast enough rate to survive. The ratio
of the two is critical.
What happens as a cell grows?
SA
V
As a cell grows, its surface area (SA) increases.
As a cell grows, its volume (V) increases.
So what’s the problem?
If both the SA (supply) and V (needs/demand) increase
with increasing cell size, why can’t a cell grow as large as
it wants?
The problem is that while both SA and V increase, they
don’t grow at the same rate. The volume (V = needs)
increases faster than the surface area (SA= supply).
SA
V
Therefore, the SA/V ratio actually
decreases with increasing cell size.
SA / V
Remember cells need a large SA/V ratio.
And, the larger the cell the smaller that ratio
will be.
The decreasing SA/V ratio
limits cells from growing
larger than 100 m.
Without enough surface area for its
size, such a large cell will not be able
to supply its own needs.
It is all about supply and demand
As cells grow larger, while both the supply
and demand increase, the “needs” quickly
outpace the “supply.”
At that point, the cell must stop growing or
divide into two smaller cells or it will die.
Without the ability to supply its own needs,
the cell would either have insufficient
energy to live or poison itself with its own
wastes.