Transcript Cell Size Limits

Cell Size
Surface area : Volume
Ch 8.2 pg 201
Cell Size Limits
Are whale cells the same size as
sea stars cells?
Yes!
Cell Size Limitations
Getting things into cell at an efficient rate
– Nutrients
– Water
– Oxygen
Removing things from the cell quickly
– wastes
DNA limits cell size
– If cell is too big then DNA cannot make
enough proteins to support the cell
What limits the size of cells?
Surface Area to Volume Ratio - How much space is on the
outside (cell membrane) compared to the space on the inside of the
cell.
As the surface area of something increases, it’s volume increases
faster
Surface area = L x W x # of sides (cm2) the surface of an
object. The outside covering of a cell. (cell membrane)
Volume = L x W x H (cm3)
The space inside the cell
A small object has a high surface area to volume ratio ex: 6/1
A large object has a small surface area to volume ratio ex: 24/8
Large Cell
It takes more
time for the
nutrients to
reach the
center of this
cell
Smaller cell
It takes less
time for the
same nutrients
to reach the
center of this
cell
Answers
1. As a cell gets larger which increases at a faster rate,
the surface area or the volume?
Volume
2. If a cell were larger, would it’s interior structures be
closer or further from the cell membrane?
Further
3.
What problems might occur if cells were too large?
Not enough nutrients in fast enough
Conclusion
As cell size increases, the surface area to
volume ratio Decreases (small surface area
to volume ratio), which can lead to death of
a cell.
Having a large surface area to volume
ratio is important to the functioning of cells
since it gets materials, nutrients, O2, &
wastes into & out of it faster.
Cells divide before they get too big!