Transcript Prentice Hall Biology

Interest Grabber
Section 10-1
Getting Through
Materials move through cells by diffusion. Oxygen and food move into
cells, while waste products move out of cells. How does the size of a cell
affect how efficiently materials get to all parts of a cell?
Work with a partner to complete this activity.
1. On a sheet of paper, make a drawing of a cell that has the following
dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell
about one half the size of your cell on a separate sheet of paper.
2. Compare your drawings. How much longer do you think it would take
to get from the cell membrane to the center of the big cell than from the
cell membrane to the center of the smaller cell?
3. What is the advantage of cells being small?
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Section:
Section Outline
Section 10-1
10–1
Cell Growth
A. Limits to Cell Growth
1. DNA “Overload”
2. Exchanging Materials
3. Ratio of Surface Area to Volume
4. Cell Division
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Section:
Read paragraph 1, p. 241
Cell Growth
Growth in multi-cellular organisms
is due mostly to increase in cell
numbers, not an increase in cell
size.
To increase the number of cells, cells
need to DIVIDE
See p. 246
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Section:
Two reasons why cells need to divide
instead of growing larger:
1. The larger the cell, the more
demands are placed on the cell’s DNA.
2. Cells have trouble moving
nutrients and wastes across the cell
membrane.
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Section:
DNA “Overload”
In a normal sized cell, DNA is
easily able to control cell functions.
When a cell increases in size, more
DNA is NOT produced
A large cell would have a hard time
functioning with limited DNA
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Section:
Material Exchange
Food, water, O2, etc. enter a cell
through the cell membrane.
Waste products leave the same way.
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Section:
Material Exchange
The rate of exchange depends on
the surface area of the cell.
The rate at which food and O2 are
used up and waste produced
depends on the cell’s volume.
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Section:
Ratio of Surface Area to Volume
An understanding of this ratio is
needed to appreciate why cells
divide instead of growing larger
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Section:
Ratio of Surface Area to Volume
Imagine that a cell is cubed shape
Surface Area = L x W x # of sides
Volume = L x W x H
Ratio =
Surface Area
Volume
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Section:
Ratio of Surface Area to Volume
What is the surface area of a cube
that has a length of 1cm?
Surface Area = L x W x # of sides
1 cm x 1 cm x 6 sides = 6 cm2
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Section:
Ratio of Surface Area to Volume
What is the volume of a cube that
has a length of 1cm?
Volume = L x W x H
1 cm x 1 cm x 1 cm = 1 cm3
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Section:
Ratio of Surface Area to Volume
Surface Area
6
Volume
1
In other words, there 6 units of
surface area to each unit of volume
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Section:
doubles in
What if the cell
size?
2 cm x 2 cm x 6 sides = 24 cm2
2 cm x 2 cm x 2 cm = 8 cm3
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Section:
24
3
8
1
With a 3 : 1 ratio, there are now 3
units of surface area to each unit of
volume
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Section:
What if the cell
triples in
size?
3 cm x 3 cm x 6 sides = 54 cm2
3 cm x 3 cm x 3 cm = 27 cm3
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Section:
54
2
27
1
With a 2 : 1 ratio, there are now 2
units of surface area to each unit of
volume
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Section:
Ratio of Surface Area to Volume
As a cell grows in size, the cell’s
volume increases more rapidly than
the surface area.
In other words, the SA : Vol ratio
decreases = serious problems for
the cell
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Section:
too large
If the cell becomes
,
it is very difficult for the cell to have
necessary products move in and
out of the cell
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Section:
Ratio of Surface Area to Volume in Cells
Section 10-1
Cell Size
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
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Section:
Cell Division
During cell division, the cell divides
into 2 new cells before the cell
becomes too large.
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Section:
Cell Division
During cell division…
1. DNA replicates to assure that
each new daughter cell receives
genetic information
2. Each daughter cell has an
increased SA : Vol ratio to allow
the cell to function efficiently
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Section:
Interest Grabber
Section 10-2
Cell Cycle
The cell cycle represents recurring events that take place in the period of
time from the beginning of one cell division to the beginning of the next. In
addition to cell division, the cell cycle includes periods when the cell is
growing and actively producing materials it needs for the next division.
1. Why is the cell cycle called a cycle?
2. Why do you think that it is important for a cell to grow in size during its
cell cycle?
3. What might happen to a cell if all events leading up to cell division took
place as they should, but the cell did not divide?
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Section:
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Section:
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Section Outline
Section 10-2
10–2 Cell Division
C.
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Section:
A. Chromosomes
B. The Cell Cycle
Events of the Cell Cycle
D. Mitosis
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
E. Cytokinesis
Cell Division
Goals:
Main events of the cell cycle
Four phases of mitosis
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Section:
Purpose of Cell Division
 Asexual reproduction of some
organisms
 Source of new cells as a multicellular organism grows and
develops
 Source of replacement cells
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Section:
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Section:
Cell Division
Before a cell divides , it needs to
prepare itself to assure that each
new daughter cell gets a complete
set of information.
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Section:
Cell Division
In eukaryotes, cell division occurs
in two stages:
Mitosis
Nucleus divides
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Section:
Cytokinesis
Cytoplasm divides
Chromosomes
Made of DNA and proteins
Carries the cell’s coded genetic
information
There is a specific number of
chromosomes, depending on the
organism
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Section:
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Section:
Chromosome Structure
Chromosomes are only visible during
cell division when they are
condensed.
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Section:
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Section:
Chromosome Structure
Chromosomes are replicated before cell
division.
After replication, each chromosome now
consists of two identical sister chromatids.
Why?
One chromatid goes to each of the two new
cells, and each cell must receive the same
genetic information.
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Section:
Chromosome Structure
Each pair of chromatids is attached at
an area called the centromere (central
part).
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Section:
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Section:
The Cell Cycle
The cell cycle is a series of events
that cells go through as they grow
and divide.
During the cell cycle, a cell grows,
prepares for division, and divides to
form two daughter cells, each which
then begins the cycle again.
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Section:
Concept Map
Section 10-2
Cell Cycle
includes
G1 phase
Interphase
M phase
(Mitosis)
is divided into
is divided into
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Figure 10–4 The Cell Cycle
Section 10-2
G1 phase
M phase
S phase
G2 phase
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Section:
Mitosis
What is the goal of mitosis?
To evenly divide the genetic
information that is found in the
nucleus.
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Section:
Cytokinesis
What is the goal of cytokinesis?
To divide the cytoplasm, which
contains the nucleus and other
structures, into two equal parts.
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Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
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Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
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Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
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Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Interest Grabber
Section 10-3
Knowing When to Stop
Suppose you had a paper cut on your finger. Although the cut may have
bled and stung a little, after a few days, it will have disappeared, and your
finger would be as good as new.
1. How do you think the body repairs an injury, such as a cut on a
finger?
2. How long do you think this repair process continues?
3. What do you think causes the cells to stop the repair process?
Go to
Section:
Section Outline
Section 10-3
10–3
Regulating the Cell Cycle
A. Controls on Cell Division
B. Cell Cycle Regulators
1. Internal Regulators
2. External Regulators
C. Uncontrolled Cell Growth
Read p. 250
See p. 249
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Section:
Hyperlink slide 74
Regulating the Cell Cycle
Goals:
How is the cell cycle regulated?
What are cancer cells?
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Section:
What regulates the cell cycle?
Hunt and Kirschner Research of the
1980s
Removed a sample of cytoplasm from a
dividing cell.
Injected the sample into a non-dividing cell.
The non-dividing cell entered into cell
division.
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Section:
Figure 10–8 Effect of Cyclins
Section 10-3
The sample is injected
into a second cell in G2
of interphase.
A sample of
cytoplasm
is removed
from a cell
in mitosis.
As a result, the second
cell enters mitosis.
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Section:
What regulates the cell cycle?
The researched refined the
cytoplasm of the dividing cell and
isolated an important protein…
CYCLIN
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Section:
Cyclin regulates the timing of the cell
cycle in eukaryotic cells.
In addition, many other types have
been discovered that also regulate
the cell cycle.
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Section:
Cell regulators can be divided into
two groups…
Internal and External Regulators
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Section:
Internal Regulators
Specialized proteins that respond to
events inside of the cell.
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Section:
Internal Regulators
These regulators allow the cell cycle
to proceed only when certain
processes have been completed.
 All chromosomes must be replicated
 All chromosomes are attached to a
spindle fiber
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Section:
External Regulators
Specialized proteins that respond to
events outside of the cell.
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Section:
Control of Cell Division
Section 10-3
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Section:
External Regulators
These protein regulators direct the
cell to speed up or slow down the
cell cycle, i.e. growth factors.
 Important for embryonic
development and wound healing.
 Other growth factors keep cells
from overproducing
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Section:
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Section:
Uncontrolled Cell Growth
Cell growth is regulated because
uncontrolled growth can have severe
consequences.
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Section:
Uncontrolled Cell Growth
Cancer cells do not respond to the
signals that regulate the growth of
most cells.
 Cancer cells divide uncontrollably
 Cancer cells can form masses of
cells…tumors
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Section:
Aging Skin
1.
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Section:
www.youtube.com/watch?v=py9C4a8ky8o
http://www.syracuse.com/have-youheard/index.ssf/2011/05/viral_video_of_the_
day_dear_16-year-old_me.html
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Section:
Tumors – masses of cells
Benign and Malignant
 Can damage surrounding tissues
 Cancer cells can break loose from
tumors and spread throughout the
body.
Go to
Section:
Cancer – A Disease of the Cell
Cycle
Many things can cause cancer carcinogens
Tobacco products, radiation (solar
and nuclear), viral infections
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Section:
Videos
Click a hyperlink to choose a video.
Animal Cell Mitosis
Animal Cell Cytokinesis
Video 1
Animal Cell Mitosis
Click the image to play the video segment.
Video 2
Animal Cell Cytokinesis
Click the image to play the video segment.
Go Online
Links on cell growth
Links from the authors on stem cells
Share cell cycle lab data
Interactive test
For links on cell division, go to www.SciLinks.org and enter the Web
Code as follows: cbn-3102.
For links on the cell cycle, go to www.SciLinks.org and enter the Web
Code as follows: cbn-3103.
Interest Grabber Answers
1. On a sheet of paper, make a drawing of a cell that has the following
dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell
about one half the size of your cell on a separate sheet of paper.
2. Compare your drawings. How much longer do you think it would take
to get from the cell membrane to the center of the big cell than from the
cell membrane to the center of the smaller cell?
It would take twice the amount of time.
3. What is the advantage of cells being small?
If cells are small, materials can be distributed to all parts of the cell quickly.
Interest Grabber Answers
1. Why is the cell cycle called a cycle?
It represents recurring events.
2. Why do you think that it is important for a cell to grow in size during its cell
cycle?
If a cell did not grow in size, each cell division would produce progressively
smaller cells.
3. What might happen to a cell if all events leading up to cell division took
place as they should, but the cell did not divide?
Students may infer that a cell that undergoes all sequences of the cell
cycle would grow increasingly larger—to a point at which the cell could no
longer exchange materials with the environment efficiently enough to live.
Interest Grabber Answers
1. How do you think the body repairs an injury, such as a cut on a finger?
The cut is repaired by the production of new cells through cell division.
2. How long do you think this repair process continues?
Cell division continues until the cut is repaired.
3. What do you think causes the cells to stop the repair process?
Students will likely say that when the cut is filled in, there is no room for
more cells to grow.
This slide is intentionally blank.