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?
Go to
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:
Section 10-1
There are 2 main reasons why cells divide rather
than growing larger:
1. DNA “Overload”-when a cell is small, the
information stored in that DNA meets the needs
of the cell; as a cell grows it usually does not
make extra copies of DNA which created an
information shortage.
ex. Small town library
Go to
Section:
Section 10-1
2.
Material Exchange-all food, water, oxygen and
wastes must pass through the cell membrane.
The rate at which this exchange takes place
depends on the surface area of the cell.
Ratio of Surface Area to VolumeVolume increases much more rapidly than the
surface area, causing the ratio of surface area
to volume to decrease.
ex. Main street
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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:
Section 10-1
Division of the Cell
The process by which a cell divides into 2 new
daughter cells.
Before the cell divides, DNA replication takes place.
These processes allow the cells to:
a. Reduce volume
b. Increase surface area to volume ratio
c. Maintain available genetic information
Go to
Section:
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?
Go to
Section:
Section Outline
Section 10-2
10–2 Cell Division
A. Chromosomes
B. The Cell Cycle
C. Events of the Cell Cycle
D. Mitosis
1.Prophase
2.Metaphase
3.Anaphase
4.Telophase
E. Cytokinesis
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Section:
Video 1
Section 10-2
Chromosomes-are comprised of DNA and protein.
These carry the genetic information in
eukaryotic cells. Only visible during cell
division.
Before cell division, each chromosome is
replicated, creating identical “sister”
chromatids. During cell division each
chromatid will go to the 2 new cells.
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Section:
Section 10-2
Cell Cycle1. Cell grows
2. Prepares for division
3. Divides to form 2 daughter cells
4. Daughter cells begin cycle again
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Section:
Figure 10–4 The Cell Cycle
Section 10-2
G1 phase
M phase
S phase
G2 phase
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Section:
Section 10-2
Interphase
This phase consists of:
G1 phase-main growth of a cell
S phase- DNA replicated
G2 phase-many organelles and
molecules required for cell
division are produced
Go to
Section:
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
Section 10-2
Mitosis
part of eukaryotic cell division in which the
nucleus divides
Lasts a few minutes to several days.
Four phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
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Section:
Section 10-2
Prophase
This is the first and longest phase.
Events that take place include:
1. chromosomes become visible
2. centrioles separate and move to
opposite sides
3. spindle (fan-like microtubule
structure) forms
4. chromosomes attach to spindle
fibers
Go to
Section:
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
Section 10-2
Metaphase
Second phase of mitosis
Events that take place include:
1. chromosomes line up in the
center of the cell
2. microtubules connect the
centromere of each
chromosome to the two poles
of the spindle
Go to
Section:
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
Section 10-2
Anaphase
Third phase of mitosis
Events that take place include:
1. the centromeres that join the
sister chromatids split allowing
the sister chromatids to
become individual
chromosomes
2. chromosomes move towards the
ends of the cell
Go to
Section:
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
Section 10-2
Telophase
Fourth and final phase of mitosis
Events that take place include:
1. chromosomes are at opposite
ends of cell and lose shape
2. two new nuclear envelopes will
form around the chromosomes
Go to
Section:
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
Section 10-2
Cytokinesis
Animal cells-cell membrane is drawn
inward until the cytoplasm is pinched into
2 equal parts
Plant cells-a cell plate forms midway
between the divided nuclei. This
eventually becomes a cell membrane and
a cell wall.
Go to
Section:
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
Concept Map
Section 10-2
Cell Cycle
includes
Interphase
M phase
(Mitosis)
is divided into
is divided into
G1 phase
Go to
Section:
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
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
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Section:
Different types of cells go through the cell cycle
at different rates.
Contact Inhibition
- in normal tissues cells stop dividing when
they come into contact with other cells
- when contact is lost they begin dividing again
- ex.: cut in your skin
Go to
Section:
Control of Cell Division
Section 10-3
Go to
Section:
Cyclins are chemicals that cells produce which
regulate the timing of the cell cycle in eukaryotic
cells.
The sample is injected
into a second cell in G2
of interphase.
A sample of
cytoplasm
is removed
from a cell
in mitosis.
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Section:
As a result, the second
cell enters mitosis.
Internal regulators – proteins that respond to
events inside the cell and allow the cell cycle to
proceed or not.
- produced only when all DNA is replicated
- controls until all chromosomes attached
to spindle fibers
External regulators – proteins that respond to
events outside the cell.
- growth factors and surface receptors
Go to
Section:
Uncontrolled Cell Growth = Cancer
- cancer cells do not respond to normal controls
- divide uncontrollably and form masses of cells
called tumors
- cells may metastasize – break loose from
tumor and spread
- mutations in a gene called p53 are often what
triggers cancer
Go to
Section:
Stem Cells – unspecialized cells which can give
rise to other cell types.
- in an embryo there are many stem cells which
will give rise to the specialized cells of your
body
- adult stem cells are present, but harder to find
- medical research is trying to use stem cells to
cure disease.
Go to
Section:
Figure 10–8 Effect of Cyclins
Section 10-3
Go to
Section:
Video 2
Animal Cell Cytokinesis
Click the image to play the video segment.
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.
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