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Chapter 9 Cellular Reproduction
Section 1: Cellular Growth
Section 2: Mitosis and Cytokinesis
Section 3: Cell Cycle Regulation
Click on a lesson name to select.
9.1 Cellular Growth
Objectives:
1. Explain why cells are relatively small.
2. Summarize the primary stages of the cell
cycle.
3. Describe the stages of interphase.
9.1 Cellular Growth
Main Idea – Cells grow until they reach their
size limit, then they either stop growing or
divide.
1. Most cells are smaller than the period at
the end of this sentence.
2. The key factor that limits the size of a cell
is the ratio of its surface area to its volume.
3. The surface area of the cell is the area
covered by the plasma membrane.
To calculate the surface area of the cube
multiply L x W x number of sides (6)
4. The volume refers to the space taken up
by the contents of the cell. To calculate
the volume, multiply L x W X H
5. As a cell grows, it’s volume increases
more rapidly than the surface area.
As a cell increases in size the surface
area to volume decreases
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
Ratio of Surface Area to Volume
6. If a cell is too large it may have difficulty
supplying nutrients and expelling waste
products.
7. Cells remain small to maximize the ability of
diffusion and motor proteins to transport
nutrients and waste products.
8. Small cells maintain more efficient transport
systems.
9. The need for signaling proteins to move
throughout the cell also limits cell size.
10. Cell size affects the ability of the cell to
communicate instructions for cellular
functions.
11.Cells reproduce by a cycle of growing and
dividing.
In the cell cycle,
a cell stays in
Interphase the
longest
12.There are three main stages of the cell
cycle interphase, mitosis, and cytokinesis.
Diagram of cell cycle – see pg. 246
Interphase
Longest phase
Cell grows
DNA replication occurs
Mitosis
Nucleus divides
Occurs in 4 stages
Cytokinesis
Shortest phase
Cytoplasm divides
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
 Interphase is the stage during which the
cell grows, carries out cellular functions,
and replicates.
 Mitosis is the stage of the cell cycle during
which the cell’s nucleus and nuclear material
divide.
 Cytokinesis is the method by which a cell’s
cytoplasm divides, creating a new cell.
13. The duration of the cell cycle varies,
depending on the cell that is dividing.
14.For most normal, actively dividing animal
cells, the cell cycle takes approximately
12-24 hours.
15. During interphase, the cell grows, develops
into a functioning cell, duplicates it’s DNA, and
prepares for division.
16.Interphase is divided into 3 stages G1,
S, G2.
17. Chromosomes – contain genetic
material. Chromatin – relaxed form of DNA
in nucleus copies it’s DNA in preparation
for cell division.
18. In mitosis, the cell’s nuclear material
divides and separates into opposite ends of
the cell.
19. In cytokinesis, the cell divides into 2
daughter cells, with identical nuclei.
20. The cell cycle is
the method by which
eukaryotic cells
reproduce
themselves.
21. Prokaryotic cells,
reproduce by a
method called binary
fission.
9.2 Mitosis and Cytokinesis
Objectives:
1. Describe the events of each stage of mitosis.
2. Explain the process of cytokinesis.
Main Idea
Eukaryotic cells reproduce by mitosis,
the process of nuclear division, and
cytokinesis, the process of cytoplasm
division.
Mitosis
1. The key activity of mitosis is the accurate
separation of the cell’s replicated DNA.
2. The process of mitosis increases the
number of cells as a young organism grows
to its adult size.
3. Organisms also use mitosis to replace
damaged cells.
The Stages of Mitosis
4. The 4 stages of mitosis are: prophase,
metaphase, anaphase and telophase.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
The Stages of Mitosis
 Prophase- the first stage of mitosis—cell
spends most of its time here
5. Chromatin tightens or condenses into
chromosomes. This action facilitates chromosome
movement.
6. As prophase continues, the nucleolus seems to
disappear.
7. Microtubule structures called spindle fibers
form in the cytoplasm.
8. Near the end of prophase, the nuclear
envelope disappears.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Metaphase
9. Sister chromatids
are pulled by motor
proteins along the
spindle apparatus
toward the center of
the cell and line up in
the middle, or equator
of the cell.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Anaphase
10. The chromatids are pulled apart.
11. At the end of anaphase, the microtubules,
with the help of motor proteins, move the
chromatids toward the poles of the cell.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Telophase
12. Chromosomes arrive at the poles of the cell
and begin to relax or decondense.
13. Two new nuclear membranes begin to
form and the nucleoli reappear.
• Cytokinesis – process that divides the
cytoplasm
14. This results is 2 cells, each with identical
nuclei.
15. In animal cells, cytokinesis is accomplished
by using microfilaments to constrict or pinch
the cytoplasm.
16. In plant cells, a new structure called a cell
plate forms between two daughter cells. Cell
walls then form on either side of the cell plate.
The 4 Stages of Mitosis
http://www.johnkyrk.com/mitosis.html
Prophase – “poles form” (centrioles)
chromosomes condense; spindle forms
Metaphase – “meet in the middle”
chromosomes line up at the equator
Anaphase – “pull apart”
chromosomes move to opposite poles
Telophase – “pinch together”
nuclear envelope forms; chromosomes decondense
Remember the Stages of Cell Division
I
Probably
Make
A
Teacher
Crazy
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
http://www.johnkyrk.com/mitosis.html
Prokaryotic cells undergo binary fission- cell
divides into 2 genetically identical cells
WHY?
Prokaryotic cells do not have a nucleus.
Mitosis is division of the nucleus.
Binary Fission - lhs.lps.org
2. Mitosis
Prophase
Nuclear membrane disintegrates;
chromosomes condense
Metaphase
Chromosomes attach to spindle and
line up at the equator of cell
Anaphase
Chromosomes move apart to
opposite poles
Telophase
Cell pinches together;
Chromosomes relax
9.3 Cell Cycle Regulation
Objectives:
1. Summarize the role of cyclin proteins in
controlling the cell cycle.
2. Explain how cancer relates to the cell cycle.
3. Describe the role of apoptosis.
4. Summarize the two types of stem cells and their
potential uses.
• Main Idea - The normal cell cycle is regulated
by cyclin proteins.
CELL DIVISION GENES
The rate of cell division varies depending on the
type of cell.
Some cells divide frequently
(some human skin cells divide once/hour)
Some cells divide occasionally
(liver cells divide about once/year)
Some cells don’t divide once they form (nerve
cells)
1. A mechanism involving proteins and
enzymes control the cell cycle.
2. These proteins are called cyclins because
they regulate the timing of the cell cycle in
eukaryotic cells.
3. Cyclins bind to
enzymes called
cyclin-dependent
kinases(CDKs) to
start various activities
that take place in the
cell cycle.
4. Cyclin/CDK combinations occur only during
the stages of interphase and mitosis.
5. Different cyclins/CDK’s combinations control
different activities at different stages in the cell
cycle.
6. The different cyclin/CDK combinations
signal the start of the cell cycle, DNA
replication, protein synthesis, nuclear division
and the end of the cell cycle.
7. The cell cycle also has built in checkpoints
that monitor the cycle and can stop it if
something goes wrong.
Cell Cycle with checkpoints
Chapter 9
Cellular Reproduction
8. Checkpoints occur at the end of G1,
during the S stage, in the G2 stage and
at beginning of mitosis.
Chapter 9
Cellular Reproduction
9.3 Cell Cycle Regulation
9. When cells don’t
respond to the
normal cell cycle
control mechanisms,
a condition called
cancer can result.
10. Cancer is the uncontrolled growth and
division of cells--a failure in the regulation of
the cell cycle.
NO CONTACT INHIBITION
Cancer cells don’t stop
when they touch nearby
cells. . .
they just keep growing!
That’s what makes
a tumor.
http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg
Section 10-3
Control of Cell Division
If center cells are removed,
cells near the space will
start to grow again.
Cells grow until they
touch other cells
Contact Inhibition
SHOWS: Cell division
genes can be turned on
and off
11. When unchecked, cancer cells can kill an
organism by crowding out normal cells,
resulting in the loss of tissue function.
Comparison of Normal and Cancerous
Stomach Cells
12. Cancer cells spend less time in interphase than do
normal cells, which means cancer cells grow and
divide unrestrained as long as they are supplied
with essential nutrients.
• Normal Stomach Cells
– Interphase
– Prophase
– Metaphase
– Anaphase
– Telophase
120 min.
60 min.
10 min.
3 min.
12 min.
•Cancerous Stomach Cells
–Interphase
–Prophase
–Metaphase
–Anaphase
–Telophase
16 min.
15 min.
2 min.
1 min.
3 min.
Cancer cells
• Don’t stop dividing
• Like a “car with no brakes”
• Can spread to new places
(METASTASIS)
http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg
A. Causes of Cancer
13. The changes that occur in the regulation of cell
growth and division of cancer cells are due to
mutation or changes in the segments of DNA
that control the production of proteins.
14. Mutations are permanent changes in a
cell’s DNA; can cause changes in the
growth of a cell leading to cancer.
15. Various environmental factors can affect
the occurrence of cancer cells.
16. Substances and agents that are known to
cause cancer are called carcinogens.
Examples: Ultraviolet light, cigarette
smoke, tobacco, x-rays, asbestos, some
pesticides, arsenic, some viruses,
etc.
B. Cancer genetics
17. More than one
change in DNA
is required to
change an
abnormal cell
into a cancer
cell.
18. The risk of cancer increases with age.
Because, number of mutations increases
with age.
19. The fact that multiple changes must occur
also might explain why cancer runs in
some families
20. When an embryo divides, some cells go
through a process called apoptosis, or
programmed cell death.
21. Examples of apoptosis occur during
the development of human hand and
foot; in plants, leaves falling from trees
during autumn.
22. Apoptosis also occurs in cells that are
damaged beyond repair including cells
with DNA damage that could lead to
cancer.
Stem cells –
23. The majority of cells in a multicellular
organisms are designed for a specialized
function.
24. Stem cells are unspecialized cells that can
develop into specialized cells; 2 types
Adult stem cells and
Embryonic stem cells
• Possible uses for stem cells
Embryonic stem cells
25. An embryo results from the fertilization of
an egg by a sperm. These unspecialized
cells are embryonic stem cells.
26. Embryonic stem cells research is
controversial because of ethical concerns
about the source of the cells.
27. Ethics are values in society that consider
the rightness or wrongness of certain actions
Adult stem cells
28. Adult stem cells are found in various
tissues in the body and might be used to
maintain and repair the same kind of tissue in
which they are found.
29. Research with adult stem cells is much
less controversial because the adult stem cells
can be obtained with the consent of their
donor.