1. REGULATING the CELL CYCLE

2. Control of Cell Division
Section 10-3
If center cells are removed, cells near the space will start to grow again.
SHOWS: Cell division
genes can be turned on
and off
Cells grow until they touch other cells

3. CELL DIVISION GENES
EXAMPLE: Cell division genes can be ________ in case of injury.
Cells near injury are
stimulated to divide
to heal and replace damaged/missing cells
and shut off when the
repair has been made.
turned on

4. CELL DIVISION GENES 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)

5. CELL CYCLE REGULATORS
In early 1980’s scientists discovered a protein in dividing cells that caused a
______________to form in
_______________ cells
Mitotic spindle
NON-dividing
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6. CELL CYCLE REGULATORS Levels of this protein rose and fell with
the cell cycle so it was named
__________ because it seemed to control the cell cycle.
A whole family of CYCLINS have since been discovered that regulate the _____________________
in EUKARYOTIC CELLS
CYCLIN
TIMING of CELL CYCLE
Pearson Education Inc; Publishing as Pearson Prentice Hall

7. OTHER REGULATORS INTERNAL
______________ REGULATORS Proteins that respond to events inside
the cell.
Allow cell cycle to proceed only if
certain processes have happened
EX: Cell can’t enter mitosis until all the
chromosomes have been copied

8. OTHER REGULATORS EXTERNAL
______________ REGULATORS Proteins that respond to events outside
the cell.
Signals tell cell to speed up or slow
down the cell cycle
EX:
Growth factors stimulate cells to divide Especially important during wound healing and
embryo development

9. EXTERNAL REGULATORS Molecules on the surface of neighboring
cells act as signals to slow down
or stop the
cell’s cycle.
These signals prevent
excessive growth and
keep tissues from
disrupting each other.
Pearson Education Inc; Publishing as Pearson Prentice Hall

10. Cancer cells have lost control of their cell division genes
SEM Image by: Riedell
CHO (Chinese Hamster Ovary) cells in culture

11. NO CONTACT INHIBITION Cancer cells don’t stop when they touch nearby
they just keep growing!
That’s what makes
a tumor.
See a video

12. Cancer cells Carcinogens Don’t stop dividing
Like a “car with no brakes”
Can spread to new places (METASTASIS)
______________ are substances that can damage DNA and cause cancer
Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses,
Carcinogens

13. Cancer cells
Cancer is complicated and can have many causes, but all cancers have one thing in common . . .…
They have lost control over their _____________.
Many cancers cells have a damaged or defective
gene called _____, so they can’t respond to
normal cell signals to control their growth.
CELL CYCLE
p53

14. UNCONTROLLED CELL GROWTH
Cancer-disorder in which some of the body’s own cells lose the ability to control growth
Cancer cell do not respond to the signals that regulate the growth of most cells, the divide uncontrollably and form masses of cell called tumors that can damage, surrounding tissue
Two types of tumors
Benign-Does not spread to surrounding tissue (non-cancerous)
Malignant-spreads and destroys healthy tissue (cancerous)

15. CANCER CONTINUED Causes Biological Agent-Viruses
Chemical Agent-Carcinogens-tobacco
Physical Agent-radiation
*Treatments
* Surgery
* Radiation
* Chemotherapy-aimed at fast growing cells

16. How Cancer Begins Page 12
Changes in genes that influence the cell cycle can cause the transformation of a normal cell into a cancer cell.
Two types of these genes
The first type codes for proteins that stimulate cell division; these are usually turned-off in non-dividing cells
They become ONCOGENES (cancer gene) by mutation
A common oncogene, ras, is present in mutated form in about 30 % of human cancers and in some forms of leukemia 16

17. Page 12 Continued
The second type of gene associated with cancer is a TUMOR SUPPRESSOR GENE
These code for proteins that normally restrain cell division
In cancer tumor suppressor genes have been inactivated by mutation
An inherited mutation in one copy of a tumor suppressor gene results in higher risk of cancer 17

18. Page 12 Continued
Almost 50% of human cancers are associated with a mutation in the tumor suppressor gene p53
P53 protein normally acts as an emergency brake in the cell cycle, but when mutated does not prevent unchecked cell division
Cancers include breast, colon, lung, prostate, and skin 18

19. Surviving Cancer Page 13
In the United States, about one of every five deaths-more than half a million each year-are caused by cancer. (Only heart disease kills more)
Lung cancer is the number one cancer killer
Colorectal, breast and prostate are the next most common
Cancer survival is measured by the percentage of cancer patients who survive a specific number of years. 19

20. Page 13 Continued
Cancer survival is influenced by the type of cancer and by the stage at which a cancer is diagnosed
Cancers range from Stage 1, early onset of cancer to Stage 4, the most advanced cancer
EX: Colorectal cancer Stage 1, 5-yr survival rate is 96%; Stage 4 colorectal cancer 5-yr survival rate is 5%
Pancreas cancer 5-yr rate is only 4%
All cancers have a 64% 5-yr survival rate 20

21. ANTI-SMOKING commercial

22. SOUTH DAKOTA CORE SCIENCE STANDARDS
LIFE SCIENCE: Indicator 1: Understand the fundamental structures,
functions, classifications, and mechanisms found
in living things
9-12.L Students are able to relate cellular functions and processes to specialized structures within cells.
Cell life cycles (ANALYSIS)
Examples: somatic cells (mitosis)

23. Core High School Life Science Performance Descriptors
High school students performing at the
ADVANCED level:
predict the function of a given structure;
predict the outcome of changes in the cell cycle;
PROFICIENT level:
describe the relationship between structure and function
compare and contrast the cell cycles in somatic and germ cells;
BASIC level
recognize that different structures perform different functions
describe the life cycle of somatic cells;