3. Read pages 350 & 351 together as a class.
TEXTBOOK READING TIME!
4. Discuss the two types of proteins that regulate the cell
cycle. How do they work?
TURN AND TALK!
5. CONTROL OF THE CELL CYCLE
The cells of some tissues divide frequently throughout their
lifespan.
e.g., skin, intestine
Cell division occurs rarely, or not at all, in other tissues.
e.g., brain, heart, skeletal muscles
Cell division in eukaryotes is driven by enzymes and
controlled at specific checkpoints.
Enzymes – special regulatory proteins used by the cell
control the rate of chemical reactions and are used to
monitor a cell’s progress from phase to phase during the
cell.
6. REGULATORY PROTEINS
There are two types of proteins that regulate the cell cycle.
Internal regulators allow the cell cycle to proceed
certain events have occurred.
External regulators speed up or slow down the cycle.
7. CHECKPOINTS OF THE CELL CYCLE
Although enzymes drive the cell cycle, multiple checkpoints
ensure that:
the cell successfully completes DNA synthesis during
interphase.
proper chromosome movements occur during mitotic
cell division.
8. CHECKPOINTS OF THE CELL CYCLE
G1 to S
Ensures that the cell’s
DNA is suitable for
replication. Triggers
cell death (apoptosis)
if damage can’t be
repaired.
9. CHECKPOINTS OF THE CELL CYCLE
G2 to Mitosis
Ensures that DNA has
been completely and
accurately replicated.
Chromosomes remain
extended and
accessible to DNA
Repair Enzymes,
which fix DNA before
cell enters Mitosis.
10. CHECKPOINTS OF THE CELL CYCLE
Metaphase to Anaphase
Ensures that the
chromosomes area
aligned properly at the
metaphase plate.
11. Read page 352 together as a class.
TEXTBOOK READING TIME!
12. Discuss the two ways cells end their life cycle. Describe
apoptosis and the role it plays in the development of
organisms.
TURN AND TALK!
13. APOPTOSIS
Cells end their life cycle in one of
two ways:
A cell may die by accident due
to damage or injury.
A cell may actually be
“programmed” to die.
Apoptosis is a process of
programmed cell death; it
plays a key role in
development by shaping the
14. Read page 353 & 354 together as a class.
TEXTBOOK READING TIME!
16. CANCER
Occasionally, cells lose control of the cell
cycle and do not respond to the signals
that regulate the growth of most cells.
They continue to divide when healthy cells
would stop.
Cancer is defined as the uncontrolled
and division of cells that results from a
failure in the regulation of the cell cycle.
Cancer is the second leading cause of
death in the United States.
18. CANCER
Cancerous cells form masses of tissue called tumors that
deprive normal cells of nutrients.
Benign are noncancerous tumors that do not spread to
surrounding healthy tissue or to other parts of the body.
Malignant tumors are cancerous and will invade and
surrounding healthy tissue.
20. CANCER
Both genetic and environmental factors
are involved in causing cancer. Substances
and agents that are known to cause cancer
are called carcinogens.
Genetic Factors center around changes
DNA. More than one change in DNA is
required to change an abnormal cell
into a cancer cell.
Environmental Factors include where
live, cigarette smoke, air and water
21. CANCER PREVENTION
Diets high in fiber, low in fat
Fruits and vegetables and grains
Vitamins A, C, E, and Calcium
Carotenoid containing foods
Daily exercise
Avoid using tobacco
Editor's Notes
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Growth factors, for example, stimulate growth and division; these are especially important during embryonic development and wound healing.
Would want to slow the cycle to prevent excessive cell growth and to keep body tissues from disrupting one another.
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Cancer is the second leading cause of death globally, and is responsible for an estimated 9.6 million deaths in 2018. Globally, about 1 in 6 deaths is due to cancer.
Heart disease and stroke take the lead!
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So how are the growth of a tumor and the repair of a scrape on your knee similar? How are they different? They are similar because the both involve rapid cell division. They are different because once a scrape is repaired, the rapid cell division will stop; however, in a tumor the rapid cell division does not stop.
