Transcript Control of Cell Division 13

Biology – The Building
Blocks of Life

Objectives:
– Describe normal cell growth and
its limits
– Define the causes and effects of
cancer
Limits for Cell Growth
– A cell has one set of DNA
 TRUE
– One set of DNA can regulate a cell that is any
size
 FALSE – one set of blueprints is NOT enough
to build the biggest building
Limits for Cell Growth
– All nutrients & waste pass through the
cell membrane
 TRUE
– When a cell’s inside volume double, so
too does the outside surface area
 FALSE
 The internal volume of a cell grows
faster than the outside boundary
(membrane)
Surface to Volume Ratio
Break
apart
Grow
Radius
Surface
4pr2
Volume
4/3pr3
S/V
Ratio

1.0

3.0

1.0

12.6

113.1

339.4

4.2

113.1

113.1

3

1

3
Limits for Cell Growth
(continued)
– A larger cell has a hard time getting nutrient
in and waste out of the cell
 TRUE
– A cell undergoes division to solve its size
problems
 TRUE
Controls of Cell Growth

Muscle and Nerve cells do not
divide…EVER!
– TRUE

Cells stop dividing when they touch
another cell
– TRUE
Controls of Cell Growth

Mitochondria dictate when a cell will
divide
– FALSE – the nucleus (DNA, chromosomes)
dictates when a cell will divide

Cell division can speed up & slow down
under certain conditions
– TRUE - (Injury, change in genetics,
chemicals)
Cell Cycle Regulators

The protein that controls cell division
is called Dividein
– FALSE…the name of the protein is
CYCLIN

Injury can speed up the timing of the
cell cycle.
– TRUE
Uncontrolled Cell Growth

Cancer = the cell’s inability to control its
own growth
– TRUE, by definition

Tumors take up space & nutrients that
normal cells need to survive
– TRUE

It is normal for a cell to uncontrollably
divide every now and then
– FALSE – that would be CANCER
Causes of Cancer

Cancer MUST come from a change in
genetics!!!
– Radiation

Sun’s UV rays, X-rays, nuclear
– Chemicals

Nicotine, toxic waste, other chemicals
– Viruses

ONLY IF it changes your DNA
– Genetic mutations (inherited)

In the spot that regulates cell division
Treatments for Cancer



Radiation
– “zap” the uncontrolled cells. You better kill
them all. Miss one, it will start
uncontrollablly dividing again!
Surgery
– Cut out the bad cells. You better get them
all…or…
Chemotherapy
– Use chemicals to slow down all cell division
in your body. Leads to hair loss, stomach
problems, weakness, etc.