Cell Proliferation

Question 1

3 types of signal proteins

Answer 1

mitogens: stimulate cell division
growth factors: stimulate cell growth
survival factors: suppress apoptosis

Question 2

phases of the cell cycle

Answer 2

G1: prepares cell for DNA replication (enough nutrients, growth factors, DNA damage)- then G0
S: synthesis (DNA replication to make 2 copies of chromosomes)
G2: organelle synthesis
M: mitosis (chromosome segregation and cytokinesis)

Question 3

what are the four checkpoints within the cell cycle

Answer 3

G1 checkpoint
G1/S checkpoint
G2 checkpoint
M checkpoint

Question 4

What is the role of pRB

Answer 4

Regulates the G1 checkpoint
If there are no GF, pRB binds to transcription regulators, preventing the continuation of the cell cycle.
GF phosphorylate the pRB, removing them from the promotor region so the trsansription factor can bind

Question 5

What is the role of p53 and p21

Answer 5

p53: checks for DNA damage. Increased p53 leads to transcription of p21.
p21 inhibits cdk- preventing continuation into S phase so there is more time for repair.
If damage is too great then p53 causes cell apoptosis.

Question 6

what are the different cyclin-cdk complexes

Answer 6

G1: cyclinD + cdk4, cyclinE + cdk2

S: cyclinA + cdk2

G2: M-cdk initiates mitosis