Cell cycle

Question 1

What are the 2 phases of the cell cycle?

Answer 1

mitotic (M) phase
Interphase (cell growth/ copying of chromosomes in preparation for cell division)

Question 2

2 steps of the mitotic phase?

Answer 2

mitosis and cytokinesis

Question 3

Which phase is 90% of the cell cycle?

Answer 3

interphase

Question 4

What are the steps of interphase?

Answer 4

G1 phase: first gap
S phase: synthesis
G2 phase: second gap
G0 phase: resting phase, postmitotic quiescent

Question 5

Which step doubles the amount of organelles, is precommitment, lasts 6-24 hours, and requires nutrients and growth factors?

Answer 5

G1

Question 6

Which phase includes DNA replication, doubles the amount of DNA, lasts 7-8 hours, first commitments stage, GF not needed, outcome is 2 identical daughter cells?

Answer 6

S phase

Question 7

Which phase is the interval between DNA synthesis and mitosis, enzyme/protein and ATP synthesis occurs here, and lasts 3 hours?

Answer 7

G2

Question 8

In which stage does the cell undergo mitosis and then cytokinesis and lasts 1-2 hours?

Answer 8

M phase

Question 9

Steps of cell division?

Answer 9

Prophase  prometaphase  metaphase  anaphase  telophase  CYTOKINESIS!

Question 10

In which stage is a state of withdrawal, not dividing or preparing to divide, just goin’ about day-to-day cell business, common in differentiated cells? Hepatocytes and neurons are examples?

Answer 10

G0

Question 11

What are checkpoints based on?

Answer 11

A series of biochemical switches

Question 12

True or false. Checkpoints can be regulated by BOTH factors within the cell, mostly controlled by the “health” or “state of preparation” of the cell and factors from outside the cell – i.e. messages from other cells within the same tissue or distant cells

Answer 12

true

Question 13

Which is the rate limiting and committing step of the cycle, for transitions?

Answer 13

G1/S. DIE OR DIVIDE

Question 14

Which type of kinases are key to the cell cycle control system? What do they do?

Answer 14

cyclin-dependent kinases (Cdks)

PHOSPHORYLATE (therefore initiate/regulate)

Question 15

Cyclical changes in cyclin protein levels result in the cyclic assembly and activation of what?

Answer 15

cyclin-cdk complexes at specific stages of the cell cycle

Question 16

What are the 4 classes of cyclins that form specific complexes with Cdks?

Answer 16

1. G1 cyclins=cyclin D +cdk4/6 = Needed for progression through the start transition
2. G1/S cyclins = cyclin E +cdk2 = Trigger progression through Start Transition
3. S-cyclins = cyclin A + cdk1 and cdk2 = Stimulate chromosome duplication
   Involved in early mitotic events
4. M-cyclins: cyclin B + cdk 1 = Stimulate progression through G2/M checkpoint

Question 17

Can a cyclin-CdK complex can induce different effects at different times in the cell cycle? Or is it always the same effect?

Answer 17

Different, because accessibility changes

Question 18

What is the regulatory checkpoint within mitosis? What kind of regulation? What complex is needed? How is it used?

Answer 18

metaphase to anaphase

regulated proteolysis

APC/C = anaphase promoting complex aka cyclosome

Stimulate proteolytic destruction of specific regulatory proteins

APC/C polyubiquitinates specific target proteins for destruction in proteasomes.

Target proteins: securin, M-cyclins, S-cyclins