Cell cycle and checkpoints in Cell Division

Question 1

In which phase does preparation for one cell to become two happen?

Answer 1

G1 phase (Protein synthesis/Start of Cycle)

Question 2

What phase is it where the cell begins replicating its non-chromosomal content?

Answer 2

G1 phase(Protein synthesis/start of cycle)

Question 3

What phase is it where each of the 46 chromosomes is duplicated by the cell?

Answer 3

S phase(DNA synthesis)

Question 4

Phase where the cell double-checks duplicated chromosomes for errors, making any needed repairs. What phase?

Answer 4

G2(proof-reading/repair)

Question 5

Phase where the duplicated chromosomal DNA condenses into mitotic chromosomes. The chromosomes are distributed to opposite parts of the cell that will pinch off to become two new daughter cells. What phase?

Answer 5

M phase (cell division)

Question 6

What happens at G0 phase?

Answer 6

Cell is QUIESCENT-the cell is metabolizing nutrients & performing its functions.

Question 7

Is there cell division preparation at G0?

Answer 7

NOPE!

Question 8

Are CDKs dependent on Cyclins?

Answer 8

Yes

Question 9

What do cyclins do to CDKs?

Answer 9

Cyclin subunits determine which proteins are phosphorylated by the CDK

Question 10

Cyclin Dependents Kinase must be bound to ___ to activate CDK activity

Answer 10

CDK

Question 11

_____Phosphorylates serine/threonine residues of proteins that
need to be activated or inactivated during a specific phase
of the cell cycle.

Answer 11

CDK

Question 12

_____levels remain constant throughout the cell cycle

(activity is primarily controlled by levels of _____

Answer 12

CDK

cyclins

Question 13

What part of the cyclin-CKD complex can be Made and degraded as needed during each phase of the cell cycle?

Answer 13

Cyclin

Question 14

What is a mitogen?

Answer 14

(growth factor) is an extracellular ligand that initiates a signaling response which ultimately results in cell division.

Question 15

Provide steps of cell cycle (5)

Answer 15

1. Mitogen binds to receptor (on cell surface)
2. Phosphrylation cascade throug Ras
3. MAP kinase increases synthesis & activity of transcription factor MYC.
4. MYC increases the expression of the G1
   - associated cyclin, cyclin D.
5. Cyclin D-CDK4/6 first active cyclin-CDK complex of the cell cycle

Question 16

What happens if there is no mitogen signal?

Answer 16

cyclin D levels remain too low to stimulate CDK 4/6 activity which makes cell enter the QUIESCENT state G0

Question 17

Which cyclin is the only one that is dependent upon an external signal (mitogen)?

Answer 17

Cyclin D

Question 18

_____ protein allows the activation of the E2F transcription factor

Answer 18

Rb

Question 19

Transcription factor. It increases the expression of the G1-associated cyclin, cyclin D

Answer 19

MYC

Question 20

Involved in the PHOSPHORYLATION CASCADE when a MITOGEN binds to their receptors on the surface of a cell.

Answer 20

Ras

Question 21

This cyclin is associated with G1 and is the first active cyclin-CDK complex of the cell cycle

Answer 21

cyclin D

Question 22

It is a complex with cyclin D to begin G1 phase

Answer 22

CDK4/6

Question 23

Which cyclin forms a complex with CDK2, which allows the cell to pass through the RESTRICTION POINT?

Answer 23

cyclin E

Question 24

The phosphorylation state of ____ determines whether E2F can actiate transcription of S-phase genes.

Answer 24

Rb

Question 25

Which transcription factor is needed for the transcription of S phase genes, which are required for DNA synthesis?

Answer 25

E2F

Question 26

Which protein is under INK4, which ONLY inhibits CDK4 or CDK6?

Answer 26

p16

Question 27

When is p16 induced?

Answer 27

during times of environmental stress (starvation, illness)

Question 28

Which is the ONLY phase that p16 can halt the cell cycle?

Answer 28

G1 phase

Question 29

Which protein inhibits all cyclin-CDK’s EXCEPT CDK4 and CDK6?

Answer 29

p21 protein

Question 30

This protein is induced following DNA damage and can halt the cell cycle in ANY phase

Answer 30

p21

Question 31

Production of p21 is regulated by which other protein?

Answer 31

p53

Question 32

Inhibition of cyclin E-CDK2 by protein ____ can block the cell cycle at the restriction point in late G1 by preventing hyperphosphorylation of Rb.

Answer 32

p21