Mitosis & Cell Cycle

Question 1

Describe the steps of the cell cycle

Answer 1

G1 –> (R) S –> G2 –> M
G1 = Grow and make sure the cell is big enough.
G2 because it double checks.

Question 2

What is the main goal of the somatic cell cycle?

Answer 2

to ensure exact duplication of the genome in S phase followed by exact of division of the genome in M phase to produce identical daughter cells.

Question 3

Know how cells prevent re-replication of their genomes by keeping the assembly and activation of replication complexes in separate cell cycle phases.

Answer 3

G1: Low CDK, allow building of pre-RC
S/M: High CDK, Activate RC, prevent building pre-RC

In G1 you’re only allowed to build & never activate. In S phase, you’re only allowed to activate & never build.

Question 4

Differentiated, post-mitotic cells such as neurons are stuck at ______ in that they ____.

Answer 4

R point; continue to grow without cycling.

Question 5

Active CDKs are made by ____________ and result in cell __________ and __________.

Answer 5

growth factor hormones; replication & duplication

Question 6

What are cellular markers of cancer?

Answer 6

Highly PO4’d or low levels of Rb
Mutations in CDI (can’t inhibit CDK)
Mutation in Ink4 (CDI for CDK4), so it pushes past “R” checkpoint
Increased mitogen (this activates CDK4)

Question 7

How is the cell cycle regulated? Cascade of 3 things

Answer 7

Sensor –> Transducer –> Effector

Question 8

What is Rad17?

Answer 8

Checkpoint gene that sees DNA damage. Rad17 –> ATM/ATR –> Chk1/2 –> p53 which inhibits CDKs and can lead to apoptosis

Question 9

What is ATM?

Answer 9

kinase recruited to ds breaks

phosphorylates key activators of dna damage checkpoint (arrest, repair, apop). Includes: p53, chk2, H2AX