Chapter 11.2.1 (Exam 2) Cell Cycle

Question 1

What is the cell cycle?

Answer 1

Phases a cell passes through to produce daughter cells by cell division

Question 2

Describe interphase in the cell cycle.

Answer 2

Nucleus is visible and cell functions occur

Duration of interphase is highly variable

Interphase has 3 subphases

Question 3

What are the three subphases of interphase?

Answer 3

G1, S, and G2

Question 4

Describe the G1 phase.

Answer 4

Chromosomes are single (unreplicated)

Duration is variable, from minutes to years, and some cells enter a resting phase (G0)

Ends at the G1-to-S transition, when commitment is made to DNA replication and cell division

Question 5

Describe the S phase.

Answer 5

DNA replicates; sister chromatids remain together until mitosis

Question 6

Describe the G2 phase.

Answer 6

Cell prepares for mitosis, e.g., by synthesizing the structures that move the chromatids

Question 7

What does the M phase include?

Answer 7

Mitosis and cytokinesis

Question 8

How is progress through the cell cycle controlled?

Answer 8

Cyclin-dependent kinases (CDKs)

Question 9

How are CDKs activated?

Answer 9

CDKs are allosterically activated by cyclin, which changes its shape to expose its active site

Question 10

What is one example of a point in the cell cycle controlled by a CDK?

Answer 10

A particular CDK controls the G1-to-S transition, a control point in the cell cycle called the restriction point (R)

Question 11

What does progress past the restriction point depend on?

Answer 11

Progress past the restriction point depends on retinoblastoma protein (RB)

Question 12

What is the normal function of retinoblastoma (RB) compared the the function of phosphorylated RB?

Answer 12

RB’s normal function is to inhibit the cell cycle

RB is phosphorylated by CDKs, becomes inactive and no longer blocks the cell cycle