Cell Cycle Control

Question 1

What are the different phases of Mitosis (PPMATC)?

Answer 1

Prophase, Pro-metaphase, Metaphase, Anaphase, Telophase, Cytokinesis

Question 2

What does the ‘Interphase’ consist of?

Answer 2

G1 (Gap 1), S (synthesis), G2 (Gap 2)

Question 3

What does the ‘Mitosis’ phase consist of?

Answer 3

Mitosis and Cytokinesis

Question 4

What are the different checkpoints in the Cell Cycle?

Answer 4

Replication of DNA (S phase), Chromosome segregation (M phase), Continue proliferation (progression from G1 to S), DNA damage (progression from G1 to S).

Question 5

What is responsible for the ‘Continue proliferation’ checkpoint (G1 to S phase)?

Answer 5

It is controlled by Cyclin D, CDK 4 and 6, and Retinoblastoma.

Question 6

What is responsible for the ‘Replication of DNA’ checkpoint (S phase)?

Answer 6

It is controlled by Cyclin A and CDK2.

Question 7

What is responsible for the ‘Chromosome segregation’ checkpoint (M phase)?

Answer 7

It is controlled by Cyclin B and CDK1. Also, the Anaphase Promoting Complex (APC).

Question 8

What is responsible for the ‘DNA damage’ checkpoint (G1 to S)?

Answer 8

p53 (and CDK inhibitor 21)

Question 9

What has to happen to a Cyclin for it to be activated?

Answer 9

It needs to be phosphorylated, and have a CDK attached to it. For example, Cyclin B and CDK1.

Question 10

What does APC stand for?

Answer 10

Anaphase Promoting Complex

Question 11

What is the Anaphase Promoting Complex responsible for?

Answer 11

It is a ubiquitin ligase that catalyses the degradation of securin, allowing separase to separate the cohesin complex that keeps the sister chromatids together.

Question 12

What occurs in the G1 phase?

Answer 12

The cells grows and doubles the number of organelles inside. Precursors to DNA replication are accumulated. The chromosomes in the nucleus are decondensed.

Question 13

What occurs in the S phase?

Answer 13

DNA is replicated, each chromosome is replicated. Each copied chromosome is called a chromatid. The two copies are called sister chromatids. They remain attached until the end of mitosis.

Question 14

What occurs in the G2 phase?

Answer 14

A further growth phase occurs. The cell increases in size once again. The cell synthesizes proteins that assist in cell division, like tubulin. The centrosome is duplicated and both copies remain together.