cell cycle 3rd oct

Question 1

What are the 5 stages of cell cycle?

Answer 1

1. G0 phase
2. Gap 1
3. (S)ynthesis phase
4. Gap 2
5. Mitosis

Question 2

What happens during the G1 phase?

Answer 2

Growth of cell
cellular contents are duplicated
preparation for DNA synthesis

Question 3

What happens during S phase?

Answer 3

DNA replication of each of the 23 pairs

Question 4

What happens during G2 phase?

Answer 4

Preparation for Mitosis
More cell growth

Question 5

What are the 5 phases of mitosis?

Answer 5

Prophase
Metaphase
Anaphase
Telophase

Question 6

What happens during prophase?

Answer 6

DNA material (chromatin) condensed into chromosomes
Cell growth
Mitotic spindle fibres begin to form

Question 7

What happens during proMETAphase?

Answer 7

Nuclear envelope dissolves allowing for spindle fibres to attach

Question 8

What happens during metaphase?

Answer 8

Chromosomes line up along the metaphase plate
Spindle fibres attach at their centromere

Question 9

What happens during Anaphase?

Answer 9

Spindle fibres contract
Sister chromatids dragged apart toward the polar ends
Cell begins to elongate for cellular division

Question 10

What happens during Telophase?

Answer 10

cell dimples
nuclear envelope begins to reform
Spindle fibres break down

Question 11

What happens during Cytokinesis?

Answer 11

Cytoplasm divides- actin ring pinches cytoplasm along the crease of the two new cells- cleavage furrow.

two new cell forms

Question 12

Why isn’t cytokinesis considered its own phase?

Answer 12

Stage begins between anaphase and telophase but doesn’t finish until telophase is over.

Question 13

What are the 3 major checkpoints of cell cycle?

Answer 13

G1/S phase checkpoint
G2/Mitosis checkpoint
Spindle checkpoint

Question 14

What does the G1/S phase checkpoint do?

Answer 14

this checkpoint makes sure that the cell is committed to cell proliferation.

Question 15

what does the G2/M checkpoint do?

Answer 15

Has the dna synthesis been completed correctly?
Commitment to mitosis

Question 16

What does the spindle checkpoint do?

Answer 16

are all chromosomes attached to spindles
Can sister chromatids separate correctly

Question 17

What is DNA DAMAGE RESPONSE?

Answer 17

it detects DNA lesions, signals their presence and promotes their repair.

Question 18

What is meant by replication stress?

Answer 18

this is the trancient slowing or stalling of replication forl

Question 19

What is progression through the cell cycle primarily controlled by?

Answer 19

Proteins in the cytoplasm- Cyclins and Cyclin dependant kinases.

Question 20

when cyclins are bound to Cyclin dependant Kinases what happens?

Answer 20

cell cycle is driven forward.

Question 21

What is chromosome segregation?

Answer 21

process by which 2 sister chromatids are separated from each other.

Question 22

how do cyclins and cdk’s advance cell cycle

Answer 22

1. CDKs bind to cyclins
2. Cyclin/CDK complex is phosphorylated by a kinase (phosphate donating protein)
3. The activated Cyclin/CDK complex acts as a kinase and phosphorylates the target protein.
4. the activated protein advances the cell cycle

Question 23

What are the major types of DNA damage and their repair pathways?

Answer 23

Single strand breaks—Base Excision Repair

Double strand breaks— Homologous Recombination Repair & Non- Homologous End Joining

Nucleotide mutations/substitutions/ deletions/insertions— MisMatch Repair

Bulky Adducts (parts of the DNA chain that bind to cancer-causing chemicals)— Nucleotide Excision Repair.

Question 24

What happens when a cell senses DNA damage?