Cell Cycle

Question 1

What happens during the G0 phase?

Answer 1

Resting phase

Cell has stopped dividing

Question 2

What is the G1 phase?

Answer 2

Gap 1
Cells increase in size
G1 checkpoint mechanism ensures everything ready for DNA synthesis

Question 3

What is the S phase?

Answer 3

Synthesis

Where DNA replication occurs

Question 4

What is the G2 phase?

Answer 4

Gap 2
Gap between DNA synthesis and mitosis
Cells continue to grow
G2 checkpoint mechanism ensures everything ready for M phase

Question 5

What is the M phase?

Answer 5

Mitosis
Cell growth ceases
M phase checkpoint mechanism ensures cells ready to complete division

Question 6

What 3 stages are part of interphase?

Answer 6

G1
S
G2

Question 7

What are the checkpoints?

Answer 7

System of cyclically active & inactive enzymes

Question 8

Checkpoints - catalytic sub-unit activated by?

Answer 8

Regulatory sub-unit

Question 9

What are the catalytic sub-units?

Answer 9

CDKs - cyclin- dependent kinases

Question 10

Checkpoints- what are the regulatory sub-units?

Answer 10

Cyclins

Question 11

Checkpoints -

What is the active enzyme complex?

Answer 11

CDK/ cyclin complex

Question 12

What do active CDK/ cyclin complexes do?

Answer 12

Phosphorylase target proteins

Question 13

What is a CK1?

Answer 13

A CDK inhibitor

Question 14

What is the retinoblastoma gene case?

Answer 14

Encodes pRb

PRb is hypophosphorylated
Phosphorylation increases as cells progress through cell cycle

Active cyclin / CDK complexes phosphorylase pRb

Inactive pRb loses affinity for E2F - free E2F transcription factor activates vital target genes

Question 15

What is E2F?

Answer 15

Retinoblastoma case

Hypophoshorylated/ active Rb inactivates E2F

Inactive Rb loses affinity for E2F - free E2F transcription factors activates vital target genes

Question 16

What causes carcinogenesis?

Answer 16

Mutation of genetic material that upsets the normal balance between proliferation and apoptosis

Question 17

Uncontrolled proliferation of cell leads to…

Answer 17

Tumours

Question 18

What are carcinogenic environmental agents?

Answer 18

Chemicals

Radiation

Oncogenes viruses

Question 19

What are the two regulatory pathways that are frequently disrupted and that frequently cause cancer?

Answer 19

The cyclin D-pRb-E2F pathway

P53 pathway

Question 20

Function of P53

Answer 20

Maintains genomic intergrity

Facilitates DNA repair

Question 21

P53 levels increase in

Answer 21

Damaged cells

Induces cell cycle arrest at G1

Question 22

Genetically damaged cells proliferate and form?

Answer 22

Malignant neoplasms