Radiosensitivity and Cell Cycle

Question 1

What is the order for cell cycle?

Answer 1

G1 –> S –> G2 –> M

Question 2

G2 checkpoint is done by which protein?

Answer 2

p34(Cdc2) kinase

Question 3

p53 mediates which cycle of checkpoint?

Answer 3

G1 checkpoint

Question 4

What is the order of the cell cyclin B, D1, E, A?

Answer 4

Question 5

What assay do you use for cell cycle?

Answer 5

radioactive tritium (3H-TdR)

Question 6

What cell cycle is between M and S?

Answer 6

Gap 1 or G1

Question 7

What is the order of cell cycle that are sensititve to radiation

Answer 7

(most sensitive) M –> G2 –> G1 –> S (least sensitive)

Question 8

Definition of Oxygen Enhancement Ratio (OER)?

Answer 8

The ratio of doses administered under hypoxic to aerated conditions needed to achieve the same biologic effect

Question 9

Which cell cycle has a higher OER (oxygen enhancement ratio)?

G2 phase or S phase?

Answer 9

S phase (since it takes more oxygen to lead to the same killing effect during S phase compared to G2 phase)

OER of G2 is 2.3 - 2.4

OER of S phase is 2.8 - 2.9