DNA Damage & Repair

Question 1

First protein (2 of them) that detect DNA damage from IR for both Nonhomologous and Homologous Repair?

Answer 1

ATM and MRN (Mre11-Rad50-Nbs1)

Question 2

As a second step, what does MRN do (in nonhomologous end-joining)?

Answer 2

Recruits and activates PIKKs (Phosphatidylinositol-3-kinase-related kinase family) and DNA-PK, DNA-dependent protein kinase catalytic subunit)

Question 3

What are the two main proteins involve in DNA homologous repair?

Answer 3

RAD51 (Key protein in homologous recombination as it mediates the invasion of the homologous strand of the sister chromatid, leading to formation of Holliday junction)

RPA (forms a nucleoprotein filament)

Question 4

What protein is used to measure double strand breakage?

Answer 4

gamma-H2AX

Question 5

What type of repair is APE1 (apurinic endonuclease 1) involved in?

Answer 5

Base Excision Repair

Question 6

In which cell cycle does chromosome aberration take place?

Answer 6

G0-1

Question 7

In which cell cycle does chromatid aberration take place?

Answer 7

S/G2

Question 8

What are the two types of chromosomal changes that are NOT lethal?

Answer 8

symmetric translocation and small deletions

Question 9

What are the three types of chromosomal changes (aberrations) that are lethal?

Answer 9

Dicentric, Ring, Anaphase bridge

Question 10

What is the lowest radiation dose that you can see chromosomal aberrations in peripheral lymphocytes?

Answer 10

0.25 Gy