Lec 8-1

Question 1

Radiation

Answer 1

High energy radiation removes electrons from atoms, altering chemical structure of bases and inducing double stranded DNA breaks

Stalls/Stops DNA replication

Question 2

UV radiation

Answer 2

Causes pyrimidine dimer formation (Usually TT, but TC/CC are possible)

Stalls/Stops DNA replication

Question 3

SOS system in bacteria, translesion system

Answer 3

Bypasses pyrimidine dimers during DNA replication, but at a high error rate

Question 4

Radiation exposure in humans

Hiroshima

Answer 4

Initial survivors got radiation sickness

Somatic mutations that lead to cancer

Question 5

Mutagen

Answer 5

Any environmental agent that increases mutation rate

Question 6

Base analogs

Answer 6

Chemical structure resembles base

ex. 5-bromouracil resembles thymine, except it has a bromine atom in place of the methyl group

Question 7

Intercalating agents

Answer 7

Insert between adjacent bases

Distort 3D structure of helix

ex. Ethidium Bromide

Causes insertions and deletions

Results in frameshift mutations

Question 8

Forward genetic screens

Answer 8

Identify genes that contribute to a phenotype/trait

After conducting a genetic screen, we have a collection of new mutants

Question 9

Forward genetics problem

Answer 9

We do not know if some of the same genes have been hit multiple times

Question 10

Forward genetics solution

Answer 10

Complementation tests are used to identify where mutants are