Lecture 6 Flashcards Preview

BMS242 - Cell and Molecular > Lecture 6 > Flashcards

Flashcards in Lecture 6 Deck (13)
Loading flashcards...
1

what are the 4 ways DNA can be damaged

thermal degredation
metabolic degredation
environmental substances
radiation

2

what is cytosine deamination

what C becomes U do to attack by water

3

what is a transition mutation

purine to purine
more likely
less likely to cause AA sub

4

transversion

purine to pyrimidine
less likely
dangerous

5

what is a frameshift mutation

lose base pair on one strand
creates missense protein

6

what causes pyrimidine dimers

UV light

7

how would you resolve depurination

base excision repair
endonuclease and phosphodiesterase removes backbone
DNA polymerase adds base pair

8

how would you resolve pyrimidine dimers

nucleotide BER
cutes 12 ssDNA around dimer
DNA helicase pulls it off

9

how would you bypass DNA damage

translesional DNA polymerase

10

what are the two mechanisms for solving double end breaks

non-homologous end joining
homologous recombination

11

describe NHEJ

ends of DNA stuck back together
usual loss of sequence = frameshift mutation
could join any strand as there is no template

12

describe HR

nuclease digests 5' ends of broken strand
strand invasion from homolog template strand
repair polymerase synthesis uses undamaged DNA as template
invading strand released
DNA synthesis continues
highly accurate

13

what disease arised from failure in DNA repair systems

Xeroderma Pigmentosum
profound UV sensitivity