Cancer and altered genome

Question 1

Transition mutation

Answer 1

Amino acid stays the same

Question 2

Transversion mutation

Answer 2

Amino acid changes

Question 3

Which gene mutates in response to UV light for survival?

Answer 3

UmuDC

Question 4

How often are bases chemically altered/interchanged

Answer 4

Rarely

Question 5

Describe how misrepair of bases causes mutations

Answer 5

Damaged base can not pair and code

Pairing base is inserted by guesswork

Damaged base is replaced with complementary base

Question 6

Give an example of a misrepair mutation

Answer 6

Oxidised guanine pairs with adenine then gets changed to thymine

Question 7

Any point methylated except _ causes mutation.

Answer 7

5

Question 8

What is the most common nucleotide pair that is damaged?

Answer 8

T-T

Question 9

What is the hardest nucleotide pair to repair?

Answer 9

C-C

Question 10

Which enzyme recognises damage to the pyrimidine dimer and repairs the nucleotides?

Answer 10

XPC recruits XPF and XPG to either side to excise and replace sequence

Question 11

What repairs DNA breaks?

Answer 11

cu70/80 and ligase

Question 12

What is a dirty DNA break and how can it cause mutation?

Answer 12

Nucleotides at the end of the break can be lost

Loss or addition of nucleotides can cause frameshift, insertion or deletion

Question 13

_____ can get rid of nucleotides until the sequences are complementary and can pair.

Answer 13

Ctip

Question 14

When does homologous recombination occur?

Answer 14

late s phase and g2

Question 15

What proofreads bases during replication?

Answer 15

3-5 exonuclease function

Question 16

What detects mismatches after transcription is complete?

Answer 16

MSH

Question 17

What is the problem with MSH?

Answer 17

Doesn’t know which strand is wrong

Question 18

How is mismatch repaired?

Answer 18

EX01 chews out from gap to mismatch and polymerase corrects

Question 19

What do signature mutations show?

Answer 19

Which DNA repair pathway is lacking

Question 20

What is non homologous end joining?

Answer 20

DNA Ligase joins 2 ends of a clean break together

Question 21

What is homologous recombination?

Answer 21

Using the other chromosome to repair the damaged one

Question 22

Describe homologous recombination

Answer 22

CtIP/MRN complex then Exo1

Single strand DNA stabilised by SSB

RAD51 replaces SSB

Homology search and strand invasion

Branch migration

Transcription

Ligation