DNA repair and cancer

Question 1

Why is DNA integrity important

Answer 1

Don’t want mutations
mutation can lead to cancer
want to pass on the correct DNA to the next generation

Question 2

Exogenous DNA damage

Answer 2

Ionising radiation
alkylating agents
mutagenic chemicals
anti-cancer drugs
free radicals

Question 3

Endogenous sources of DNA damage

Answer 3

Replication error

free radicals

Question 4

Types of DNA damage

Answer 4

Apurinic site
deamination
mismatch
pyrimidine dimers
double-stranded and single-stranded DNA breaks
intercalating agents
interstand crosslink
bulky adults

Question 5

apurinic site

Answer 5

Location in DNA that has neither a purine or a pyrimidine base

Question 6

Deamination

Answer 6

C->U

Question 7

Pyrimidine dimer

Answer 7

UV likeability links adjacent T orC

Question 8

Bulky adducts

Answer 8

Ads on a bulky chemical to bases

Question 9

DNA replication stress

Answer 9

Inefficient replication that leads to replications fork slowing, stalling and/breakage

Question 10

What can cause DNA replication stress

Answer 10

Replication machinery defects
replication fork progression hindrance
defects in response pathways

Question 11

Replication for progression hindrance examples

Answer 11

Pyrimidine dimers
repetitive DNA
DNA secondary structure
fragile sites on DNA
transcription bubble ahead

Question 12

Issues with repetitive DNA

Answer 12

Can cause replication fork slippage, depending on the Strand it occurs can result in addition or loss of nucleotides

Question 13

Trinucleotide repeat disorders name one

Answer 13

Huntington’s

Question 14

Describe Huntington’s disease

Answer 14

HTT gene
CAG repeat- results in poly glutamate repeats
normal individual has 6 to 39 repeat
disease 35 221 repeats
these two neuron derogation

Question 15

DNA damage response has three different outcomes

Answer 15

Senescence
proliferation
apoptosis

Question 16

Base excision repair

Answer 16

Useful single-stranded break, U or a basic site

Question 17

Nucleotide excision repair

Answer 17

Pyrimidine dimers, moves larger region

Question 18

Mismatch repair

Answer 18

With little region

Question 19

How to repair double-stranded breaks

Answer 19

Non-homologous end joining

homologous director prepare

Question 20

Which stage of the cell cycle would use homologous recombination the most

Answer 20

Synthesis, as has a template strand to use

Question 21

Describe nonhomologous end joining

Answer 21

KU70/80 protects’s
DNA PKcs removes damaged ends
broken and ligated together

Question 22

Describe the process of homologous recombination

Answer 22

Resection- XO nucleus has cut DNA to make single-stranded DNA which is commentary sister chromatid
single strands can now invade opposite chromosome
D loop formation
Holliday junction migration
result either non-crossover product or crossover product due to the way strands are cut

Question 23

Intra tumour heterogeneity

Answer 23

Many sub clones in tumour

Question 24

Synthetically full strategies being used for BRAC1/2

Answer 24

PARP
use information on pathways and genes which are mutated to our advantage we know the cancer cells can handle double strand breaks very well therefore to our advantage