Genomic Instability Quiz Flashcards
Which of the following statements about genetic instability are true?
A) it is a characteristic of cancer cells
B) it can result in tumour initiation
C) it can be involved in progression
A, B, and C are all true
Which of the following about reactive oxidative species is false?
A) they result in damage to DNA which is predominately repaired by nucleotide excision repair
B) they are induced by exogenous agents
C) they are highly reactive
D) they are induced by endogenous processes
A is false
Much of damage that ROSs induce is small base adducts and strand breaks which are repaired by base excision repair and strand break repair pathways
Which of the following statements is false? An apurinic/apyrimidinic site…:
A) is an intermediate in the base excision repair pathway
B) results in a double strand break
C) is caused by the loss of a base
D) is also called an abasic site
B is false
An apurinic/apyrimidinic site generally results in a single strand break following strand nicking by AP endonuclease
Which of the following statements regarding 8-oxoG is false?
A) causes a large change in DNA structure
B) may cause a mismatch if unrepaired
C) is repaired by base excision repair pathway
D) is cleaved by OGG1
A is false
8-oxoG is a small adduct and does not affect the DNA structure
DNA damage may…:
A) result in cancer
B) result in cell death
C) result in mutations
A, B, and C are all correct
If DNA damage is unrepaired, errors may be generated in DNA replication resulting in mutated proteins.
Accumulated unrepaired mutations may result in cancer
Cell may activate apoptotic or senescent pathways if DNA damage is too great.
Which of the following is false: The cellular response to DNA damage…
A) is instigated by p53 which then activates ATM
B) can result in cell death
C) can result in cell cycle arrest
D) involves many rapid phosphorylation events
A is false
ATM and ATR are activated by DNA damage and signal to many molecules including p53
O6methylguanine is a small addicted base damage and is usually repaired by…
A) nucleotide excision repair
B) non-homologous end joining
C) mismatch repair
D) direct reversal repair
D is correct
Usually repaired by direct reversal repair but ca also be repaired by base excision repair pathway if needed
Which of the following DNA pair pathways are the MutS and MutL heterodimers involved in?
A) nucleotide excision repair
B) mismatch repair
C) direct reversal repair
D) non-homologous end joining
B is correct
MutS heterodimer binds to mismatch or insertion/deletion loop and recruits MutL
Match the following:
DNA glycosylase, Endonuclease, DNA ligase, DNA polymerase
Cleaves DNA chain, Adds nucleotides, Joins two strand ends, Removes damaged base
DNA glycosylase: Removes damaged base
Endonuclease: Cleaves DNA chain
DNA ligase: Joins two strand ends
DNA polymerase: Adds nucleotides
Which of the following statements about double strand break repair is true?
A) both HR and NHEJ occur throughout cell cycle
B) Ku70/80 act in HR pathway to recognise and bind to broken DNA ends
C) Replication protein A coats single stranded DNA formed during HR pathway
D) RAD51 is major protein involved in NHEJ pathway
C is true
NHEJ only takes place after chromatids have replicated (S and G2)
Ku70/80 act in NHEJ not HR
RAD51 involved in HR not NHEJ
What is translocation?
A) loss of a large portion of a chromosome
B) gain of a single nucleotide
C) variation in short repeats found within genome
D) rearrangement of non-homologous chromosomes
D is correct
Microsatellite instability = variation in short repeats within genome
Additions = gain of genetic material
Deletions = loss of genetic material
Which of the following is true? Acquisition of mutations may result in…
A) clonal heterogeneity
B) genetic instability
C) initiation of a cancer when they occur in TSGs or oncogenes
A, B, and C are all true
Different mutations selected to produce different sub clones in tumour -> heterogeneity
Further genetic instability f they occur in DNA damage response genes.
Mutations often activate oncogenes / inactive TSGs, common in cancer initiation
Match following syndromes with gene/pathway they are defective in:
Xeroderma pigmentosum, Hereditary nonpolyposis colorectal cancer, Cockayne’s, Bloom, Li fraumeni
Mismatch repair, p53, Nucleotide excision repair, Double strand break
Xeroderma pigmentosum => NER Hereditary nonpolyposis colorectal => Mismatch Cockayne’s => NER Bloom => Double strand break Li fraumeni => p53
Which of the following are associated with causing cancer via DNA damage?
A) smoking
B) sunbathing
C) some bacterial infections
D) some viral infections
A, B, C, and D are all correct
