2: DNA Repair

a mutation in which the codon CGU is altered to CGA but the same amino acid is still inserted into the polypeptide chain would be which type of mutation?

silent mutation

which type of point mutation results in a different amino acid being inserted into the polypeptide chain?

missense mutation

which mutation causes premature termination of a polypeptide chain during translation?

nonsense mutation

which mutation will result in misreading of all codons downstream of the mutation?

frameshift mutation

a trinucleotide repeat expansion disease having earlier onset with subsequent generations is an example of what?

anticipation

what causes thymidine dimers?

ultraviolet radiation

what type of spontaneous DNA damage results from the cleavage of the glycosidic bond between deoxyribose and a purine base?

depurination

what type of spontaneous DNA damage is the hydrolytic conversion of a DNA-cytosine residue to uracil?

deamination

what is the term for environmental DNA damaging agents that can cause DNA damage?

mutagens

what is process by which unrepaired 06-methylguanine mispairs with thymine, leading to a G-C or A-T transition mutation?

mutagenesis

what is the DNA repair mechanism that uses visible light to repair T-T dimers?

photoreactivation

what is the enzyme that directly repairs alkylation damage by transferring the alkyl group from the O6 position of guanine to itself?

06-methylguanine DNA methyltransferase (MGMT)

what is the repair pathway that removes damaged bases by using DNA glycosylases to cleave the bond between the base and the sugar-phosphate backbone?

base excision repair (BER)

what is the repair pathway that involves endonuclease cleavage on both sides of a damaged site to remove and replace a segment of DNA?

nucleotide excision repair (NER)

what is the name of the rare genetic disease caused by a deficiency in the NER pathway, leading to extreme sensitivity to sunlight and a high incidence of skin cancers?

xeroderma pigmentosum

what is the DNA repair system that corrects errors, such as mismatched bases, introduced during DNA replication

mismatch repair

what is the most lethal form of DNA damage, which can be caused by ionizing radiation?

double-strand break (DSB)

what is the DNA repair mechanism that uses an undamaged homologous chromosome as a template to precisely repair a double-strand break?

homologous recombination

which 3 enzymes are involved in nucleotide excision repair?

endonuclease, DNA polymerase, DNA ligase

a patient has recurrent blistering of the skin that occurs within 15 minutes of going outside — a defect in which repair pathway is most likely?

nucleotide excision repair

defects in nucleotide excision repair increase the risk of what condition?

melanoma

which repair mechanism is responsible for repairing damage to DNA one by alkylation, deamination, and oxidation?

base excision repair

what is the order of enzyme activity in base excision repair? (GEL PLease)

• glycosylase

• AP endonuclease

• lyase

• DNA polymerase B

• DNA ligase

what is the name of the DNA repair mechanism for double-strand breaks that is more efficient but can result in the loss of genetic information if DNA ends are not rejoined at the precise sites of breakage?

non-homologous end joining

what is the process where damage-tolerant, error-prone DNA polymerases are used to replicate past damaged sites?

translesion synthesis

which DNA repair mechanism can occur through the entirety of the cell cycle?

base excision repair

which mutation makes breast and ovarian cancer more likely?

homologous recombination defect due to BRCA1 mutation

what are the three major protein kinases that regulate the DNA damage response?

DNA-PKcs, ATM, and ATR

which protein kinase is responsible for sensing double-strand breaks?

ataxia-telangiectasia mutated (ATM)

which protein kinase is responsible for sensing single-stranded DNA?

ATR (ATM and Rad3-related)

what is the rare autosomal recessive genetic disease is caused by a mutation in the ATM gene resulting in defective nonhomologous end joining?

ataxia-telangiectasia