Lecture 10 - Instability of Human Genome

Question 1

Mutations change the base in a segment of DNA; _________ dimers distort the DNA helix.

Answer 1

Thymine

Question 2

O6-methylguanine-DNA methyltransferase removes a methyl group from guanine residues that would otherwise permit the base pairing of guanine with _______. O6-methylguanine-DNA methyltransferase does not hydrolyze __________ bonds in catalyzing the removal of the guanine methyl group.

Answer 2

Thymine

Phosphodiester

Question 3

Global Genome Repair (GGR) removes DNA damage that represents a __________ in the helix. GGR involves many proteins that are defective in xeroderma pigmentosum. Transcription coupled repair involves two proteins that are defective in Cockayne’s syndrome.

Answer 3

Distortion

Question 4

Both GGR and _______ involve a protein that also functions in transcription, termed TFIIH and several proteins that function in DNA replication, such as the clamp loader, termed RPC and the clamp, termed PCNA.

Answer 4

TCR

Question 5

In the first step of Base Excision Repair (BER), a nucleotide removes a base, without hydrolyzing any phosphodiester bonds.

Answer 5

DNA glycosylase

Question 6

____________ is closely associated with DNA replication. Several proteins involved in MMR are defective in a hereditary form of _____________ cancer.

Answer 6

MMR

Colon

Question 7

In recombination repair, a gap that forms during replication is filled by recombining a short segment of DNA, from a parental strand of DNA, with the new strand. The gap created in the parental strand is then filled by using the correct version of the newly synthesized DNA as a template. ___________, which is defective in a certain form of hereditary breast cancer, is required for recombination repair.

Answer 7

BRCA2

Question 8

When DNA repair fails, the cell can invoke ___________ pathways that result in cell death. If such checkpoint pathways fail, the cell can accumulate mutations that may eventually be tumorigenic.

Answer 8

Checkpoint