mini exam 2

Which mechanism can be used to repair UV damage in Drosophila but not in humans?

photoreactive repair

Which of the following statements is true of non-homologous end joining (NHEJ)?

it is both error-prone and a double-strand repair pathway

Which type of double-stranded break repair would you expect to be used by a cell in the

G₁ phase of the cell cycle?

non-homologous end joining

Transposons can integrate into the promoters of genes, what is the most likely outcome of such an event?

altered gene expression

In eukaryotes, homologous recombination is initiated by ________.

Spo11 generating double-stranded DNA breaks

If one Holliday junction region is resolved by an NS cut and the other by an EW cut, the resulting chromosomes

are recombinant and carry the combinations A₁ and B₂ or A₂ and B₁.

Which enzyme is required to mobilize transposons of any type?

transposase

The 'activator' transposable element Ac encodes the enzyme ________ that can cause mobilization of the 'dissociation' element Ds.

transposase

Retrotransposons are unique among transposable elements in that they require the enzyme __________ for mobilization.

reverse transcriptase

Which of the following events could result in a frameshift mutation?

Base deletion

The purpose of the Ames Test is to _______.

test the mutagenic effects of chemicals

Why are liver extracts used in the Ames test?

Liver enzymes may activate some innocuous compounds, making them mutagenic.

Which enzyme is responsible for proofreading during replication?

DNA polymerase

Which repair system uses the RecA and LexA proteins?

SOS repair

Which structures can be involved in recombination?

Chromatids of homologous chromosomes

Which process does not occur during recombination?

DNA polymerization

For which codon(s) could a single base change account for this amino acid change?

Lysine to Asparagine

AAG and AAA

For which codon(s) could a single base change account for this amino acid change?

Alanine to Phenylalanine

none

For which codon(s) could a single base change account for this amino acid change?

Leucine to Glutamine

CUG and CUA

Which repair process in E. coli uses visible light to repair thymine dimers?

photoreactivation repair

synonymous mutation

converts one codon into a different codon that codes for the same amino acid

missense mutation

converts one codon into a different codon that codes for a different amino acid

nonsense mutation

converts a codon into a different codon that codes for a stop codon

Base-pair substitution mutations:

the replacement of one nucleotide base pair by another

Transition mutations:

one purine replaces another, or one pyrimidine replaces another

Transversion mutations:

a pyrimidine is replaced by a purine or vice versa

Depurination:

the loss of a purine from a nucleotide by breaking the covalent bond linking the nucleotide base to the sugar

Deamination:

the loss of an amino group (N H2) from a nucleotide base