Molecular Genetics Ch. 19 - Learnsmart

Steps of homologous repair

DSB is processed at break site strand exchange DNA synthesis resolution and ligation

Eukaryotic homologs for which of the following have been found so far?

MutS and MutL

MutL

acts as a linker that helps loop the DNA

In a neutral mutation, a negatively charged amino acid is substituted for _____________.

another negatively charged amino acid

A mutant Drosophilia fly can land on the side of a fly bottle when the bottle in incubated at 20 - 23 degrees but not at 24 - 27 degrees. This is an example of a(n) ____________ mutation.

conditional

MutS

detects the mismatch

Exonuclease

digests the nonmethylated strand

The addition or deletion of a number of bases that is not a multiple of 3 causes a(n) ___________ mutation.

frameshift

What can cause double-strand breaks (DSBs)?

gamma rays reactive oxygen species x-rays

Defects in the human mismatch repair genes, hMSH2 and hMLH1, play a role in the development of ________.

hereditary nonpolyposis colorectal cancer

Double-strand breaks are typically repaired by which of the following?

homologous recombination repair nonhomologous end joining

The restoration of protein function by a second mutation in a different gene is known as a(n) _______________.

intergenic suppressor

The restoration of function by a second mutation at a different site in the same gene is known as ____________.

intragenic suppressor

Error-prone replication is a characteristic of __________.

lesion-replicating polymerases

MutH

makes a cut in a nonmethylated strand

An individual that has one copy of the sickle cell allele and one copy of the wild-type allele has an increased level of resistance to the disease __________.

malaria

An allele that has a DNA sequence different from that of the wild-type is called a(n) __________ allele.

mutant

A heritable change in genetic material is called ______.

mutation

A mutation that results in a premature termination of the synthesis of a polypeptide is called a(n) ______________ mutation.

nonsense

Which mutation changes a mutant allele back to a wild-type allele?

reversion

MutU

separates strands at the cleavage site

A main advantage of nonhomologous end joining is that it does not require an _________ _________, and this it can take place throughout the cell cycle.

sister ; chromatid

A second mutation that occurs in a different site than the first mutation, and which converts the mutant back to the wild-type phenotype, is best referred to as a(n) ___________ mutation.

suppressor

The strand that is repaired in the mismatched repair system is _____________.

the nonmethylated strand

The wild type genotype or phenotype is the one that is _________ found in nature.

typically

Mutations that occur in a promoter sequence can be divided into two types: _________ promoter mutations increase the transcription rate, while _____________ promoter mutations decrease it.

up ; down

A breakpoint refers to the region ____________.

where two chromosomes pieces break and rejoin with other chromosome pieces within a gene