GENETICS 2072 EXAM 2 CH 7,8,9

true

T or F: if a geneticist relied on spontaneous mutation rates she would likely have to screen through millions of animals to find a mutant in any one particular gene

1. glycosylase recognizes an abnormal base and cleaves the bond between the base and the sugar 2. AP endonuclease recognizes the missing base and cleaves the DNA backbone 3. DNA polymerase removes the damaged DNA and replaces it 4. DNA ligase seals the nick in the DNA backbone

steps in the base excision repair system

1. parental strands are marked with methyl groups 2. MutS and MutL recognize mismatch in replicated DNA 3. MutL recruits MutH, which makes a nick opposite the methyl tag 4. DNA exonucleases remove DNA from the new strand 5. the new strand is repaired and methylated

the order of steps of the methyl-directed mismatch repair system

trinucleotide repeat

the phenomenon in which a repeated sequence of three bases increases in number generation after generation is called ____ expansion

enzyme

the results of Beadle and Tatum's experiments with Neurospora auxotrophs were summarized as the "one gene, one ____" hypothesis

the nonmethylated strand

the strand that is repaired in the mismatch repair system is ____

homologous; nonhomologous

the two main mechanisms used to repair DNA double-strand breaks are ____ recombination repair and ____ end-joining.

deletion

to be able to efficiently map a thousand mutations, Benzer took advantage of a technique that first localized each mutation to a region, known as ____ mapping

thymine dimers

ultraviolet light causes the formation of cross linked ____ in DNA

mutations may occur at multiple stages of development before gametes form

what best explains why multicellular organisms have a higher mutation rate than bacteria?

they arise from a heritable mutation that creates a damaged enzyme for a specific biochemical reaction

what best summarizes Garrod's hypothesis about alkaptonuria and other "inborn errors of metabolism"?

proteins that provide cell shape, receptor proteins, proteins that support chromosomes, enzymes, and protein hormones

what is encoded by genes?

transition

A to G is a base change for what type of mutation ?

transversion

A to T, A to C, and G to C are examples of what mutation?

hotspot

a region of a gene that is especially prone to mutation is call a(n) ____

transition mutation

a tautomeric shift can produce a ____

abnormal bases

base excision repair is the main system used in the repair of ____

they respond to a wide range of wavelengths, they make up the majority of light-receiving cells, and they oversaturate in bright light

characteristics of rods

Huntington; fragile X

examples of trinucleotide repeat expansion disorders include ____ disease, from the HD gene, and ____ syndrome, from the FMR-1 gene

plaques

on a plate of E. coli, the round clear areas that are sites of phage infection events are known as ____

A, G

purines

C, T

pyrimidines

a functional unit that directs the appearance of a molecular product, in turn, contributes to a particular phenotype

the best definition of a gene

double-strand

the breakage of chromosomes is referred to as a(n) ____ break

photolyase; alkyltransferase

the enzyme that can recognize thymine dimers and split them is called ____. the enzyme that can remove methyl and ethyl groups from guanine is called ____

primary

the linear sequence of amino acids is known as the protein's ____ structure

germ-line

the only novel mutations that can be passed down to progeny are those that arise in the a ____

depurination

the removal of a purine from DNA is called _____

transversion

a base substitution in which a purine and a pyrimidine are interchanged is called a(n) ____ mutation

substitution

a change of one base for another is described as a base ____ mutation

significantly higher than that of the control plate

a chemical agent is being assayed for mutagenicity using the Ames test. this agent would be judged to be a mutagen of the number of bacterial colonies on the test plate is ____

N; C

in a polypeptide, the end with an amino group is known as the ____ terminus, and the end with the carboxyl group is known as the ____ terminus

tautomeric shift

a temporary change in DNA base structure due to movement of hydrogen atoms is called a(n) ____

1. transition 2. insertion of 1 base pair 3. deletion of 5 base pairs

rank mutations from most likely to undergo reversion to least likely

the white mutations are in one gene, the orange mutations in another; the five mutations are in five different genes; all mutations are in the same gene

a genetic screen for eye color mutations produced three flies with white eyes and two with orange eyes. next the location of the mutations will be sequenced. what results are possible?

substitutes a single amino acid

a missense mutation is one that ____

complement

if two chromosomes carry mutations in SEPARATE genes, the remaining wild-type alleles will ____ each other to provide normal function

mutations were a response to the phage

imagine if when Luria and Delbruck did the fluctuation experiment, every culture had produced between 5-7 resistant colonies. they would have concluded that ____

forward mutation

a mutation that changes a wild-type allele of a gene to a different allele is called a ____

germ-line

a mutation that occurs directly in a sperm or egg cell, or in one of their precursor cells, is referred to as a(n) ____ mutation

analogs

certain compounds have a structure similar to normal DNA bases and so can be incorporated into daughter strands during DNA replication. these compounds are called base ____

recombination frequency

in Benzer's fine structure mapping experiment, he estimated genetic distance between mutations by measuring

quaternary

in multimeric proteins, different polypeptides bind together in specific ways, known as the protein's ____ structure