Ch.19 gene mutation and DNA repair McGraw hill assignment

Which of these are examples of mutagens?

- 2-Aminopurine - 5-Bromouracil - Nitrous acid - Nitrogen mustard

Which of the following base changes are trans version mutations

- G to C - A to T - A to C

Which changes can cause a frameshift mutation?

- a base deletion -a base addition

The removal of a purine from DNA is called

Depurination

A mutant allele is best defined as an allele that

Has a different DNA sequence from the wild-type

For aa tautomeric shift to cause a mutation, it must occur

Immediately prior to DNA replication

A mutation that results in the death of an organism is known as a(n) _____________ mutation

Lethal

A mutation in a gene that causes an amino acid change in the encoded protein is called a __________ mutation.

Missense

The probability that a gene will be altered by a new mutation is referred to as the

Mutation rate

The enzyme that can recognize thymine diners and split them is called

Photolyase

A(n) _______________ is a type of base substitution that involves a change of a pyrimidine to another pyrimidine, or a purine to another purine

Transition

In a natural population, a ____________-_____________ genotype is the most common one

Wild-type

Which of the following are base analogs?

- 2-aminopurine - 5-bromouracil

Which are examples of somatic mutations?

- a mutation in an adult muscle cell -a mutation in an embryonic kidney cell

The two main mechanisms used to repair DNA double-strand breaks are ____________ recombination repair and ______________ end joining.

- homologous - nonhomologous

Place the steps of homologous recombination repair in the proper sequence. Start with the earliest on top

1) DSB is processed at the break site 2) Strand exchange 3) DNA synthesis 4) Resolution and ligation

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 _____________.

Analogs

Some errors affect individual nucleotides and do not distort the DNA double helix. These errors are removed primarily by a DNA repair system called BER, which stands for _______________ ______________ repair.

Base excision

True or false: During homologous recombination repair, the two broken ends of DNA are pieced back together

FALSE

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

Frameshift

Base analogs induce mutations by

Incorporation into DNA instead of normal bases and tautomerization

Trinucleotide repeat expansions are repeated sequences of three nucleotide bases which

Increase generation after generation

The following proteins participate in mismatch repair. Match the protein with its appropriate function

MutS: Detects the mismatch MutL: Acts as a linker that helps loop the DNA MutH: Makes a cut in nonmethylated strand MutU: Seperates strands at the cleavage site Exonuclease: Digest the nonmethylated strand

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

Nonsense

Some errors create bulky distortions of the double helix. These errors are removed primarily by a DNA repair system called NER, which stands for ______________ ____________ repair.

Nucleotide excision

An imbalance between the production of reactive oxygen species and an organism's ability to break them down is known as

Oxidative stress

During the normal course of DNA replication, the addition of a nucleotide that does not obey the AT/GC rule of base pairing creates a

Base pair mismatch

The region where two chromosome pieces break and re-attach to other chromosome pieces is called a chromosomal _______________.

Breakpoint

The term germ line is used to describe the

Cells that produce sperm and eggs

A silent mutation is a mutation that results in no

Change to the amino acid sequence of the polypeptide

The process by which thymine diners are directly repaired with the help of light is called

Photoreactivation

The expression of an intact gene may be altered when it is moved to a new location. This is due to a(n)_________________.

Position effect

The eye color gene in this Drosophila mutant (panel b) has been relocated to a heterochromatic chromosome, which resulted in its inactivation. This change in the gene's location is said to have a(n) ________________ __________________.

Position effect

Reactive oxygen species (ROS) are

Products of oxygen metabolism in all aerobic organisms

The following are steps in the base excision repair (BER) system. Place them in order

1) N-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 with normal DNA 4) DNA ligase makes a covalent connection in the DNA backbone