Genetics Lesson 18

frameshift mutations

Acridine *dyes* cause?

oxidative stress

An *imbalance* between the *production* of *reactive* *oxygen* *species* and an *organisms* *ability* to *break* them *down* is known as?

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 ____.

being incorporated instead of normal bases during DNA replication

*Base* *analogs* *induce* mutations by?

abnormal bases

*Base* *excision* *repair* (BER) is the *main* *system* used in the *repair* of?

1. spontaneous, 2. induced

*Mutations* can be cause in *two* *main* ways: 1. ______ mutations are the result of *natural* *biological* or *chemical* *processes*; and 2. ____ mutations are produced by *environmental* *agents*.

can directly split a thymine dimer in the presence of light

*Photoreactivation* is a *repair* *mechanism* that?

which increase generation after generation

*Trinucleotide* *repeat* *expansions* are repeated sequence of three bases which?

nonhomologous end joining, homologous recombination repair

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

bulky, helix distorting lesions

*nucleotide* *excision* *repair* (NER) is the *main* *system* used in *repair* of?

where two chromosome pieces break and rejoin with other chromosome pieces

A *breakpoint* refers to the *region*?

point

A *change* in a *single* *base* *pair* in the genetic material is known as a(n) _____ mutation.

mutation

A *heritable* change in the genetic material is called a(n)?

agent that causes mutations

A *mutagen* is a(n)?

has a different DNA sequence from the wild type

A *mutant* *allele* is *best* *defined* as an allele that?

no change to the amino acid sequence of the DNA

A *silent* *mutation* is a mutation that results in?

missense

A base substitution in DNA that ultimately leads to a *change* in the *encoded* *amino* *acid* is called a(n) _________ mutation.

missense

A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) ________ mutation.

lethal

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

silent

A mutation that does *not* *change* the *amino* *acid* *sequence* of a *polypeptide* is known as a(n) ______ mutation.

nonsense

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

point

A(n) _____ mutation refers to a mutation in which *just* one base is *changed* within the *DNA* *sequence*.

transition

A(n) ________ is a type of *base* *substitution* that involves a *change* of the *pyrimidine* to another *pyrimidine* , or a *purine* to another*purine*.

nucleotide excision

Some errors create *bulky* *distortions* of the *double* *helix*. These errors are *removed* *primarily* by a DNA repair system called *NER*, which strands for ______ _____repair,

frameshift

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

double-strand

The *breakage* of *chromosomes* is referred to as a(n) _______-______ break.

the Ames test

Which of these tests is used to *evaluate* the *mutagenicity* of an *agent*?

spontaneous; induced

Errors in DNA replication are examples of ______ mutations, while mutations caused by ultraviolet light are _______ mutations.

adult muscle cell, embryonic kidney cell, brain cell

Examples of *somatic* *mutations* include a mutation occurring in a(n)?

myotonic, fragile

Examples of *trinucleotide* *repeat* *expansion* (TRNE) disorders include _____ muscular dystrophy and _____ X syndrome.

immediately prior to DNA replication

For a *tautomeric* *shift* to *cause* a *mutation*, it *must* occur?

depurination

The *removal* of a *purine* from *DNA* is called _______.

deamination

The *removal* of an *amino* *group* from a *base* is called?

typically found in nature

The *wild* *type* *genotype* or *phenotype* is the one that is?

photolyase

The enzyme that can *recognize* *thymine* *dimers* and *split* them is called ______?

the cells that produce sperm and eggs

The term *germ* *line* is used to describe?

nucleotide deletion, nucleotide addition

What can *cause* a *frameshift* *mutation*?

x-rays, gamma rays, reactive oxygen species

What can cause *double-stranded* *breaks* (DSBs)?

photolyase

Which enzyme can correct the mutation shown in this figure?

enol, imino, keto, amino

Which of the following are forms of *tautomers*?

reactive oxygen species

*oxidative* *DNA* *damage* refers to *changes* in *DNA* *structure* that are caused by?

products of oxygen metabolism in all aerobic organisms

*reactive* *oxygen* *species* (ROS) are?

frameshift

Which type of mutation occurs in line 4?

MutS

Which protein that participates in mismatch repair *detects* the *mismatch*?

Exonuclease

Which protein that participates in mismatch repair *digests* the *nonmethylated* *strand*?

MutU

Which protein that participates in mismatch repair *separates* *strands* at the *cleavage* *site*?

MutL

Which protein that participates in mismatch repair acts as a *linker* that *helps* loop* the *DNA*?

MutH

Which protein that participates in mismatch repair makes a *cut* in a *nonmethylated* *strand*?

silent

Which type of mutation occurs in line 1?

Missense

Which type of mutation occurs in line 2?

nonsense

Which type of mutation occurs in line 3?

1. DSB is processed at the break site 2. strand exchange 3. DNA synthesis 4. resolution and ligation

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

base excision

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.

position effect

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

ultraviolet light

Thymine dimers are typically caused by?

a to c, g to c, a to t

Which of the following base changes are *transversion* *mutations*?

includes ultraviolet light, contains low energy

Which of the following statements about *nonionizing* *radiation* are *true*?

Up promoter mutations cause the promoter sequence to be more like the consensus sequence. Down promoter mutations decrease the affinity of transcription factors to the promoter

Which of the following statements about *promoter* *mutations* is true?

homologous, nonhomologous

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

base substitution

This figure best illustrates what type of mutation?

nonhomologous end joining

This figure shows the first step of the *mechanism* of *DNA* *repair* called?

break point

The *region* where *two* *chromosome* pieces*break* and *reattach* to other chromosome pieces is called a chromosomal ____.

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 back bone. 3. DNA polymerase removes the damaged DNA and replaces it with normal DNA. 4. DNA ligase makes a covalent connection in the DNA backbone

The following are steps in the *base* *excision* *repair* (BER) *system*. Place them in order, starting with the *earliest* on top.

1, UvrA/UrvB complex tracks along the DNA in search of damaged DNA. 2. UvrA is released and UvrC binds. 3.UvrC makes cuts on both sides of the thymine dimer. 4.UvrD removes the damaged region. 5. UvrB and UvrC are released. 6. DNA polymerase fills the gap and DNA ligase seals the region.

The following steps in the nucleotide excision repair (NER) system. Place them in order, starting with the earliest on top?

depurinations

Mutations that *remove* an *adenine* or *guanine* from the *DNA* are known as?

position effect

The *eye* *color* *gene* in the *Drosophila* *mutant* (panel B) has been *relocated* to a *heterochromatic* *chromosomal* *region*, which results in its *inactivation* in some cells, causing *variegated* *appearance*. This *change* in the gene's *location* is said to have a(n).

in a given gene per cell generation

The *mutation* *rate* is commonly expressed as the *number* of *new* *mutations*...

mutation rate

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

high energy, gamma rays, short wavelength

Which of the following terms is associated with *ionizing* *energy*?

Fragile X syndrome, myotonic muscular dystrophy, huntington disease

Which of these are *trinucleotide* *repeat* *expansion* disorders?

ethyl methanesulfonate, nitrogen mustard

Which of these are examples of *alkylating* *agents*?

2-Aminopurine, nitrous acid, nitrogen mustard, 5-bromouracil

Which of these are examples of *mutagens*?

catalase, vitamin C, superoxide dismutase

Which of these are used by *cells* to *limit* the *harmful* *effects* of *reactive* *oxygen* *species*?

detection removal replication

Which of these represents the correct order of steps during a typical *DNA* *repair* *system*?