homework chp. 11

Question 1

The purpose of the Ames Test is to​ _______.
a. determine whether histidine has mutagenic effects in S. typhimurium
b. test the mutagenic effects of chemicals
c. determine whether Salmonella d. typhimurium​ his- mutants can revert to ​his+
d. study how the liver affects potential mutagens

Answer 1

b. test the mutagenic effects of chemicals

Question 2

In the Ames​ Test, the appearance of his​+ revertants in the presence of a​ non-mutagenic control compound indicates that​ _______.
a. there is some​ low-level contamination in most experiments
b. some of the reversion mutations are not caused by the mutagen being tested
d. the growth medium contains factors that are mildly mutagenic
e. liver extract increases the potency of some mutagens

Answer 2

some of the reversion mutations are not caused by the mutagen being tested

Question 3

Many chemicals are more mutagenic after being processed in the liver.
a. True
b. False

Answer 3

true

Question 4

All compounds that have been found to be mutagenic in the Ames test are also carcinogenic.

Answer 4

false

Question 5

Why are liver extracts used in the Ames​ test?
a. A liver extract is necessary for the bacteria to produce histidine revertants.
b. The bacteria require the nutrients present in the liver extract for growth.
c. Liver enzymes activate the bacterial enzymes.
d. Liver enzymes may activate some innocuous​ compounds, making them mutagenic.

Answer 5

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

Question 6

Which bacteria grow on the agar plate if the Ames test is​ positive?

Answer 6

his​+ prototrophs

Question 7

To use RFLP analysis to detect a​ SNP, the SNP must​ _______.
a. be present in at least​ 1% of the population
b. occur in homozygous form
c. cause disease
d. occur within a restriction enzyme recognition sequence

Answer 7

occur within a restriction enzyme recognition sequence

Question 8

One advantage of​ allele-specific oligonucleotide​ (ASO)-based over​ RFLP-based detection of human genetic disease is that​ _______.
​a. ASO-based methods can identify heterozygotes as well as homozygotes
​b. RFLP-based methods require electrophoresis
​c. ASO-based methods can detect mutations as small as a single nucleotide
d. the mutation need not be located within a restriction enzyme recognition site

Answer 8

the mutation need not be located within a restriction enzyme recognition site

Question 9

Molecular tests for​ Huntington’s disease, cystic​ fibrosis, and​ Tay-Sachs disease are possible because​ _______.
a. there has been sufficient information gathered on the DNA sequences of both b. the mutant and normal alleles
these diseases occur in greater than​ 1% of the population
c. the symptoms of these diseases are well documented
d. the chromosome on which each gene is located is known

Answer 9

there has been sufficient information gathered on the DNA sequences of both the mutant and normal alleles

Question 10

In terms of its involvement in​ mutagenesis, 5BU is best described as​ _______.
a. a chemical that alters the structure of nitrogenous bases
b. a base analog that can cause either​ A-T >​ G-C or​ G-C >​ A-T transitions
Your answer is correct.
c. a rare form of adenine that can base pair with cytosine
d. a base analog​ that, if incorporated into a DNA molecule during​ replication, remains permanently in its rare form

Answer 10

a base analog that can cause either​ A-T >​ G-C or​ G-C >​ A-T transitions

Question 11

For 5BU to cause a transition​ mutation, which of the following must​ occur?
a. It must be incorporated into DNA in its rare form.
b. It must undergo at least two form changes.
c. DNA with incorporated 5BU must replicate.
d. DNA with incorporated 5BU must not replicate.

Answer 11

DNA with incorporated 5BU must replicate.

Question 12

In its rare​ form, 5BU pairs with guanine.
a. True
b. False

Answer 12

true

Question 13

What are the consequences of having pyrimidine dimers in​ DNA?
a. They form an extra phosphodiester bond between them.
b. These dimers distort the DNA structure and result in errors during DNA replication.
c. They create an apyrimidinic site
d. They prevent the transcription of the DNA into RNA.

Answer 13

These dimers distort the DNA structure and result in errors during DNA replication.

Question 14

Thymine dimers can be repaired by Photoreactivation Repair or Nucleotide Excision Repair.
a. true
b. false

Answer 14

true

Question 15

Which of the following statements regarding Nucleotide Excision Repair​ (NER) and Base Excision Repair​ (BER) is​ true?
a. Only NER involves the action of DNA ligase to seal nicks in the DNA backbone.
b. Both NER and BER can be activated by exposure to visible light.
c. Both NER and BER involve the creation of an apyrimidinic​ (AP) site.
d. Both NER and BER involve the removal of one or more damaged bases by a nuclease.

Answer 15

Both NER and BER involve the removal of one or more damaged bases by a nuclease.

Question 16

Which structures can be involved in​ recombination?
a. Chromatids of homologous chromosomes
b. Chromosomes in different cells
c. Any two chromosomes
d. Chromatids of nonhomologous chromosomes

Answer 16

Chromatids of homologous chromosomes

Question 17

cThe process that determines the length of heteroduplex DNA on the chromatids is called branch migration.

Answer 17

true

Question 18

Which process does not occur during​ recombination?
a. Ligation
b. DNA polymerization
c. Strand displacement
d. Nicking of the​ sugar‑phosphate backbone

Answer 18

b. DNA polymerization

Question 19

All of the following are characteristics of insertion sequences elements except​ _______.
a. they encode protein
b. they are flanked by inverted repeats
c. a copy of the insertion sequence becomes integrated at a new location
d. there can be more than one copy of an IS element in a bacterial genome

Answer 19

cutting DNA at the target sequence

Question 20

Which of the following transposition events is most likely to result in a loss of function​ mutation?
a. Insertion near the promoter region of a gene
b. Transposition of an IS element that contains a stop codon within the inverted repeat sequence
c. Insertion of an IS element within the coding region of a gene

Answer 20

Insertion of an IS element within the coding region of a gene

Question 21

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

Answer 21

photoreactivation repair

Question 22

Which two repair processes are the most error​ prone?

Answer 22

translesion DNA synthesis (SOS repair)
non homologous end joining

Question 23

What kind of DNA lesion does UV energy​ cause?

Answer 23

pyrimidine dimerization

Question 24

The three features of genes or of DNA sequences that contribute to the occurrence of mutational hotspots were described in chapter 12 in the textbook.
what are they?

Answer 24

large genes
regions rich in CpG dinucleotides
long stretches of trinucleotide repeats

Question 25

Which of the following spontaneous mutations alters DNA​ structure/sequence and generally results from strand​ slippage? See Section 11.2.
a. Tautomeric shift that changes the structure of a base
b. Expansion of trinucleotide repeat sequences
c. Deamination of cytosine
d. Depurination

Answer 25

b. Expansion of trinucleotide repeat sequences

Question 26

A​ second-site mutation that compensates for the mutation in one gene by mutating a second gene and restoring the​ wild-type phenotype is also known as a​ ________ .
a. intragenic reversion
b. suppressor mutation
c. true reversion
d. forward mutation

Answer 26

b. suppressor mutation

Question 27

Localized mutations that occur at a specific​ location, rather than over a larger span on a gene are better known as​ what?
​a. base-pair substitution mutations
b. frameshift mutation
c. point mutations
d. adaptive mutations

Answer 27

c. point mutations

Question 28

A manufacturer of nutritional supplements proposes to sell extracts from an Antarctic algae as an ingestible remedy for sleep disorders. Your task is to determine if this extract may be​ mutagenic, how do you test​ this?
a. Ames test
b. with alkylating agents
c. with UV radiation
d. fluctuation test

Answer 28

a. Ames test

Question 29

​________ are structures that have the same composition and general arrangement but a slight difference in bonding and placement of a hydrogen.
a. Mispairs
b. Frameshifts
c. Hotspots
d. Tautomers

Answer 29

d. Tautomers

Question 30

Which type of DNA damage is repaired by the enzyme​ photolyase? See Section 11.4.
a. Apurinic sites
b. Methylated or alkylated bases
c. Thyminedimers
​d. Single-strand breaks in the DNA backbone

Answer 30

c. Thyminedimers

Question 31

Which type of mutagen has a structure similar to one of the DNA nucleotides and therefore can work its way into​ DNA, where it pairs with a​ nucleotide?
a. nucleotide base analog
b. deaminating agent
c. hydroxylating agent
d. alkylating agent

Answer 31

a. nucleotide base analog

Question 32

The role that p53 protein plays in suppressing inappropriate progression through the cell cycle depends on all of the following EXCEPT​ _______.
a. p53 indirectly blocks G1 to S transition in the cell cycle
b. p53 stability increases in the presence of unrepaired DNA lesions
c. p53 activates transcription of WAF1
c. the ability of p53 to bind DNA lesions

Answer 32

c. the ability of p53 to bind DNA lesions

Question 33

Which of the following is a consequence of inactivation of both p53 alleles in a​ cell?
a. Programmed cell death​ (apoptosis) of the cell
d. A reduction in kinase activity of the​ cyclin-Cdk complex
c. Reduction of p21 synthesis
d. Relative instability of the​ non-functional protein

Answer 33

c. Reduction of p21 synthesis

Question 34

In the presence of DNA lesions in the​ cell, the stability of p53 protein increases.
True
False

Answer 34

true