homework chp. 11 Flashcards
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
b. test the mutagenic effects of chemicals
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
some of the reversion mutations are not caused by the mutagen being tested
Many chemicals are more mutagenic after being processed in the liver.
a. True
b. False
true
All compounds that have been found to be mutagenic in the Ames test are also carcinogenic.
false
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.
Liver enzymes may activate some innocuous compounds, making them mutagenic.
Which bacteria grow on the agar plate if the Ames test is positive?
his+ prototrophs
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
occur within a restriction enzyme recognition sequence
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
the mutation need not be located within a restriction enzyme recognition site
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
there has been sufficient information gathered on the DNA sequences of both the mutant and normal alleles
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
a base analog that can cause either A-T > G-C or G-C > A-T transitions
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.
DNA with incorporated 5BU must replicate.
In its rare form, 5BU pairs with guanine.
a. True
b. False
true
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.
These dimers distort the DNA structure and result in errors during DNA replication.
Thymine dimers can be repaired by Photoreactivation Repair or Nucleotide Excision Repair.
a. true
b. false
true
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.
Both NER and BER involve the removal of one or more damaged bases by a nuclease.
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
Chromatids of homologous chromosomes
cThe process that determines the length of heteroduplex DNA on the chromatids is called branch migration.
true
Which process does not occur during recombination?
a. Ligation
b. DNA polymerization
c. Strand displacement
d. Nicking of the sugar‑phosphate backbone
b. DNA polymerization
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
cutting DNA at the target sequence
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
Insertion of an IS element within the coding region of a gene
Which repair process in E. coli uses visible light to repair thymine dimers?
photoreactivation repair
Which two repair processes are the most error prone?
translesion DNA synthesis (SOS repair)
non homologous end joining
What kind of DNA lesion does UV energy cause?
pyrimidine dimerization
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?
large genes
regions rich in CpG dinucleotides
long stretches of trinucleotide repeats
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
b. Expansion of trinucleotide repeat sequences
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
b. suppressor mutation
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
c. point mutations
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
a. Ames test
________ 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
d. Tautomers
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
c. Thyminedimers
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
a. nucleotide base analog
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
c. the ability of p53 to bind DNA lesions
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
c. Reduction of p21 synthesis
In the presence of DNA lesions in the cell, the stability of p53 protein increases.
True
False
true
