Genetics Test 5

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene? a. an insertion of three nucleotides near the end of gene b a base substitution at the end of the gene c. a base substitution at the beginning of the gene d. a frameshift insertion near the polyadenylation site of the gene e. a frameshift deletion (2 bases) at the beginning of the gene

a frameshift deletion (2 bases) at the beginning of the gene

It has been observed that diseases caused by repeat expansions are the result of trinucleotide repeats rather than smaller or larger repeat lengths. If NON-trinucleotide repeat expansions were present in the coding region of a gene, which type of mutation would you expect to be the most likely? a. terminal deletion b silent c. frameshift d. missense e. nonsense

frameshift

I-P+O+Z+Y+

is lac + and the genes are constitutively transcribed

I+P+O+Z+Y+

is lac+ and the genes are inducibly transcribed

I+P+OCZ-Y+

is lac- and the genes are constitutively transcribed

I+P+O+Z-Y+

is lac- and the genes are inducibly transcribed

ISP+O+Z+Y-

is lac- and the genes are not transcribed

Translation of the thiMD operon genes in E. coli occurs when a. low TP leads to the formation of a Shine-Dalgarno antisequestor stem loop b. high TP concentration initiates the riboswitch that leads to intrinsic termination c. low TPP concentration leads to the formation of an antitermination stem-loop d. high TP concentration leads to the formation of an antitermination stem-loop e. low TPP concentration leads to the formation of a riboswitch to initiate transcription

low TP leads to the formation of a Shine-Dalgarno antisequestor stem loop

To use RFLP analysis to detect a SNP, the SP must a. be present in at least 11% of the population b. occur in heterozygous form c. occur within a restriction enzyme recognition sequence d. cause disease e. occur within a the sequence of a transposon

occur within a restriction enzyme recognition sequence

What mRNA is expressed at elevated growth temperatures, leading to transcription of heat shock genes? a. rpoH b Cro c. IS10 d. glmS e. sigma70

rpoH

Two different mutations are identified in a haploid strain of yeast: The first prevents the synthesis of adenine by a nonsense mutation of the ade-1 gene. In this mutation, a base-pair substitution changes a tryptophan codon (UGG) to a stop codon (UGA). The second affects one of several duplicate tRNA genes. This base-pair substitution mutation changes the anticodon sequence of a tRNAtrp from 3'-ACC-5' to 3'-ACU-5'. What term would best be used to describe the second mutation? a. nonsense mutation b. suppressor mutation c. reverse mutation d. intragenic reversion e. forward mutation

suppressor mutation

The purpose of the Ames Test is to a. determine whether histidine has mutagenic effects in S. typhimurium b. study how the liver affects potential mutagens C. Oh man, I forgot to study the Ames test... d. test the mutagenic effects of chemicals e. determine whether Salmonella typhimurium his- mutants can revert to his+

test the mutagenic effects of chemicals

Which type of DNA damage is repaired by the enzyme photolyase? a. alkylation of bases b. apurinic sites c. double-strand breaks d. single-strand breaks e. thymine dimers

thymine dimers

State the full names of the two types of Double-stranded Break Repair discussed in Ch 11 (not just the acronyms).

Homology-directed repair Non homologous end joining

___________ is an inhibitor of apoptosis in healthy cells that can be directly inhibited by ___________ in cells with DNA damage. a. BAX, p21 b. BCL2, p21 c. RecA. RuvB d. p21, p53 e. BCL2, BAX

BCL2, BAX

_______ are molecules that have the same composition and general arrangement but a slight difference in bonding and placement of a hydrogen.

Tautomers

Ataxia telangiectasia (OMIM 208900) is a human inherited disorder characterized by poor coordination (ataxia), red marks on the face (telangiectasia), increased sensitivity to X-rays and other radiation, and an increased susceptibility to cancer. Recent studies have shown that this disorder occurs as a result of mutation of the ATM gene. ATM is a protein kinase that is activated in response to DNA damage and then activates other proteins that cause cell cycle arrest and/or apoptosis. Which of the following explains why DNA repair mechanisms cannot correct this problem a. A loss of ATM means you can no longer access your money. b. A loss of ATM function cannot be overcome by the action of DNA repair pathways because this mutation is permanent. c. A loss of ATM function cannot be overcome by the action of DNA repair pathways because cells enter S-phase before there is enough time for DNA repair. d A loss of ATM function cannot be overcome by the action of DNA repair pathways because the cell starts apoptosis. e. A loss of ATM function cannot be overcome by the action of DNA repair pathways because enzymes for this process become blocked.

A loss of ATM function cannot be overcome by the action of DNA repair pathways because cells enter S-phase before there is enough time for DNA repair.

Which of the following is true of the partial diploid cell below IsP+OcZ-Y+ / I-P+O+Z-Y+ a. I was really hoping you wouldn't ask this one Dr. Trott b. Beta-galactosidase would be constitutively transcribed and permease would be inducible C. both Beta-galactosidase and permease would be constitutively expressed d. Beta-galactosidase would be uninducible and permease would be constitutively expressed e. Beta-galactosidase would be constitutively transcribed and permease would be non-inducible

Beta-galactosidase would be uninducible and permease would be constitutively expressed

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

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

What type of damage results in an apurinic (AP) site? a. Breaking the covalent bond at the 1' carbon of deoxyribose in a purine. b. Replacing the hydrogen atom at the 5' carbon with a CH3 (methyl) group. C. Breaking the covalent bond at the 4' carbon of deoxyribose in a pyrimidine. d. Breaking the covalent bond at the 5' carbon of deoxyribose in a purine. e. Breaking the covalent bond at the 4' carbon of deoxyribose in a pyrimidine

Breaking the covalent bond at the 1' carbon of deoxyribose in a purine

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

Expansion of trinucleotide repeat sequences

Name any one of the Trinucleotide repeat disorders mentioned in class.

Huntington's disease

In mismatch repair in E. coli. The MutH/L/S system uses nearby 5'-GATC'3' sequences. Which of the following modifications is common on this sequence? a. Methylation on the Guanine b None of these are correct c. Methylation on the Adenine d. apurinic sites on the Guanine or Adenine e Ethylation on the Thymine

Methylation on the Adenine

Which of the following conditions would induce the lytic cycle in Lambda phage infected E. coli cells? a. Mutating the N protein in a way that prevents its binding to DNA b. Mutating the cl gene in a way that causes its protein product to bind to DNA more strongly c. Higher levels of cl than cro in the cell d. Large number of co-infecting phage e. Poorly growing bacterial host population

Mutating the N protein in a way that prevents its binding to DNA

Which transposable element in bacteria lacks insertion sequences? a. Ty elements b Try elements C. I don't know yet....:) d. Non-composite transposons e. Composite transposons

Non-composite transposons

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

Photoreactive repair

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

Reduction of p21 synthesis

Which of the following occurs as a result of an abundance of tryptophan in E. coll? a. The 5 trp genes (TrpA - TrpE) are transcribed, but not translated. b. The leader sequence is not transcribed. C. The leader sequence is duplicated d. The 5 trp genes (TrpA - TrpE) are not transcribed. e. Stalling of the ribosome at trp codons in the leader sequence

The 5 trp genes (TrpA - TrpE) are not transcribed.

The CAP binding site in the lac promoter is the location of positive regulation of gene expression for the operon. How does the binding exert a positive effect? a. CAP interacts with Tup-1 to prevent transcription in the presence of Glucose b. The CAP-cAMP complex alters the structure of the promoter and allows RNA polymerase to bind to it. c. The CAP-cAMP complex prevents the binding of the repressor protein. d. The CAP-cAMP complex triggers the formation of the DNA loop, which prevents binding of the repressor protein. e. The CAP-cAMP complex unbends the DNA loop, thereby allowing binding of RNA polymerase.

The CAP-cAMP complex alters the structure of the promoter and allows RNA polymerase to bind to it.

What would happen to the expression of the lac operon a bacterial cell if you mutated the enzyme adenylate cyclase in a way that caused it to make cAMP constitutively? a. The lactose operon would be expressed at high levels in response to lactose in the presence and/or absence of glucose b. The lactose operon would be non-inducible even in the presence of lactose c. The lactose operon would be constitutively expressed even in the absence of lactose d. The lactose operon would be non-inducible except for in the presence of glucose e. The lactose operon would be expressed at high levels in response to lactose but only in the absence of glucose

The lactose operon would be expressed at high levels in response to lactose in the presence and/or absence of glucose

If the UGG codons in Region 1 of trpL were changed to AGG codons, what effect would this have on expression of the trpoperon? a. The operon would be constitutively expressed. b. The operon would be regulated by tryptophan, but attenuation would be triggered at higher levels of tryptophan than in wild type. c. The operon would be regulated by tryptophan, but attenuation would be triggered at lower levels of tryptophan than in wild type. d. The operon would never be expressed. e. The operon would be regulated by arginine levels; high levels of arginine would attenuate expression of trp genes.

The operon would be regulated by arginine levels; high levels of arginine would attenuate expression of trp genes.

Which of the following features of the trp operon is likely least essential to the process of attenuation? a. The order of the structural genes, E, D, C, B, A b. Trp codons near the beginning of the leader sequence C. The ability of sequences within the leader mRNA to pair with one another d. Transcription and translation of the leader sequence occur simultaneously.

The order of the structural genes, E, D, C, B, A