Module 4 MC

Name two mutagens that would be classified as base analogs. ultraviolet light and cosmic radiation acridine orange and proflavin ethylmethane sulfonate and ethylmethylketone peroxide hydroxyurea and peroxidase 5-bromouracil and 2-aminopurine

5-bromouracil and 2-aminopurine

It is estimated that transposable elements compose approximately what percent of the human genome?

50

What is a mutation? A change in the phenotype A change in allele frequency A change of amino acid A change in the DNA sequence

A change in the DNA sequence

Assume that you wished to generate conditional mutations (such as temperature sensitive mutations) for the study of cell-cycle genes in yeast. Of the mutagens listed in the following, which would be the most likely to generate such mutations? ethyl methane sulfonate (EMS) radiation B and C transposon insertion nitrosoguanidine

B and C

Regulatory proteins that bind DNA have common motifs that interact with sequences of DNA. How do amino acids in DNA-binding proteins interact with DNA? a) and c) By forming covalent bonds with DNA sugars By forming covalent bonds with DNA bases By forming hydrogen bonds with DNA bases None of the above.

By forming hydrogen bonds with DNA bases

Which term most appropriately refers to a regulatory protein in prokaryotes? helicase activation RNA processing translation DNA binding protein gyrase action

DNA binding protein

__________ mutations produce new traits and are usually dominant. Spontaneous Forward Gain-of-function Induced Lethal

Gain-of-function

Riboswitches were first discovered in 2002 and have been found in... archaea In none of the listed organisms In all of the listed organisms fungi plants bacteria

In all of the listed organisms

What is the function of cAMP in regulation of the lac operon? It inactivates a repressor protein. It activates an activator protein. It inactivates an activator protein. It activates a repressor protein.

It activates an activator protein.

E. coli bacteria are placed into a medium containing glucose and lactose. Which of the genes below do you expect to be turned on? Permease Lac I f-galactosidase Lac P None of the above

None of the above

E. coli bacteria are placed into a medium containing glucose and lactose. Which of the genes below do you expect to be turned on? Permease f-galactosidase None of the above Lac I Lac P

None of the above

Which of the following is TRUE for both prokaryotic and eukaryotic gene expression? The mRNA is the exact complement of the gene from which it was copied. mRNA is synthesized in the 3' → 5' direction. After transcription, a 3' poly-A tail and a 5' cap are added to mRNA. RNA polymerase binds to the promoter region to begin transcription.

RNA polymerase binds to the promoter region to begin transcription.

Two modular elements that appear as consensus sequences upstream from RNA polymerase II transcription start sites are enhancers and telomeres. TATA and CAAT. microsatellites and transposons. TTAA and CCTT. rDNA and nucleolar organizers.

TATA and CAAT.

Which of the below is not true about the location of enhancers? They can be found in introns. They can be found downstream of the promoter. They can be found upstream of the transcription initiation site. They can be found 3' of the polyadenylation site. The position of the enhancer has no effect on gene regulation.

The position of the enhancer has no effect on gene regulation.

In what way do upstream activator sequences (UASs), regulatory sequences in yeast, differ from enhancers and silencers? UASs function in the middle of transcription units. UASs only function downstream. UASs can only function in the 5'-3' direction. Enhancers only function downstream. UASs only function upstream.

UASs only function upstream.

Conditional mutations are more likely to result from which of the following alterations to the coding region of a gene. a mutation caused by a base addition a mutation caused by a deletion a mutation caused by a base addition or deletion a mutation caused by X rays a mutation caused by a tautomeric shift

a mutation caused by a tautomeric shift

It is possible for a repressor to negatively regulate the expression of an operon because a. the repressor binding site overlaps the promoter site of the operon allowing it to physically block the binding of RNA polymerase. b. one of the genes expressed in the operon negatively regulates the repressor. c. the repressor induces the expression of inducer. d. the repressor binding site on the DNA overlaps with the translation start site.

a. the repressor binding site overlaps the promoter site of the operon allowing it to physically block the binding of RNA polymerase.

What modification neutralizes the charges on histones that promote ionic interaction with DNA? acetylation phosphorylation demethylation polyadenylation

acetylation

Assuming one mutational event in a gene, on average, which of the following mutagens would be expected to cause the most damage to a protein synthesized by such a mutagenized gene? ethylmethane sulfonate 2-amino purine 5-bromouracil acridine orange

acridine orange

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to alteration of DNA polymerase activity by addition of methyl groups to glycine residues. addition of methyl groups to the cytosine of CG doublets. altering RNA polymerase activity by methylation. changes in DNA-DNA hydrogen binding. altering translational activity especially of highly methylated tRNAs.

addition of methyl groups to the cytosine of CG doublets.

After translation, eukaryotic proteins can be modified by the removal of amino acids. the addition of phosphate groups. all of the above. acetylation. the addition of methyl groups.

all of the above.

In what part of the mRNA does degradation generally begin?

at the 3' end with the removal of the poly(A) tail

Which of the following is NOT true regarding the differences in mRNA between prokaryotic cells and eukaryotic cells? a. In eukaryotic cells, the 3' end of mRNA is modified with a tail, while in porkaryotic cells there is no tail. b. In eukaryotic cells, the transcription to mRNA and the translation from mRNA are coupled, while in prokaryotic cells transcription and translation are not coupled. c. In eukaryotic cells, the 5' end of mRNA is modified with a cap, while in prokaryotic cells there is no cap. d. In eukaryotic cells, mRNA is spliced before translation, while in prokaryotic cells there is no mRNA splicing.

b. In eukaryotic cells, the transcription to mRNA and the translation from mRNA are coupled, while in prokaryotic cells transcription and translation are not coupled.

This question relates to the regulation of enzymes involved in the synthesis of tryptophan in E. coli. If tryptophan is present in the medium and available to the bacterium, a. the five structural genes associated with tryptophan synthesis are being transcribed at "induced" levels. b. the repressor is bound to the operator, thus blocking transcription. c. the repressor is inactive and the tryptophan operon is "on." d. the repressor is inactive and the tryptophan operon is "off." e. positive control is occurring.

b. the repressor is bound to the operator, thus blocking transcription.

Under the system of genetic control of the tryptophan operon, a. no transcription occurs under any nutritional circumstance because negative controls inhibit transcription. b. when there is no tryptophan in the medium, transcription of the trp operon occurs at high levels. c. when there are high levels of tryptophan in the medium, ribosomes "stall" and reduce the levels of tryptophan synthesized. d. when there are high levels of tryptophan in the medium, transcription of CAP (CRP) occurs at high levels. e. when there are high levels of tryptophan in the medium, transcription of the trp operon occurs at high levels.

b. when there is no tryptophan in the medium, transcription of the trp operon occurs at high levels.

The lac repressor protein controls expression of the lac operon via ________________ all of the above binding to the lac operator site to repress expression binding of the lac Z and lac Y genes only binding to the lac promoter site to repress expression binding to the lac structural genes to repress expression

binding to the lac operator site to repress expression

Considering the location of genes in the interphase nucleus, certain chromosomal territories appear to exist. Specifically, a. even-numbered chromosomes are located in the interior of the nucleus, whereas odd-numbered chromosomes are located peripherally. b. gene-poor regions of chromosomes are located outside the nucleus, whereas gene-rich regions are located inside the nucleus. c. each chromosome appears to occupy a discrete domain. d. small chromosomes are more likely to be located in the center of the nucleus. e. large chromosomes are more likely to be located in the center of the nucleus.

c. each chromosome appears to occupy a discrete domain.

When referring to attenuation in regulation of the tryptophan operon, it would be safe to say that when there are high levels of tryptophan available to the organism, a. translational termination is likely. b. the tryptophan operon is being transcribed at relatively high levels. c. transcriptional termination is likely. d. tryptophan is inactivating the repressor protein. e. ribosomes are stalling during translation of the attenuator region.

c. transcriptional termination is likely.

Which of the following clusters of terms applies when addressing enhancers or silencers as elements associated with eukaryotic genetic regulation? trans- and cis-acting, variable position cis-acting, fixed position, fixed orientation trans-acting, fixed position, fixed orientation cis-acting, variable orientation, variable position cis-acting, variable position, fixed orientation

cis-acting, variable orientation, variable position

Nutritional mutations can be defined as a. all strains which are not auxotrophic. b. those mutations which result in changes in behaviour. c. those mutations which change the composition of the medium. d. those mutations which do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium. e. those mutations caused by site-specific mutagenesis

d. those mutations which do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium.

One speaks of UAS (upstream activating sequences) as being DNase hypersensitive. We would interpret this to mean that a. each UAS is likely to be single-stranded. b. any given UAS is composed of a double-stranded site with a bound repressor. c. more than one strand of DNA exists in each UAS. d. each UAS has more histone binding sites than non-UAS sites. e. a UAS is constitutively open.

e. a UAS is constitutively open.

Regulation of gene expression using siRNAs is found in eukaryotes only. prokaryotes and eukaryotes. prokaryotes only.

eukaryotes only.

A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be the following:

frameshift

Under certain conditions, the rate of mutation of a particular gene may be determined in humans. What properties of the mutation would favor the most direct determination of mutation rate in humans? Select all that apply: fully expressed recessive single locus 100% penetrant dominant

fully expressed single locus 100% penetrant dominant

DNA may be damaged from the by-products of normal cellular aerobic respiration. Name three of these electrophilic oxidants that are generally classified as reactive oxidants. carboxyls (COOH-) hydroxyl radicals (·OH) superoxides (O2·-) carbon dioxide (CO2) hydrogen peroxide (H2O2)

hydroxyl radicals (·OH) superoxides (O2·-) hydrogen peroxide (H2O2)

A mutant E. coli strain, grown under conditions that normally induce the lac operon, produces high amounts of ß-galactosidase. What is a possible genotype of the cells? lacI- lacP+ lacO+ lacZ- lacY+ lacA+ lacI+ lacP+ lacO+ lacZ- lacY+ lacA+ lacI+ lacP+ lacOc lacZ+ lacY+ lacA+ lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

lacI+ lacP+ lacOc lacZ+ lacY+ lacA+

A mutant E. coli strain, grown under conditions that normally induce the lac operon, does not produce ß-galactosidase. What is a possible genotype of the cells? lacI+ lacP+ lacOc lacZ+ lacY+ lacA+ lacl+ lacP+ lacO+ lacZ+ lacY+ lacA+ lacI+ lacP+ lacO+ lacZ+ lacY- lacA+ lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

The lac repressor binds to: lactose and DNA. promoter and lactose. RNA polymerase. RNA polymerase and DNA. d-galactosidase, permease and transacetylase.

lactose and DNA.

Which of the following are general categories of mutations? Select all that apply. lethal behavioral protein DNA conditional

lethal behavioral conditional

Which of these are major structural classifications of DNA-binding domains that are found in eukaryotic transcription factors? Please select all that apply: leucine zipper coil-coil helix-turn-helix promoters zinc finger

leucine zipper helix-turn-helix zinc finger

Which of the following are general categories of mutations? Select all that apply. morphological regulatory DNA protein-altering induced

morphological regulatory induced

What term would be applied to a regulatory condition that occurs when protein greatly reduces transcription when associated with a particular section of DNA? positive control stimulation negative control inhibition activation

negative control

An operon is controlled by a repressor. When the repressor binds to a small molecule, it is released from binding to DNA near the operon. The operon is never expressed if a mutation prevents the repressor from binding to the small molecule. negative repressible positive inducible negative inducible positive repressible

negative inducible

Choose the type of control illustrated by each example. E. coli lac operon control by lac I

negative inducible

An operon is controlled by a repressor. When the repressor binds to a small molecule, it binds to DNA near the operon. The operon is constitutively expressed if a mutation prevents the repressor from binding to the small molecule. negative inducible positive inducible positive repressible negative repressible

negative repressible

A _________ mutation changes a codon that specifies an amino acid into one that terminates translation.

nonsense

What term refers to a contiguous genetic complex that is under coordinate control? operon prototroph attenuation lysogen allosteric

operon

A conditional mutation is one that allows a mutant gene product to function normally under the ________ condition, but to function abnormally under the ________ condition. Such mutations are especially useful for the study of ________ mutations. restrictive; permissive; dominant recessive; dominant; codominant dominant; recessive; semidominant permissive; restrictive; dominant permissive; restrictive; lethal

permissive; restrictive; lethal

Which of the following terms best characterizes catabolite repression associated with the lactose operon in E. coli? negative control repressible system inducible system positive control constitutive

positive control

Which of these is a level or type of genetic regulation in eukaryotes? co-transcriptional post-translational transcriptional DNA methylation RNA splicing

post-translational transcriptional DNA methylation

Which of these is a level of regulation in eukaryotes? Select all that apply: operon processing transport transcriptional post-translational

processing transport transcriptional post-translational

What is the general position of the consensus sequence called the GC box? What is its sequence? terminator; GGGCGG promoter; GGGCGG promoter; CAAT terminator; CAAT attenuator; GGGCGG

promoter; GGGCGG

An example of a gene product encoded by a regulatory gene is allolactose. repressor protein. beta-galactosidase enzyme. operator.

repressor protein.

In the lactose operon, the product of structural gene lacZ is capable of replacing hexokinase in the early steps of glycolysis. nonautonomous replication. forming ATP from pyruvate. forming lactose from two glucose molecules. splitting the β-linkage of lactose.

splitting the β-linkage of lactose.

In the lactose operon, the product of structural gene lacZ is capable of splitting the β-linkage of lactose. forming lactose from two glucose molecules. replacing hexokinase in the early steps of glycolysis. nonautonomous replication. forming ATP from pyruvate.

splitting the β-linkage of lactose.

Mutations that arise in nature, from no particular artificial agent, are called

spontaneous mutations.

In general, a "model organism" used in genetics studies is one in which there is a large body of genetic knowledge that has been compiled over decades of genetic research. In addition, model organisms have available their DNA sequences and collections of ________ that make detailed genetic analysis possible and efficient. museum specimens incomplete metamorphic systems epigenetic developmental systems strains with specific mutations complete metamorphic systems

strains with specific mutations

siRNAs and miRNAs are produced by the cleavage of RISCs by endonucleases. the cutting and processing of double-stranded RNA by Slicer enzymes. the cleavage of functional mRNA within the cytoplasm. the cutting and processing of double-stranded RNA by Dicer enzymes. the cleavage of pre-mRNA in the nucleus.

the cutting and processing of double-stranded RNA by Dicer enzymes.

Insulators can block the effects of enhancers only when they lie within a consensus sequence. they lie between an enhancer and a promoter. they lie upstream of a promoter. they lie within the structural genes. they lie adjacent to a promoter.

they lie between an enhancer and a promoter.

Genetic regulation in eukaryotes can take place at a variety of levels from transcriptional to post-translational. At what level is genetic regulation considered most likely in prokaryotes? intron processing polyadenylation of the 3' end of the mRNAs exon processing capping transcriptional

transcriptional

Regarding eukaryotic and prokaryotic genetic regulation, what process seems to be the most similar between the two? intron/exon shuffling poly(A) tail addition transcriptional regulation 5'-capping regulation RNA splicing regulation

transcriptional regulation

An operon is controlled by a repressor. When the repressor binds to Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are called euchromatic and heterochromatic. transversions and transitions. base analogs and frameshift. error prone and spontaneous. sense and antisense.

transversions and transitions.

Considering the electromagnetic spectrum, identify likely mutagens from the following list: radio waves, microwaves, infrared, ultraviolet, X rays, gamma rays, cosmic rays. Select all that apply: microwaves ultraviolet gamma rays cosmic rays radio waves X-rays infrared

ultraviolet gamma rays cosmic rays X-rays

The following may be caused by mobile genetic elements except ________________ cause chromosome breaks all of the above activate a gene in which they reside disrupt a gene undergo mutation

undergo mutation

The difference between a genetic screening experiment and a selection experiment is that a screening experiment involves ________, whereas a selection experiment creates conditions that ________ irrelevant organisms. epistasis analysis; enhance visual examination; eliminate chemical removal; activate temperature extremes; enhance complementation analysis; enhance

visual examination; eliminate

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from muscular dystrophy. phenylketonuria. Huntington disease. xeroderma pigmentosum. SCID.

xeroderma pigmentosum.