Question 1

Which of the following would not be true of cDNA produced using human brain tissue as the starting material?

Accepted Answer

A)  It could be amplified by the polymerase chain reaction. 
B)  It would contain sequences representing all the genes in the genome. 
C)  It was produced from mRNA using reverse transcriptase. 
D)  It could be used as a probe to detect genes expressed in the brain. 
E)  It lacks the introns of the human genes. 
A)  It could be amplified by the polymerase chain reaction. 
B)  It would contain sequences representing all the genes in the genome. 
C)  It was produced from mRNA using reverse transcriptase. 
D)  It could be used as a probe to detect genes expressed in the brain. 
E)  It lacks the introns of the human genes. B

Question 2

The tryptophan operon is a repressible operon that is

Accepted Answer

A)  permanently turned on. 
B)  turned on only when tryptophan is present in the growth medium. 
C)  turned off only when glucose is present in the growth medium. 
D)  turned on only when glucose is present in the growth medium. 
E)  turned off whenever tryptophan is added to the growth medium. 
A)  permanently turned on. 
B)  turned on only when tryptophan is present in the growth medium. 
C)  turned off only when glucose is present in the growth medium. 
D)  turned on only when glucose is present in the growth medium. 
E)  turned off whenever tryptophan is added to the growth medium. E

Question 3

Researchers are looking for better treatments for breast cancer. For a particular DNA microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for a

Accepted Answer

A)  particular gene that is amplified in all or most of the patient samples. 
B)  pattern of fluorescence that indicates which cells are overproliferating. 
C)  pattern shared among some or all of the samples that indicates gene expression differing from control samples. 
D)  group of cDNAs that act differently from those on the rest of the grid. 
E)  group of cDNAs that match those in non-breast-cancer control samples from the same population. 
A)  particular gene that is amplified in all or most of the patient samples. 
B)  pattern of fluorescence that indicates which cells are overproliferating. 
C)  pattern shared among some or all of the samples that indicates gene expression differing from control samples. 
D)  group of cDNAs that act differently from those on the rest of the grid. 
E)  group of cDNAs that match those in non-breast-cancer control samples from the same population. C

Question 4

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

Accepted Answer

A)  Eukaryotic mRNAs get 5' caps and 3' tails. 
B)  Prokaryotic genes are expressed as mRNA, which is more stable in the cell. 
C)  Eukaryotic exons may be spliced in alternative patterns. 
D)  Prokaryotes use ribosomes of different structure and size. 
E)  Eukaryotic coded polypeptides often require cleaving of signal sequences before localization. 
A)  Eukaryotic mRNAs get 5' caps and 3' tails. 
B)  Prokaryotic genes are expressed as mRNA, which is more stable in the cell. 
C)  Eukaryotic exons may be spliced in alternative patterns. 
D)  Prokaryotes use ribosomes of different structure and size. 
E)  Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.

Question 5

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

Accepted Answer

A)  inducer 
B)  promoter 
C)  RNA polymerase 
D)  transcription factor 
E)  cAMP 
A)  inducer 
B)  promoter 
C)  RNA polymerase 
D)  transcription factor 
E)  cAMP

Question 6

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained?

Accepted Answer

A)  As RNAs have evolved since that time, they have taken on new functions. 
B)  Watson and Crick described DNA but did not predict any function for RNA. 
C)  The functions of small RNAs could not be approached until the entire human genome was sequenced. 
D)  Ethical considerations prevented scientists from exploring this material until recently. 
E)  Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible. 
A)  As RNAs have evolved since that time, they have taken on new functions. 
B)  Watson and Crick described DNA but did not predict any function for RNA. 
C)  The functions of small RNAs could not be approached until the entire human genome was sequenced. 
D)  Ethical considerations prevented scientists from exploring this material until recently. 
E)  Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible.

Question 7

Two potential devices that eukaryotic cells use to regulate transcription are

Accepted Answer

A)  DNA methylation and histone amplification. 
B)  DNA amplification and histone methylation. 
C)  DNA acetylation and methylation. 
D)  DNA methylation and histone modification. 
E)  histone amplification and DNA acetylation. 
A)  DNA methylation and histone amplification. 
B)  DNA amplification and histone methylation. 
C)  DNA acetylation and methylation. 
D)  DNA methylation and histone modification. 
E)  histone amplification and DNA acetylation.

Question 8

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

Accepted Answer

A)  DNA supercoiling at or around H1 
B)  methylation and phosphorylation of histone tails 
C)  hydrolysis of DNA molecules where they are wrapped around the nucleosome core 
D)  accessibility of heterochromatin to phosphorylating enzymes 
E)  nucleotide excision and reconstruction 
A)  DNA supercoiling at or around H1 
B)  methylation and phosphorylation of histone tails 
C)  hydrolysis of DNA molecules where they are wrapped around the nucleosome core 
D)  accessibility of heterochromatin to phosphorylating enzymes 
E)  nucleotide excision and reconstruction

Question 9

Which of the following best describes siRNA?

Accepted Answer

A)  a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA 
B)  a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns 
C)  a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor 
D)  a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits 
E)  a molecule, known as Dicer, that can degrade other mRNA sequences 
A)  a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA 
B)  a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns 
C)  a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor 
D)  a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits 
E)  a molecule, known as Dicer, that can degrade other mRNA sequences

Question 10

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

Accepted Answer

A)  irreversible binding of the repressor to the promoter 
B)  reduced transcription of the operon's genes 
C)  buildup of a substrate for the pathway controlled by the operon 
D)  continuous transcription of the operon's genes 
E)  overproduction of catabolite activator protein (CAP) 
A)  irreversible binding of the repressor to the promoter 
B)  reduced transcription of the operon's genes 
C)  buildup of a substrate for the pathway controlled by the operon 
D)  continuous transcription of the operon's genes 
E)  overproduction of catabolite activator protein (CAP)

Question 11

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all.
-Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line?

Accepted Answer

A)  The transgene integrated into a heterochromatic region of the genome. 
B)  The transgene integrated into a euchromatic region of the genome. 
C)  The transgene was mutated during the process of integration into the host cell genome. 
D)  The host cell lacks the enzymes necessary to express the transgene. 
E)  The transgene integrated into a region of the genome characterized by high histone acetylation. 
A)  The transgene integrated into a heterochromatic region of the genome. 
B)  The transgene integrated into a euchromatic region of the genome. 
C)  The transgene was mutated during the process of integration into the host cell genome. 
D)  The host cell lacks the enzymes necessary to express the transgene. 
E)  The transgene integrated into a region of the genome characterized by high histone acetylation.

Question 12

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe.
-In addition, she finds what other evidence of this single-stranded RNA piece's activity?

Accepted Answer

A)  She can measure the degradation rate of the remaining single strand. 
B)  She can measure the decrease in the concentration of Dicer. 
C)  The rate of accumulation of the polypeptide encoded by the target mRNA is reduced. 
D)  The amount of miRNA is multiplied by its replication. 
E)  The cell's translation ability is entirely shut down. 
A)  She can measure the degradation rate of the remaining single strand. 
B)  She can measure the decrease in the concentration of Dicer. 
C)  The rate of accumulation of the polypeptide encoded by the target mRNA is reduced. 
D)  The amount of miRNA is multiplied by its replication. 
E)  The cell's translation ability is entirely shut down.

Question 13

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

Accepted Answer

A)  exploring a way to turn on the expression of pseudogenes 
B)  targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease 
C)  targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease 
D)  creating knock-out organisms that can be useful for pharmaceutical drug design 
E)  looking for a way to prevent viral DNA from causing infection in humans 
A)  exploring a way to turn on the expression of pseudogenes 
B)  targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease 
C)  targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease 
D)  creating knock-out organisms that can be useful for pharmaceutical drug design 
E)  looking for a way to prevent viral DNA from causing infection in humans

Question 14

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called

Accepted Answer

A)  RNA interference. 
B)  RNA obstruction. 
C)  RNA blocking. 
D)  RNA targeting. 
E)  RNA disposal. 
A)  RNA interference. 
B)  RNA obstruction. 
C)  RNA blocking. 
D)  RNA targeting. 
E)  RNA disposal.

Question 15

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
-One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see?

Accepted Answer

A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  activation of histone tails for enzymatic function 
D)  decreased binding of transcription factors 
E)  inactivation of the selected genes 
A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  activation of histone tails for enzymatic function 
D)  decreased binding of transcription factors 
E)  inactivation of the selected genes

Question 16

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

Accepted Answer

A)  the amino acid inactivates the repressor. 
B)  the enzymes produced are called inducible enzymes. 
C)  the repressor is active in the absence of the amino acid. 
D)  the amino acid acts as a corepressor. 
E)  the amino acid turns on transcription of the operon. 
A)  the amino acid inactivates the repressor. 
B)  the enzymes produced are called inducible enzymes. 
C)  the repressor is active in the absence of the amino acid. 
D)  the amino acid acts as a corepressor. 
E)  the amino acid turns on transcription of the operon.

Question 17

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

Accepted Answer

A)  organizing gene expression so that genes are expressed in a given order 
B)  allowing each gene to be expressed an equal number of times 
C)  allowing the organism to adjust to changes in environmental conditions 
D)  allowing young organisms to respond differently from more mature organisms 
E)  allowing environmental changes to alter the prokaryote's genome 
A)  organizing gene expression so that genes are expressed in a given order 
B)  allowing each gene to be expressed an equal number of times 
C)  allowing the organism to adjust to changes in environmental conditions 
D)  allowing young organisms to respond differently from more mature organisms 
E)  allowing environmental changes to alter the prokaryote's genome

Question 18

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for most of the rest?

Accepted Answer

A)  "junk" DNA that serves no possible purpose 
B)  rRNA and tRNA coding sequences 
C)  DNA that is translated directly without being transcribed 
D)  non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function 
E)  non-protein-coding DNA that is transcribed into several kinds of small RNAs without biological function 
A)  "junk" DNA that serves no possible purpose 
B)  rRNA and tRNA coding sequences 
C)  DNA that is translated directly without being transcribed 
D)  non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function 
E)  non-protein-coding DNA that is transcribed into several kinds of small RNAs without biological function

Question 19

In a genome-wide expression study using a DNA microarray assay, each well is used to detect the

Accepted Answer

A)  fate of proteins produced by a cell. 
B)  location of a protein produced by a cell. 
C)  location of a gene within a cell. 
D)  expression of a specific gene by a cell. 
E)  type of chemical modification of proteins produced by a cell. 
A)  fate of proteins produced by a cell. 
B)  location of a protein produced by a cell. 
C)  location of a gene within a cell. 
D)  expression of a specific gene by a cell. 
E)  type of chemical modification of proteins produced by a cell.

Question 20

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
-In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see?

Accepted Answer

A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  activation of histone tails for enzymatic function 
D)  decreased binding of transcription factors 
E)  inactivation of the selected genes 
A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  activation of histone tails for enzymatic function 
D)  decreased binding of transcription factors 
E)  inactivation of the selected genes

Exam 15: Regulation of Gene Expression

Which of the following would not be true of cDNA produced using human brain tissue as the starting material?

The tryptophan operon is a repressible operon that is

Researchers are looking for better treatments for breast cancer. For a particular DNA microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for a

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained?

Two potential devices that eukaryotic cells use to regulate transcription are

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

Which of the following best describes siRNA?

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. -In addition, she finds what other evidence of this single-stranded RNA piece's activity?

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. -One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see?

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

In a genome-wide expression study using a DNA microarray assay, each well is used to detect the

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

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Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Development, Stem Cells, and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

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Plant Structure and Growth

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