Question 1

Under what conditions does the trp repressor block transcription of the trp operon?

Accepted Answer

A)  when the repressor binds to the inducer 
B)  when the repressor binds to tryptophan 
C)  when the repressor is not bound to tryptophan 
D)  when the repressor is not bound to the operator 
A)  when the repressor binds to the inducer 
B)  when the repressor binds to tryptophan 
C)  when the repressor is not bound to tryptophan 
D)  when the repressor is not bound to the operator

Question 2

Which of the following molecules helps to "turn off" genes in a cell?

Accepted Answer

A)  operon 
B)  inducer 
C)  promoter 
D)  corepressor 
A)  operon 
B)  inducer 
C)  promoter 
D)  corepressor

Question 3

When the Bicoid protein is expressed in Drosophila, divisions between cells in the embryo are not yet fully developed. This information helps to explain which observation by Nüsslein-Volhard and Wieschaus?

Accepted Answer

A)  mRNA from the egg is translated into the Bicoid protein. 
B)  Bicoid protein diffuses throughout the embryo in a concentration gradient. 
C)  Bicoid protein serves as a transcription regulator. 
D)  Bicoid protein determines the dorso-ventral axis of the embryo. 
A)  mRNA from the egg is translated into the Bicoid protein. 
B)  Bicoid protein diffuses throughout the embryo in a concentration gradient. 
C)  Bicoid protein serves as a transcription regulator. 
D)  Bicoid protein determines the dorso-ventral axis of the embryo.

Question 4

How are bacteria able to change their patterns of protein synthesis so quickly in response to environmental changes?

Accepted Answer

A)  mRNAs that are produced are short-lived and degraded within a few minutes of being synthesized. 
B)  mRNA have long lifespans, allowing the bacteria to use them many times for translation. 
C)  mRNA is stored for later use. 
D)  Operons are activated in the presence of transcription factors. 
A)  mRNAs that are produced are short-lived and degraded within a few minutes of being synthesized. 
B)  mRNA have long lifespans, allowing the bacteria to use them many times for translation. 
C)  mRNA is stored for later use. 
D)  Operons are activated in the presence of transcription factors.

Question 5

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, she succeeded in increasing acetylation of histone tails in the chromatin of the cells. Which of the following results would she most likely see in these cells?

Accepted Answer

A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  decreased binding of transcription factors 
D)  inactivation of the selected genes 
A)  increased chromatin condensation 
B)  decreased chromatin condensation 
C)  decreased binding of transcription factors 
D)  inactivation of the selected genes

Question 6

In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated?

Accepted Answer

A)  genes coding for enzymes that act in the colon 
B)  genes involved in control of the cell cycle 
C)  genes that are especially susceptible to mutation 
D)  genes of the bacteria, which are abundant in the colon 
A)  genes coding for enzymes that act in the colon 
B)  genes involved in control of the cell cycle 
C)  genes that are especially susceptible to mutation 
D)  genes of the bacteria, which are abundant in the colon

Question 7

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

Accepted Answer

A)  Proto-oncogenes first arose from viral infections. 
B)  Proto-oncogenes are mutant versions of normal genes. 
C)  Proto-oncogenes are genetic "junk." 
D)  Proto-oncogenes normally help regulate cell division. 
A)  Proto-oncogenes first arose from viral infections. 
B)  Proto-oncogenes are mutant versions of normal genes. 
C)  Proto-oncogenes are genetic "junk." 
D)  Proto-oncogenes normally help regulate cell division.

Question 8

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 
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

Question 9

Which of the following types of mutation would convert a proto-oncogene into an oncogene?

Accepted Answer

A)  a mutation that blocks transcription of the proto-oncogene 
B)  a mutation that creates an unstable proto-oncogene mRNA 
C)  a mutation that greatly increases the amount of the proto-oncogene protein 
D)  a deletion of most of the proto-oncogene coding sequence 
A)  a mutation that blocks transcription of the proto-oncogene 
B)  a mutation that creates an unstable proto-oncogene mRNA 
C)  a mutation that greatly increases the amount of the proto-oncogene protein 
D)  a deletion of most of the proto-oncogene coding sequence

Question 10

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If a researcher moves the operator to the far end of the operon, past the transacetylase (lacA)gene, which of the following processes would likely occur when the cell is exposed to lactose?

Accepted Answer

A)  The inducer will no longer bind to the repressor. 
B)  The repressor will no longer bind to the operator. 
C)  The operon will never be transcribed. 
D)  The genes of the lac operon will be transcribed continuously. 
A)  The inducer will no longer bind to the repressor. 
B)  The repressor will no longer bind to the operator. 
C)  The operon will never be transcribed. 
D)  The genes of the lac operon will be transcribed continuously.

Question 11

How does extracellular glucose inhibit transcription of the lac operon?

Accepted Answer

A)  by strengthening the binding of the repressor to the operator 
B)  by weakening the binding of the repressor to the operator 
C)  by inhibiting RNA polymerase from opening the strands of DNA to initiate transcription 
D)  by reducing the levels of intracellular cAMP 
A)  by strengthening the binding of the repressor to the operator 
B)  by weakening the binding of the repressor to the operator 
C)  by inhibiting RNA polymerase from opening the strands of DNA to initiate transcription 
D)  by reducing the levels of intracellular cAMP

Question 12

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. Many people were surprised that the number of protein-coding sequences was much smaller than they had expected. Which of the following types of DNA make up the rest of the human genome?

Accepted Answer

A)  DNA that consists of histone coding sequences 
B)  DNA that is translated directly without being transcribed 
C)  non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function 
D)  non-protein-coding DNA that serves as binding sites for reverse transcriptase 
A)  DNA that consists of histone coding sequences 
B)  DNA that is translated directly without being transcribed 
C)  non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function 
D)  non-protein-coding DNA that serves as binding sites for reverse transcriptase

Question 13

Why are BRCA1 and BRCA2 considered to be tumor-suppressor genes?

Accepted Answer

A)  Their normal products participate in repair of DNA damage. 
B)  The mutant forms of either one of these prevent breast cancer. 
C)  The normal genes make estrogen receptors. 
D)  They block penetration of breast cells by chemical carcinogens. 
A)  Their normal products participate in repair of DNA damage. 
B)  The mutant forms of either one of these prevent breast cancer. 
C)  The normal genes make estrogen receptors. 
D)  They block penetration of breast cells by chemical carcinogens.

Question 14

Muscle cells differ from nerve cells mainly because they

Accepted Answer

A)  express different genes. 
B)  contain different genes. 
C)  use different genetic codes. 
D)  have unique ribosomes. 
A)  express different genes. 
B)  contain different genes. 
C)  use different genetic codes. 
D)  have unique ribosomes.

Question 15

Which of the following statements describes a cell that is considered to be differentiated?

Accepted Answer

A)  The cell replicates by the process of mitosis. 
B)  The cell loses connections to the surrounding cells. 
C)  The cell produces proteins specific to a particular cell type. 
D)  The cell appears to be different from the surrounding cells. 
A)  The cell replicates by the process of mitosis. 
B)  The cell loses connections to the surrounding cells. 
C)  The cell produces proteins specific to a particular cell type. 
D)  The cell appears to be different from the surrounding cells.

Question 16

Which of the following molecules are involved in pattern formation during development?

Accepted Answer

A)  cytoplasmic determinants 
B)  miRNAs 
C)  cAMP 
D)  transcription factors 
A)  cytoplasmic determinants 
B)  miRNAs 
C)  cAMP 
D)  transcription factors

Question 17

How does the transcription of structural genes in an inducible operon occur?

Accepted Answer

A)  It occurs continuously in the cell. 
B)  It starts when the pathway's substrate is present. 
C)  It starts when the pathway's product is present. 
D)  It stops when the pathway's product is present. 
A)  It occurs continuously in the cell. 
B)  It starts when the pathway's substrate is present. 
C)  It starts when the pathway's product is present. 
D)  It stops when the pathway's product is present.

Question 18

Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?

Accepted Answer

A)  Enhancers are transcription factors; proximal control elements are DNA sequences. 
B)  Enhancers improve transcription; proximal control elements inhibit transcription. 
C)  Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter. 
D)  Enhancers are DNA sequences; proximal control elements are proteins. 
A)  Enhancers are transcription factors; proximal control elements are DNA sequences. 
B)  Enhancers improve transcription; proximal control elements inhibit transcription. 
C)  Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter. 
D)  Enhancers are DNA sequences; proximal control elements are proteins.

Question 19

Which of the following processes destroys RNA molecules in a cell if they have a sequence complementary to an introduced double-stranded RNA?

Accepted Answer

A)  RNA interference 
B)  RNA obstruction 
C)  RNA blocking 
D)  RNA disposal 
A)  RNA interference 
B)  RNA obstruction 
C)  RNA blocking 
D)  RNA disposal

Question 20

What essential information does the product of the bicoid gene in Drosophila provide during development?

Accepted Answer

A)  orientation of the dorsal-ventral axis 
B)  orientation of the left-right axis 
C)  segmentation 
D)  orientation of the anterior-posterior axis 
A)  orientation of the dorsal-ventral axis 
B)  orientation of the left-right axis 
C)  segmentation 
D)  orientation of the anterior-posterior axis

Exam 18: Regulation of Gene Expression

Under what conditions does the trp repressor block transcription of the trp operon?

Which of the following molecules helps to "turn off" genes in a cell?

When the Bicoid protein is expressed in Drosophila, divisions between cells in the embryo are not yet fully developed. This information helps to explain which observation by Nüsslein-Volhard and Wieschaus?

How are bacteria able to change their patterns of protein synthesis so quickly in response to environmental changes?

In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated?

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

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

Which of the following types of mutation would convert a proto-oncogene into an oncogene?

How does extracellular glucose inhibit transcription of the lac operon?

Why are BRCA1 and BRCA2 considered to be tumor-suppressor genes?

Muscle cells differ from nerve cells mainly because they

Which of the following statements describes a cell that is considered to be differentiated?

Which of the following molecules are involved in pattern formation during development?

How does the transcription of structural genes in an inducible operon occur?

Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?

Which of the following processes destroys RNA molecules in a cell if they have a sequence complementary to an introduced double-stranded RNA?

What essential information does the product of the bicoid gene in Drosophila provide during development?

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

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

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

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