Question 1

E. coli and many other bacteria of the human gut need to have fine- tuned regulation of gene expression in order to

Accepted Answer

A)  grow. 
B)  metabolize any nutrient. 
C)  evolve. 
D)  replicate their DNA. 
E)  effectively compete for space and nutrients. 
A)  grow. 
B)  metabolize any nutrient. 
C)  evolve. 
D)  replicate their DNA. 
E)  effectively compete for space and nutrients. E

Question 2

Full induction of the lac operon occurs when

Accepted Answer

A)  lactose levels are high and glucose levels are low. 
B)  lactose levels are low and glucose levels are high. 
C)  lactose levels are high and glucose levels are high. 
D)  lactose levels are low and glucose levels are low. 
A)  lactose levels are high and glucose levels are low. 
B)  lactose levels are low and glucose levels are high. 
C)  lactose levels are high and glucose levels are high. 
D)  lactose levels are low and glucose levels are low. A

Question 3

The product of the lacI gene is most like a car's

Accepted Answer

A)  parking brake. 
B)  engine. 
C)  accelerator pedal. 
D)  wheels. 
E)  steering wheel. 
A)  parking brake. 
B)  engine. 
C)  accelerator pedal. 
D)  wheels. 
E)  steering wheel. A

Question 4

CAP is said to be responsible for positive regulation of the lac operon because

Accepted Answer

A)  Extracellular glucose levels influence the ability of CAP to bind to the CAP binding site. 
B)  CAP prevents binding of the repressor to the operator. 
C)  CAP bound to the CAP binding site increases the frequency of transcription initiation. 
D)  CAP binds the CAP binding site. 
E)  CAP binds cAMP. 
A)  Extracellular glucose levels influence the ability of CAP to bind to the CAP binding site. 
B)  CAP prevents binding of the repressor to the operator. 
C)  CAP bound to the CAP binding site increases the frequency of transcription initiation. 
D)  CAP binds the CAP binding site. 
E)  CAP binds cAMP.

Question 5

Imagine that you discover a bacterial operon involved in the synthesis of vitamin B12. This operon is regulated by a repressor protein that binds to an operator sequence. Vitamin B12 is the allosteric effector of the repressor
-the molecule that binds to the repressor to affect its activity. Predict how vitamin B12 will influence repressor activity.

Accepted Answer

A)  When vitamin B12 binds to the repressor, the repressor binds to the operator. 
B)  When vitamin B12 binds to the repressor, the repressor can bind to RNA polymerase. 
C)  When vitamin B12 binds to the repressor, the repressor cannot bind to RNA polymerase. 
D)  When vitamin B12 binds to the repressor, the repressor cannot bind to the operator. 
A)  When vitamin B12 binds to the repressor, the repressor binds to the operator. 
B)  When vitamin B12 binds to the repressor, the repressor can bind to RNA polymerase. 
C)  When vitamin B12 binds to the repressor, the repressor cannot bind to RNA polymerase. 
D)  When vitamin B12 binds to the repressor, the repressor cannot bind to the operator.

Question 6

Extracellular glucose inhibits transcription of the lac operon by

Accepted Answer

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

Question 7

Use the following information when answering the corresponding questions).
The lac operon is used in countless ways for genetics research and biotechnology. One important use of the lac operon is to regulate the expression of cloned genes. In this application, some regulatory elements of the operon are fused to the cloned gene that is to be regulated. One application of such technology was reported by Cronin et al., The lac operator- repressor system is functional in the mouse, Genes and Development 15 2001):1506-17. These investigators fused a portion of the lac operon to the mouse tyrosinase gene, a gene required for pigment production. This recombinant DNA, composed of E. coli lac operon sequences and the mouse tyrosinase gene, was introduced into albino mice using techniques described in Chapter 19. Using the lac operon regulatory sequences, the investigators were able to regulate tyrosinase gene expression. In fact, they were able to convert albino white) mice into brown mice. The following questions ask you to use your knowledge of the lac operon to deduce how Cronin et al. were able to regulate tyrosinase gene expression in mice.
-Introducing the recombinant lac operon/mouse tyrosinase DNA into mice is only half of the equation for regulating tyrosinase. In addition to lac operon/mouse tyrosinase DNA, what other gene must be added to mice to regulate tyrosinase expression?

Accepted Answer

A)  the lacY gene 
B)  the lacI gene 
C)  the lac operator 
D)  the lacZ gene 
A)  the lacY gene 
B)  the lacI gene 
C)  the lac operator 
D)  the lacZ gene

Question 8

Catabolite activator protein CAP) activity is controlled by cAMP at the level.

Accepted Answer

A)  post- translational 
B)  translational 
C)  transcriptional 
A)  post- translational 
B)  translational 
C)  transcriptional

Question 9

Which of the following levels of gene expression allows the most rapid response to environmental change?

Accepted Answer

A)  translational control 
B)  transcriptional control 
C)  post- translational control 
A)  translational control 
B)  transcriptional control 
C)  post- translational control

Question 10

Imagine that you've added the same indicator used by Monod to E. coli colonies growing on a plate with glucose and no lactose. One colony is yellow and the remainders are white. This result suggests that cells of the yellow colony

Accepted Answer

A)  cannot metabolize lactose. 
B)  cannot transport lactose into the cell. 
C)  have constitutively active lacZ and lacY genes. 
D)  cannot activate either the lacZ or lacY gene. 
E)  can activate the lacY gene but cannot active the lacZ gene. 
A)  cannot metabolize lactose. 
B)  cannot transport lactose into the cell. 
C)  have constitutively active lacZ and lacY genes. 
D)  cannot activate either the lacZ or lacY gene. 
E)  can activate the lacY gene but cannot active the lacZ gene.

Question 11

A technique that can be used to identify mutant bacterial cells is called

Accepted Answer

A)  replica plating. 
B)  master plating. 
C)  indicator plating. 
D)  comparison plating. 
A)  replica plating. 
B)  master plating. 
C)  indicator plating. 
D)  comparison plating.

Question 12

What type of control is the SOS response regulon under?

Accepted Answer

A)  only positive control 
B)  feedback transcription 
C)  only negative control 
D)  feedback inhibition 
E)  both positive and negative control 
A)  only positive control 
B)  feedback transcription 
C)  only negative control 
D)  feedback inhibition 
E)  both positive and negative control

Question 13

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

Accepted Answer

A)  inducer 
B)  corepressor 
C)  promoter 
D)  ubiquitin 
E)  repressor 
A)  inducer 
B)  corepressor 
C)  promoter 
D)  ubiquitin 
E)  repressor

Question 14

The product of the lacI gene is

Accepted Answer

A)  fi- galactosidase. 
B)  an enzyme. 
C)  a transport protein embedded within the membrane. 
D)  the repressor. 
A)  fi- galactosidase. 
B)  an enzyme. 
C)  a transport protein embedded within the membrane. 
D)  the repressor.

Question 15

When arabinose is present in the environment, the arabinose operon is transcribed. What is this an example of?

Accepted Answer

A)  negative control 
B)  positive control 
C)  push forward control 
D)  reverse transcription 
E)  positive translation 
A)  negative control 
B)  positive control 
C)  push forward control 
D)  reverse transcription 
E)  positive translation

Question 16

A compound known as X- Gal is widely used in molecular genetic research. When wild- type normal) E. coli is grown on medium containing X- Gal, the bacterial colonies turn blue. In contrast, when lacZ mutants are grown on medium containing X- Gal, the bacterial colonies remain their normal white colour. What is X- Gal likely to be?

Accepted Answer

A)  a compound chemically similar to glucose 
B)  a compound chemically similar to lactose 
C)  a compound chemically similar to galactose 
D)  a compound that cannot be transported into lacZ mutants 
E)  a compound that can only be transported into lacA mutants 
A)  a compound chemically similar to glucose 
B)  a compound chemically similar to lactose 
C)  a compound chemically similar to galactose 
D)  a compound that cannot be transported into lacZ mutants 
E)  a compound that can only be transported into lacA mutants

Question 17

Negative control occurs when

Accepted Answer

A)  a regulatory protein binds to RNA polymerase and shuts down the process of transcription. 
B)  a regulatory protein binds to RNA and shuts down the process of transcription. 
C)  a regulatory protein binds to DNA and shuts down the process of transcription. 
D)  a regulatory protein binds to DNA polymerase and shuts down the process of transcription. 
A)  a regulatory protein binds to RNA polymerase and shuts down the process of transcription. 
B)  a regulatory protein binds to RNA and shuts down the process of transcription. 
C)  a regulatory protein binds to DNA and shuts down the process of transcription. 
D)  a regulatory protein binds to DNA polymerase and shuts down the process of transcription.

Question 18

If the genetically engineered albino mice were given no special treatment, how would the tyrosinase gene be expressed?

Accepted Answer

A)  It would be transcribed to a high level. 
B)  It would not be transcribed. 
C)  It would be transcribed to a moderate level. 
A)  It would be transcribed to a high level. 
B)  It would not be transcribed. 
C)  It would be transcribed to a moderate level.

Question 19

What is an inducer?

Accepted Answer

A)  A product that stimulates gene expression in a reaction. 
B)  A substrate that inhibits gene expression in a reaction. 
C)  A substrate that stimulates gene expression in a reaction. 
D)  A product that inhibits gene expression in a reaction. 
A)  A product that stimulates gene expression in a reaction. 
B)  A substrate that inhibits gene expression in a reaction. 
C)  A substrate that stimulates gene expression in a reaction. 
D)  A product that inhibits gene expression in a reaction.

Question 20

In gene expression, when does negative control occur? When

Accepted Answer

A)  lactose is transported into the cell. 
B)  a kinase adds a phosphate to DNA. 
C)  an activator is removed from DNA and shuts down transcription. 
D)  DNA is coiled too tightly for genes to be transcribed. 
E)  a repressor binds to DNA and shuts down transcription. 
A)  lactose is transported into the cell. 
B)  a kinase adds a phosphate to DNA. 
C)  an activator is removed from DNA and shuts down transcription. 
D)  DNA is coiled too tightly for genes to be transcribed. 
E)  a repressor binds to DNA and shuts down transcription.

Exam 18: Control of Gene Expression in Bacteria

E. coli and many other bacteria of the human gut need to have fine- tuned regulation of gene expression in order to

Full induction of the lac operon occurs when

The product of the lacI gene is most like a car's

CAP is said to be responsible for positive regulation of the lac operon because

Extracellular glucose inhibits transcription of the lac operon by

Catabolite activator protein CAP) activity is controlled by cAMP at the level.

Which of the following levels of gene expression allows the most rapid response to environmental change?

Imagine that you've added the same indicator used by Monod to E. coli colonies growing on a plate with glucose and no lactose. One colony is yellow and the remainders are white. This result suggests that cells of the yellow colony

A technique that can be used to identify mutant bacterial cells is called

What type of control is the SOS response regulon under?

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

The product of the lacI gene is

When arabinose is present in the environment, the arabinose operon is transcribed. What is this an example of?

Negative control occurs when

If the genetically engineered albino mice were given no special treatment, how would the tyrosinase gene be expressed?

What is an inducer?

In gene expression, when does negative control occur? When

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, Membranes, and the First Cells

Inside the Cell

Energy and Enzymes

Cellular Respiration and Fermentation

Photosynthesis

Cellcell Interactions

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, Rna Processing, and Translation

Control of Gene Expression in Eukaryotes

The Molecular Revolution: Biotechnology and Beyond

Gene Structure and Development

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, Signals, and Responses

Plant Reproduction and Development

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Animal Nervous Systems

Animal Sensory Systems

Animal Movement

Chemical Signals in Animals

Animal Reproduction and Development

The Immune System in Animals

An Introduction to Ecology

Behavioural Ecology

Population Ecology

Community Ecology

Ecosystems and Global Ecology

Biodiversity and Conservation Biology

Filters