Question 1

In the accompanying diagram,what type of control,positive or negative,is operating?

Accepted Answer

The answer of In the accompanying diagram,what type of control,positive...

Question 2

What is an allosteric molecule?

Accepted Answer

One that can change

Question 3

Which term most appropriately refers to a regulatory protein in prokaryotes?

Accepted Answer

A)  translation 
B)  RNA processing 
C)  DNA binding protein 
D)  gyrase action 
E)  helicase activation 
A)  translation 
B)  RNA processing 
C)  DNA binding protein 
D)  gyrase action 
E)  helicase activation

Question 4

Under a system of negative control,genetic expression occurs unless such expression is shut off by some form of regulator.

Accepted Answer

A) True 
 B)False

Question 5

The accompanying table lists several genotypes associated with the lac operon in E.coli.For each,indicate with a "+" or a "-" whether β-galactosidase would be expected to be produced at induced levels.
 $\begin{array}{llcc}
&\beta \text {-galactosidase production }\
\underline {   \text { Genotype }  } &\underline {\text { No Lactose \quad \quad  With Lactose}} \
(a) \quad  I^{+} O+Z+/ F^{\prime} I+O+Z+&\
(b) \quad I-O c Z-/ F^{\prime} I-O c Z-  \
(c)\quad I{s}  I-O c Z+/ F^{\prime} I-O+Z+  \
(d) \quad Is Oc Z-/F'Is O+Z+\
\end{array}$

$\begin{array}{l}
I^{+}=\text {wild-type repressor } \
I^{-}=\text {mutant repressor (unable to bind to the operator) } \
I^{s}=\text { mutant repressor (insensitive to lactose) } \
O^{+}=\text {wild-type operator } \
O \mathcal{C}=\text { constitutive operator (insensitive to repressor) }
\end{array}$

Accepted Answer

(a) - +
(b

Question 6

Which of the following terms best characterizes catabolite repression associated with the lac operon in E.coli?

Accepted Answer

A)  inducible system 
B)  repressible system 
C)  negative control 
D)  positive control 
E)  constitutive 
A)  inducible system 
B)  repressible system 
C)  negative control 
D)  positive control 
E)  constitutive

Question 7

Explain why lacOᶜ mutations are cis-acting while lacI mutations can be trans-acting.

Accepted Answer

The operator region

Question 8

Regarding the lactose utilization system in E.coli,a gratuitous inducer is a molecule that is chemically analogous to lactose and induces the operon,but is not a substrate for the enzymes of the lac operon.

Accepted Answer

A) True 
 B)False

Question 9

In the lac operon,the product of structural gene lacZ is capable of ________.

Accepted Answer

A)  nonautonomous replication 
B)  forming lactose from two glucose molecules 
C)  replacing hexokinase in the early steps of glycolysis 
D)  splitting the -linkage of lactose 
E)  forming ATP from pyruvate 
A)  nonautonomous replication 
B)  forming lactose from two glucose molecules 
C)  replacing hexokinase in the early steps of glycolysis 
D)  splitting the -linkage of lactose 
E)  forming ATP from pyruvate

Question 10

What is the function of the lacY gene in the lac operon?

Accepted Answer

The lacY gene codes for permea

Question 11

The table below lists several genotypes associated with the lac operon in E.coli.For each,indicate with a "+" or a "-" whether functional β-galactosidase would be expected to be produced at induced levels.
 $\begin{array}{llcc}
&\beta \text {-galactosidase production }\
\underline {   \text { Genotype }  } &\underline {\text { No Lactose \quad \quad  With Lactose}} \
(a) \quad I+O+Z+/ F^{\prime} I-O+Z+ &\
(b) \quad I-O c Z+/ F^{\prime} I-O+Z- \
(c)\quad I{s}  O c Z+/ F^{\prime} I+O+Z+ \
(d) \quad  I-O+Z+/ F^{\prime} I-O+Z+ \
\end{array}$

$\begin{array}{l}
I^{+}=\text {wild-type repressor } \
I^{-}=\text {mutant repressor (unable to bind to the operator) } \
I^{s}=\text { mutant repressor (insensitive to lactose) } \
O^{+}=\text {wild-type operator } \
O \mathcal{C}=\text { constitutive operator (insensitive to repressor) }
\end{array}$

Accepted Answer

(a) - + (b

Question 12

What experimental results would indicate that the mutation lacIˢ is dominant to lacI⁺?

Accepted Answer

In lacIˢ / lacI⁺ partial diplo

Question 13

A constitutive mutation in the lac operon may be of several types.Name two types of constitutive mutations.

Accepted Answer

The answer of A constitutive mutation in the lac operon...

Question 14

The ara operon is controlled by a regulator protein that exerts ________.

Accepted Answer

A)  induction and expression 
B)  expressivity and penetrance 
C)  positive and negative control 
D)  upward and reverse control 
E)  top and bottom control 
A)  induction and expression 
B)  expressivity and penetrance 
C)  positive and negative control 
D)  upward and reverse control 
E)  top and bottom control

Question 15

What symbols are used to describe constitutive mutations at specific regions of the lac regulatory system?

Accepted Answer

The answer of What symbols are used to describe constitutive...

Question 16

The catabolite repression system in E.coli essentially represses the lac operon when glucose is present.What evolutionary advantage would favor evolution of such a system?

Accepted Answer

Glucose can enter glycolysis "as is," wh

Question 17

The lac operon consists of three structural genes as well as the adjacent region of DNA known as the regulator.

Accepted Answer

A) True 
 B)False

Question 18

Present an overview of prokaryotic regulation in terms of growth efficiency.

Accepted Answer

Genetic systems have evolved that allow

Question 19

Regarding the trp operon,trpR- maps to a considerable distance from the structural genes.The mutation either inhibits the interaction with tryptophan or inhibits repressor formation entirely.In the presence of tryptophan in the medium,would you expect the trp operon to be transcriptionally active? Explain.

Accepted Answer

With either of the two scenarios mention

Question 20

Attenuation is known to occur in the lac operon.

Accepted Answer

A) True 
 B)False

Exam 16: Regulation of Gene Expression in Prokaryotes

In the accompanying diagram,what type of control,positive or negative,is operating?

What is an allosteric molecule?

Which term most appropriately refers to a regulatory protein in prokaryotes?

Under a system of negative control,genetic expression occurs unless such expression is shut off by some form of regulator.

Which of the following terms best characterizes catabolite repression associated with the lac operon in E.coli?

Explain why lacOᶜ mutations are cis-acting while lacI mutations can be trans-acting.

Regarding the lactose utilization system in E.coli,a gratuitous inducer is a molecule that is chemically analogous to lactose and induces the operon,but is not a substrate for the enzymes of the lac operon.

In the lac operon,the product of structural gene lacZ is capable of ________.

What is the function of the lacY gene in the lac operon?

What experimental results would indicate that the mutation lacIˢ is dominant to lacI⁺?

A constitutive mutation in the lac operon may be of several types.Name two types of constitutive mutations.

The ara operon is controlled by a regulator protein that exerts ________.

What symbols are used to describe constitutive mutations at specific regions of the lac regulatory system?

The catabolite repression system in E.coli essentially represses the lac operon when glucose is present.What evolutionary advantage would favor evolution of such a system?

The lac operon consists of three structural genes as well as the adjacent region of DNA known as the regulator.

Present an overview of prokaryotic regulation in terms of growth efficiency.

Attenuation is known to occur in the lac operon.

Introduction to Genetics

Mitosis and Meiosis

Mendelian Genetics

Extensions of Mendelian Genetics

Chromosome Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Sex Determination and Sex Chromosomes

Chromosome Mutations: Variation in Number and Arrangement

Extranuclear Inheritance

DNA Structure and Analysis

DNA Replication and Recombination

DNA Organization in Chromosomes

The Genetic Code and Transcription

Translation and Proteins

Gene Mutation,dna Repair,and Transposition

Regulation of Gene Expression in Eukaryotes

Developmental Genetics

Cancer and Regulation of the Cell Cycle

Recombinant DNA Technology

Genomics, bioinformatics, and Proteomics

Applications and Ethics of Genetic Engineering and Biotechnology

Quantitative Genetics and Multifactorial Traits

Neurogenetics

Population and Evolutionary Genetics

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