Chapter 16, Problem 1P

For each of the terms in the left column, choose the best matching phrase in the right column.

a. induction	1. glucose prevents expression of catabolic operons
b. repressor	2. protein or RNA undergoes a reversible conformational change
c. operator	3. regulates translation of mRNAs in trans
d. allostery	4. RNA leader that regulates gene expression in response to a small molecule or ion
e. operon	5. site to which repressor binds
f. catabolite	6. termination of transcription elongation in repression response to translation
g. reporter gene	7. group of genes transcribed into one mRNA
h. attenuation	8. negative regulator
i. sRNA	9. a fusion of the regulatory region of one gene to the coding region of another gene whose product is assayed readily
j. riboswitch	10. stimulation of protein synthesis by a specific molecule

Summary Introduction

1.

To determine:

The term that describes “glucose prevents expression of catabolic operons.”

Answer to Problem 1P

Correct answer:

glucose prevents expression of catabolic operons: catabolite repression.

Explanation of Solution

Catabolite repression is seen among microbes when both glucose and lactose are supplied in their growing environment. The presence of glucose suppresses the utilization of lactose.

Summary Introduction

2.

To determine:

The term that describes “protein or RNA undergoes a reversible conformational change.”

Answer to Problem 1P

Correct answer:

Protein or RNA undergoes a reversible conformational change: allostery.

Explanation of Solution

Allostery means change in the conformation that is associated with the proteins involved in the regulation of a particular gene. The repressor molecule undergoes conformational change, which enables it to be relieved from the operator region and then promote transcription.

Summary Introduction

3.

To determine:

The term that describes “regulates transcription of mRNA in trans.”

Answer to Problem 1P

Correct answer:

Regulates translation of mRNA in trans: sRNA

Explanation of Solution

sRNA, known as short ribo nucleic acid sequence are trans-acting molecules that regulate the expression of specific genes. When a sRNA molecule binds to the mRNA, it leads to the breakdown of transcribed mRNA molecule by the action of ribonuclease enzyme. The binding of sRNA to the mRNA molecule prevents the formation of stem and loops in the mRNA.

Summary Introduction

4.

To determine:

The term that describes “RNA leader that regulates gene expression in response to a small molecule or ion.”

Answer to Problem 1P

Correct answer:

RNA leader that regulates gene expression in response to a small molecule or ion: riboswitch.

Explanation of Solution

Riboswitch is an important part of RNA leader sequence that binds to specific molecules called effectors. The formation of stem and loop in the transcript of mRNA molecule plays an important role in the continuation and attenuation of transcription through the riboswitches.

Summary Introduction

5.

To determine:

The term that describes “site to which repressor binds.”

Answer to Problem 1P

Correct answer:

Site to which repressor binds: operator.

Explanation of Solution

Operator is considered as the important part of the regulatory sequence of the gene. The repressor binds to the operator region of the regulatory gene and suppresses the process of transcription.

Summary Introduction

6.

To determine:

The term that describes “termination of transcription elongation in repression response to translation.”

Answer to Problem 1P

Correct answer:

Termination of transcription elongation in repression response to translation: attenuation.

Explanation of Solution

Attenuation is a process that controls the regulation of anabolic pathways. When the substrate is available, the transcription continues further and transcribes the functional regions or shrugs off the mRNA completely.

Summary Introduction

7.

To determine:

The term that describes “group of genes transcribed into one mRNA.”

Answer to Problem 1P

Correct answer:

Group of genes transcribed into one mRNA: operon.

Explanation of Solution

An operon is the set region found in the genome that consists of regulatory, structural, and functional portion. The structural region contains the promoter and operator whereas the functional region codes for the actual protein.

Summary Introduction

8.

To determine:

The term that describes “negative regulator.”

Answer to Problem 1P

Correct answer:

Negative regulator: repressor.

Explanation of Solution

Repressor is a type of protein molecule which prevents the transcription of the particular gene associated with the regulatory parts of the gene.

Summary Introduction

9.

To determine:

The term that describes “a fusion of the regulatory region of one gene to the coding region of another gene whose product is assayed readily.”

Answer to Problem 1P

Correct answer:

A fusion of the regulatory region of one gene to the coding region of another gene whose product is assayed readily: reporter gene.

Explanation of Solution

The function of reporter genes is monitored through the regulatory regions of other well studied genes. Due to this reason, the regulatory region of the lactose operon is used in the expression system for analyzing and studying the expression of unknown genes.

Summary Introduction

10.

To determine:

The term that describes “stimulation of protein synthesis by a specific molecule.”

Answer to Problem 1P

Correct answer:

Stimulation of protein synthesis by a specific molecule: induction.

Explanation of Solution

Induction is associated with the stimulation of protein synthesis by the process of transcription, where specific factor initiates the process of transcription.