Even though the lac Z , Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.

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Answer 1

Textbook Question

Chapter 16, Problem 1NST

Even though the lac Z, Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

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Answer i

Answer

Answer 2

Textbook Question

Chapter 16, Problem 1NST

Even though the lac Z, Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

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Answer 3

Textbook Question

Chapter 16, Problem 1NST

Even though the lac Z, Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

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Answer 4

Textbook Question

Chapter 16, Problem 1NST

Even though the lac Z, Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

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Answer 5

Textbook Question

Answer 6

Textbook Question

Answer 7

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

Answer 8

(a)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

Answer 9

(a)

Expert Solution

Answer 10

(a)

Expert Solution

Answer 11

Expert Solution

Answer 12

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides presents early in the Z gene.

Introduction: The lac operon contains its promoter, regulator, and three structural genes designated as Z, Y, and A. The Z gene encodes β-galactosidase aids in cleaving the disaccharide lactose into its monomers glucose and galactose.

Answer 13

Explanation of Solution

If there is a deletion of one nucleotide in the early Z gene, then there will be a frameshift of all the reading frames present downstream from the deletion, which alters many amino acids. As a result of mutation, either premature chain termination of the translation will occur, or the normal chain termination will be ignored. If such a cell is placed in a lactose medium, it will be incapable of growing because of the unavailability of the β-galactosidase gene.

Thus, the cell with a deletion mutation in the early Z gene is incapable of growing in lactose medium because of the absence of the β-galactosidase gene.

Answer 14

(b)

Expert Solution

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

Answer 15

(b)

Expert Solution

Answer 16

(b)

Expert Solution

Answer 17

Expert Solution

Answer 18

Summary Introduction

To determine: The fate of a cell growing in the presence of lactose and containing a deletion in one of the nucleotides present early in the A gene

Introduction: The lac operon contains three structural genes known as lacZ, lacY, and lacA. The three genes are transcribed in the form of a single mRNA under the control of one lac promoter. The lacA codes for transacetylase that transfer acetyl groups from acetyl-coenzyme A to β-galactoside.

Answer 19

Explanation of Solution

When there is a deletion of one nucleotide in the early A gene, the expected function of A gene product is impaired, but the use of lactose as a carbon source is not influenced. In this situation, if a cell is placed in a lactose-containing medium, then the cell will grow normally.

Thus, the cell with a deletion mutation in the early A gene has impaired gene A product, and it can grow normally in the lactose-containing medium.

Answer 20

Ch. 16 - Even though the lac Z, Y, and A structural genes...Ch. 16 - Predict the level of genetic activity of the lac...Ch. 16 - Prob. 1CS Ch. 16 - Prob. 2CS Ch. 16 - Prob. 3CS Ch. 16 - HOW DO WE KNOW? In this chapter, we focused on the...Ch. 16 - Prob. 2PDQ Ch. 16 - Contrast positive versus negative control of gene...Ch. 16 - Contrast the role of the repressor in an inducible...Ch. 16 - For the lac genotypes shown in the following...

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