The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that (1) cannot bind to DNA, (2) cannot bind tryptophan, or (3) binds to DNA even in the absence of tryptophan Introduction: The tryptophan ( trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

Question

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Answer 1

Question

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

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Answer 2

Question

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

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Answer 3

Question

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

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Answer 4

Question

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

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Answer 5

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

Answer 6

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

Answer 7

Chapter 8, Problem 1Q

A.

Summary Introduction

To determine: The effect on regulation of tryptophan operon in cells that express a mutant form of tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

Answer 8

A.

Expert Solution

Explanation of Solution

The tryptophan repressor is required to stop the transcription of genes coding for enzymes required for tryptophan synthesis. If the repressor in tryptophan operon is mutated, it would be no longer regulated by the presence or absence of tryptophan. In the case of scenarios (1) and (2) where the repressor is unable to bind to DNA and tryptophan, respectively, the operon would be permanently on in these two scenarios, and the enzymes would continue to synthesize tryptophan. However, in scenario (3), the operon would be permanently shut off, as the repressor would remain occupied by the mutant repressor.

Answer 9

A.

Expert Solution

Answer 10

A.

Expert Solution

Answer 11

Expert Solution

Answer 12

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.

Answer 13

B.

Summary Introduction

To determine: The effect on scenarios (1), (2), and (3) if cells produced normal tryptophan repressor from the second, normal gene.

Introduction: The tryptophan (trp) operon is a repressible operon and controls the synthesis of tryptophan amino acid. This operon is usually ‘ON’ and the repressor is inactive. The RNA polymerase enzyme binds to the promoter region in the operon and transcribes the genes, resulting in the production of tryptophan. This operon is repressed when tryptophan is accumulated in large amounts. This is because tryptophan itself acts as a corepressor and activates the repressor protein by binding to it. This active trp repressor binds to the operator and inhibits transcription of the genes encoding enzymes required for tryptophan synthesis.

Answer 14

B.

Expert Solution

Explanation of Solution

If a normal tryptophan repressor is produced in cells from a normal gene, then gene regulation would be restored to normal in scenarios (1) and (2). The genes encoding the enzymes for the synthesis of tryptophan would be regulated. There will be no effect in scenario (3) as in that case, the repressor binds to DNA even in the absence of tryptophan. The operator would be fully bound by the mutant repressor even if tryptophan is present resulting in permanent shutting down of tryptophan operon.