Although histone modifications can activate or silence genes, these covalent alterations are made to protein molecules involved in nucleosome structure and not to the DNA carrying the activated or silenced allele. If the fixed pattern of active and silenced alleles is to be carried through multiple cell divisions, would you expect the histone modifications to be in cis or trans to the affected alleles? Why? Hint: This problem involves an understanding of how many copies of each histone are contained in a nucleosome and of the spatial relationship between the histones and the DNA wound around the nucleosome.

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Answer 1

Textbook Question

Chapter 19, Problem 1NST

Although histone modifications can activate or silence genes, these covalent alterations are made to protein molecules involved in nucleosome structure and not to the DNA carrying the activated or silenced allele. If the fixed pattern of active and silenced alleles is to be carried through multiple cell divisions, would you expect the histone modifications to be in cis or trans to the affected alleles? Why?

Hint: This problem involves an understanding of how many copies of each histone are contained in a nucleosome and of the spatial relationship between the histones and the DNA wound around the nucleosome.

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

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Students have asked these similar questions

In eukaryotic cells, the nucleosomal core contains which arrangement of histone proteins? A. two H1, one H2A, one H2B, two H3, and two H4 histone proteins B. two H2B, two H2A, two H3, and two H1 histone proteins C. two H3, two H1, two H2A, and two H2B histone proteins D. two H4, two H3, two H2B, and two H2A histone proteins E. two H2A, two H3, two H4, and two H1 histone proteins

In eukaryotes which of the following combination of chromatin conditions would be most likely to result in the highest levels of expression of gene?

An old genetic observation is that a normally active gene will be silenced if it is moved by transposition or crossing over from an uncondensed (euchromatic) region to a heavily condensed (heterochromatic) region of a chromosome. Assume the euchromatic chromatin containing the active gene is surrounded by heterochromatic chromatin immediately after insertion. Please explain in terms of the control of histone modification why the normally active gene is silenced when it becomes surrounded by condensed regions. (Do not explain how histone modification causes chromatin condensation.)

Answer 2

Textbook Question

Chapter 19, Problem 1NST

Although histone modifications can activate or silence genes, these covalent alterations are made to protein molecules involved in nucleosome structure and not to the DNA carrying the activated or silenced allele. If the fixed pattern of active and silenced alleles is to be carried through multiple cell divisions, would you expect the histone modifications to be in cis or trans to the affected alleles? Why?

Hint: This problem involves an understanding of how many copies of each histone are contained in a nucleosome and of the spatial relationship between the histones and the DNA wound around the nucleosome.

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

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Answer 3

Textbook Question

Chapter 19, Problem 1NST

Although histone modifications can activate or silence genes, these covalent alterations are made to protein molecules involved in nucleosome structure and not to the DNA carrying the activated or silenced allele. If the fixed pattern of active and silenced alleles is to be carried through multiple cell divisions, would you expect the histone modifications to be in cis or trans to the affected alleles? Why?

Hint: This problem involves an understanding of how many copies of each histone are contained in a nucleosome and of the spatial relationship between the histones and the DNA wound around the nucleosome.

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

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Answer 4

Textbook Question

Chapter 19, Problem 1NST

Although histone modifications can activate or silence genes, these covalent alterations are made to protein molecules involved in nucleosome structure and not to the DNA carrying the activated or silenced allele. If the fixed pattern of active and silenced alleles is to be carried through multiple cell divisions, would you expect the histone modifications to be in cis or trans to the affected alleles? Why?

Hint: This problem involves an understanding of how many copies of each histone are contained in a nucleosome and of the spatial relationship between the histones and the DNA wound around the nucleosome.

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

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Answer 5

Textbook Question

Answer 6

Textbook Question

Answer 7

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

Answer 8

Expert Solution & Answer

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.

Conclusion

The gene in the chromatin will have to be in a cis state to carry the histone modifications under multiple cell divisions.

Answer 9

Expert Solution & Answer

Answer 10

Expert Solution & Answer

Answer 11

Summary Introduction

To determine: The presence of cis or trans histone modifications in the affected alleles in several cell divisions.

Introduction: The mutation is the change in the nucleotide sequence of the gene, which result in either the formation of a defective protein or no protein at all. The mutation can also alter the regulation of certain genes leading to their hyperactivity or hypoactivity.

Answer 12

Explanation of Solution

The activation of the gene can only take place when the chromatin that contains the gene and its respective regulatory regions to be present in the “open state.” Similarly, for the silencing of the gene, the chromatin containing the gene and its regulatory regions need to be present in a closed state. When these chromatin structures undergo and persist through several cell divisions, the histones that are present in the immediate proximity of the gene, that is cis state will be carrying the histone modifications.