Q: A scientist observes that a gene is silenced due to methylation of CpG islands in its promoter. Which equation best represents the relationship between methylation and gene expression?

$\text{Increased methylation} \rightarrow \text{Decreased gene expression}$

Question 1

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is loosely packed and contains genes being expressed, while heterochromatin is tightly packed and contains non-expressed DNA.

Question 2

A researcher treats cells with a drug that inhibits histone acetyltransferases (HATs). What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease because chromatin will become more condensed.

Question 3

Which enzyme removes acetyl groups from histone tails, leading to chromatin condensation?

Accepted Answer

Histone deacetylase (HDAC)

Question 4

A mutation in the SWI/SNF complex would most likely affect which process?

Accepted Answer

Chromatin remodeling and nucleosome repositioning

Question 5

Which of the following is a direct result of histone methylation?

Accepted Answer

Can create binding sites for additional proteins that activate or suppress transcription

Question 6

CpG islands are most commonly found in which genomic regions?

Accepted Answer

Promoter regions of genes

Question 7

Which of the following best explains the concept of the 'histone code'?

Accepted Answer

The combination of histone modifications that affect gene expression

Question 8

A female mammal has one of her X chromosomes inactivated in each cell. This process is known as:

Accepted Answer

X-inactivation

Question 9

Which of the following modifications is most likely to mark a protein for degradation?

Accepted Answer

Ubiquitination

Question 10

A gene is only expressed if it is inherited from the mother, but not from the father. This is an example of:

Accepted Answer

Genetic imprinting

Question 11

Which of the following is most likely to be found in regions of heterochromatin?

Accepted Answer

Few genes and transcriptionally silent regions

Question 12

Which of the following statements about histone variants is correct?

Accepted Answer

Histone variants are rare and often found in unique chromosomal regions such as centromeres.

Question 13

A scientist observes that a gene is silenced due to methylation of CpG islands in its promoter. Which equation best represents the relationship between methylation and gene expression?

Accepted Answer

$	ext{Increased methylation} ightarrow 	ext{Decreased gene expression}$

Question 14

Which of the following is a function of chaperone proteins?

Accepted Answer

They correctly fold polypeptide chains into functional conformations.

Question 15

Which of the following best describes the role of kinases in protein modification?

Accepted Answer

Kinases add phosphate groups to proteins.

Question 16

A mutation causes the loss of nuclear localization signal (NLS) in a protein. What is the most likely consequence?

Accepted Answer

The protein will not be transported into the nucleus.

Question 17

Which of the following is associated with open chromatin and active transcription?

Accepted Answer

Histone acetylation

Question 18

A patient has a genetic disorder caused by improper imprinting of a chromosome. Which of the following best explains the molecular basis of this disorder?

Accepted Answer

One allele is silenced due to epigenetic modifications such as DNA methylation.

Question 19

Which of the following is an example of a post-translational modification that can alter protein function?

Accepted Answer

Phosphorylation of a protein

Question 20

Which of the following terms is most closely associated with closed chromatin?

Accepted Answer

Heterochromatin

Chromatin Structure, Epigenetic Regulation, and Protein Modifications in Eukaryotes

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