Question 1

Which of the following best describes the difference between intragenic and second-site (extragenic) reversion mutations?

Accepted Answer

Intragenic reversion restores the reading frame by a second mutation within the same gene, while second-site reversion involves a compensatory mutation in a different gene.

Question 2

If the human genome is approximately 2 meters long and the nucleus is about 20 microns in diameter, by what factor must the DNA be compacted to fit inside the nucleus?

Accepted Answer

$$100,000$$ times

Question 3

Which of the following statements about histone proteins is TRUE?

Accepted Answer

Histones are positively charged, which allows them to interact with negatively charged DNA.

Question 4

Which histone protein is NOT part of the nucleosome core particle?

Accepted Answer

H1

Question 5

Which of the following best explains why DNA compaction is necessary in eukaryotic cells?

Accepted Answer

The length of DNA far exceeds the size of the nucleus, so compaction is required to fit the DNA inside the nucleus.

Question 6

Which of the following chromatin states is most associated with active gene expression?

Accepted Answer

Euchromatin

Question 7

A mutation deletes two base pairs in a gene, causing a frameshift. A second mutation in the same gene inserts two base pairs nearby. What is the most likely outcome?

Accepted Answer

The reading frame is restored, potentially allowing for a functional protein.

Question 8

Which of the following is a common effect of acetylation of histone tails?

Accepted Answer

Chromatin becomes less condensed and gene expression is activated.

Question 9

Which of the following best describes the role of DNA methylation at CpG sequences?

Accepted Answer

It typically silences gene expression.

Question 10

Which of the following is NOT a type of epigenetic modification?

Accepted Answer

Point mutation in a coding region

Question 11

A gene is located in a region of constitutive heterochromatin. What is the most likely effect on its expression?

Accepted Answer

The gene is likely to be transcriptionally silent.

Question 12

Which of the following best explains the phenomenon of position effect variegation?

Accepted Answer

Gene expression is altered when a gene is relocated near heterochromatin, leading to variable expression.

Question 13

Which of the following is TRUE regarding the composition of a typical eukaryotic chromosome?

Accepted Answer

It is composed of approximately half DNA and half protein.

Question 14

Which of the following histone modifications is most likely to be associated with gene repression?

Accepted Answer

Methylation of H3K9

Question 15

During which phase of the cell cycle is chromatin most highly condensed and visible under a light microscope?

Accepted Answer

Mitosis

Question 16

Which of the following best describes the function of histone H1?

Accepted Answer

It stabilizes the 30 nm fiber and helps compact chromatin.

Question 17

Which of the following statements about the human genome is correct?

Accepted Answer

Most of the genome does not encode proteins.

Question 18

A scientist treats cells with a drug that increases histone acetylation. What is the most likely effect on chromatin structure and gene expression?

Accepted Answer

Chromatin will become less condensed and gene expression will increase.

Question 19

Which of the following best describes the nucleosome?

Accepted Answer

A core of eight histone proteins wrapped by DNA.

Question 20

Which of the following is an example of facultative heterochromatin?

Accepted Answer

The inactivated X chromosome in female mammals.

Chromosome Structure and Epigenetic Regulation: Study Notes for Genetics

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