Question 1

Which of the following best describes the role of histone acetylation in chromatin structure and gene expression?

Accepted Answer

Histone acetylation decreases the overall positive charge of histones, allowing DNA to loosely coil and promoting gene expression.

Question 2

What is the primary function of telomeres in eukaryotic chromosomes?

Accepted Answer

To protect the ends of chromosomes from degradation and prevent loss of genetic information during DNA replication.

Question 3

During DNA replication, why is the lagging strand synthesized in fragments known as Okazaki fragments?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the 5' to 3' direction, requiring discontinuous synthesis on the lagging strand.

Question 4

Which chemical modification of histones is most commonly associated with transcriptionally inactive heterochromatin?

Accepted Answer

Histone methylation

Question 5

A cell is observed to have highly condensed chromatin that is inaccessible to RNA polymerase. Which term best describes this chromatin state?

Accepted Answer

Heterochromatin

Question 6

Which of the following equations correctly represents the directionality of DNA polymerase activity during replication?

Accepted Answer

$$5' \rightarrow 3'$$

Question 7

If a human cell undergoes mitosis, how many chromosomes will each daughter cell contain?

Accepted Answer

46 chromosomes

Question 8

Which of the following best explains why telomerase is important in stem cells and cancer cells?

Accepted Answer

Telomerase extends telomeres, allowing cells to divide many times without losing essential genetic information.

Question 9

Which of the following is NOT a component of the nucleosome core particle?

Accepted Answer

Histone H1

Question 10

A mutation causes a cell to lose the ability to acetylate histones. What is the most likely consequence for gene expression?

Accepted Answer

Gene expression will decrease due to tighter chromatin structure.

Question 11

Which of the following sequences is found at the ends of human chromosomes and is repeated approximately 2500 times?

Accepted Answer

$$TTAGGG$$

Question 12

Which process is directly responsible for the formation of euchromatin from heterochromatin?

Accepted Answer

Histone acetylation

Question 13

In eukaryotic cells, what is the function of the histone H1 protein?

Accepted Answer

It binds to the linker DNA between nucleosomes, helping to further compact chromatin.

Question 14

Which of the following best describes the difference between homologous chromosomes and sister chromatids?

Accepted Answer

Homologous chromosomes are pairs inherited from each parent, while sister chromatids are identical copies formed during DNA replication.

Question 15

Which of the following statements about DNA methylation is correct?

Accepted Answer

DNA methylation generally decreases gene expression.

Question 16

A researcher observes that a cell has a high level of histone methylation and low levels of gene expression. Which chromatin state is most likely present?

Accepted Answer

Heterochromatin

Question 17

Which of the following best explains why the ends of the lagging strand cannot be fully replicated by DNA polymerase?

Accepted Answer

The final RNA primer cannot be laid at the very end of the lagging strand, leaving a short segment unreplicated.

Question 18

Which of the following is a direct consequence of telomere shortening in somatic cells?

Accepted Answer

Cellular aging and eventual loss of replicative ability.

Question 19

Which of the following best describes the packaging hierarchy of DNA in eukaryotic cells?

Accepted Answer

DNA double helix $$\rightarrow$$ nucleosome $$\rightarrow$$ chromatin fiber $$\rightarrow$$ chromosome

Question 20

Which of the following is a plausible outcome if a cell loses the ability to methylate histones?

Accepted Answer

Chromatin will remain in a more open, euchromatin state, potentially increasing gene expression.

DNA Condensation into Chromosomes: Mechanisms and Biological Significance

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