Q: Which equation correctly represents the number of telomere repeats in a human chromosome, given that each telomere contains about 2500 repeats and there are two telomeres per chromosome?

$\text{Total repeats per chromosome} = 2500 \times 2$

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 positive charge of histones, loosening DNA coiling and promoting gene expression.

Question 2

A researcher observes that a region of chromatin is highly methylated and transcriptionally inactive. What is the most likely form of this chromatin?

Accepted Answer

Heterochromatin

Question 3

Which of the following is the correct order of DNA packaging from least to most condensed?

Accepted Answer

DNA double-helix → nucleosome → euchromatin → heterochromatin → metaphase chromosome

Question 4

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

Accepted Answer

RNA primers cannot be laid at the exact end of the lagging strand, so synthesis occurs in Okazaki fragments.

Question 5

What is the function of telomerase in highly replicative cells?

Accepted Answer

Telomerase adds repetitive sequences to telomeres, allowing cells to replicate DNA without losing genetic information.

Question 6

Which histone proteins are found in the nucleosome core particle?

Accepted Answer

H2A, H2B, H3, H4

Question 7

A mutation causes the loss of histone H1 in a cell. What is the most likely consequence?

Accepted Answer

Chromatin will be less compact, leading to increased gene expression.

Question 8

Which chemical modification is most associated with transcriptional repression in chromatin?

Accepted Answer

DNA methylation

Question 9

If a cell has 46 chromosomes, how many pairs of homologous chromosomes does it contain?

Accepted Answer

23

Question 10

Which equation correctly represents the number of telomere repeats in a human chromosome, given that each telomere contains about 2500 repeats and there are two telomeres per chromosome?

Accepted Answer

$	ext{Total repeats per chromosome} = 2500 	imes 2$

Question 11

Which of the following statements about euchromatin is correct?

Accepted Answer

Euchromatin is loosely packed and accessible to polymerases, allowing gene expression.

Question 12

A cell is observed to have increased histone methylation at a gene promoter. What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease due to chromatin condensation.

Question 13

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

Accepted Answer

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

Question 14

Which of the following is a direct consequence of chromatin condensation into heterochromatin?

Accepted Answer

Transcriptional inactivity due to inaccessibility to polymerases

Question 15

Which process is most likely to occur if a cell's telomerase is abnormally activated?

Accepted Answer

Continuous cell division due to maintenance of telomere length

Question 16

Which of the following best describes the composition of a nucleosome?

Accepted Answer

A nucleosome consists of DNA wrapped around a core of eight histone proteins.

Question 17

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

Accepted Answer

$5' \rightarrow 3'$

Question 18

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

Accepted Answer

Chromatin will become more condensed, and gene expression will decrease.

Question 19

Which of the following is a key difference between prokaryotic and eukaryotic chromosomes?

Accepted Answer

Prokaryotes have a single circular chromosome, while eukaryotes have multiple linear chromosomes.

DNA Condensation into Chromosomes: Mechanisms and Biological Significance

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