Question 1

Which of the following best describes the structural difference between bacterial and eukaryotic chromosomes?

Accepted Answer

Bacterial chromosomes are circular and associated with specific proteins, while eukaryotic chromosomes are linear and associated with a large number of proteins.

Question 2

If the DNA in a human chromosome averages $$1.5 	imes 10^8$ nucleotide pairs and is stretched out to about 4 cm, what is the approximate length of DNA in all 46 human chromosomes if stretched end-to-end?

Accepted Answer

$$184 	ext{ m}$$

Question 3

What is the basic unit of DNA packing in eukaryotic cells, and what is its structure?

Accepted Answer

The nucleosome, which consists of DNA wrapped around a core of eight histone proteins.

Question 4

During which phase of the cell cycle does chromatin become most condensed, forming metaphase chromosomes?

Accepted Answer

Metaphase

Question 5

Which of the following statements about heterochromatin is correct?

Accepted Answer

Heterochromatin is highly condensed and largely inaccessible to transcription machinery.

Question 6

A mutation causes histone tails to lose their ability to be chemically modified. Which process would most likely be affected?

Accepted Answer

Chromatin condensation and gene activity regulation

Question 7

Which property distinguishes euchromatin from heterochromatin?

Accepted Answer

Euchromatin is less condensed and more accessible for transcription.

Question 8

In a scenario where a cell’s chromatin remains highly condensed throughout interphase, what would be the most likely consequence?

Accepted Answer

Decreased gene expression due to reduced accessibility of DNA.

Question 9

Which of the following best explains why DNA must be packed into chromosomes?

Accepted Answer

To fit the large amount of DNA into the small space of the cell nucleus and regulate gene expression.

Question 10

Which of the following is a correct sequence of chromatin packing from least to most condensed?

Accepted Answer

Nucleosome → 10-nm fiber → Looped domains → Metaphase chromosome

Question 11

A scientist observes that certain regions of chromatin remain highly condensed even during interphase. Which regions are most likely being observed?

Accepted Answer

Centromeres and telomeres

Question 12

Which protein is primarily responsible for the initial level of DNA packing in eukaryotic cells?

Accepted Answer

Histone

Question 13

If a cell has a defect in the formation of looped domains during chromatin packing, which stage of chromosome condensation would be most affected?

Accepted Answer

Formation of metaphase chromosomes

Question 14

Which of the following best describes the role of linker DNA in chromatin structure?

Accepted Answer

Linker DNA connects nucleosomes in the 10-nm fiber.

Question 15

During mitosis, which protein helps to further condense chromatin into metaphase chromosomes?

Accepted Answer

Condensin

Question 16

Which of the following is a functional consequence of chromatin remodeling?

Accepted Answer

Altered accessibility of DNA for transcription and gene expression.

Question 17

A cell is observed to have a diffuse mass of chromatin in the nucleus under a light microscope. Which phase of the cell cycle is it most likely in?

Accepted Answer

Interphase

Question 18

Which of the following best explains why genes in euchromatin are more likely to be expressed than those in heterochromatin?

Accepted Answer

Euchromatin is less condensed, making DNA more accessible to transcription machinery.

Question 19

Which of the following would most likely occur if the nucleosome structure was disrupted in a eukaryotic cell?

Accepted Answer

DNA would become less organized and gene expression would be altered.

Chromosome Structure and DNA Packing in Eukaryotes

Study Guide - Practice Questions

Study Guide - Flashcards