Q: If a cell contains 5 linked nucleosomes, how many base pairs of DNA are wrapped around the histone cores in total?

$$146 \times 5 = 730$$ base pairs

Question 1

Which of the following best describes the primary function of histone proteins in eukaryotic cells?

Accepted Answer

They package and organize DNA by forming nucleosomes, allowing efficient compaction within the nucleus.

Question 2

A nucleosome consists of which of the following components?

Accepted Answer

An octamer of histones (H2A, H2B, H3, H4) wrapped by approximately 146 base pairs of DNA.

Question 3

Which histone protein is responsible for binding to linker DNA and stabilizing the structure between nucleosomes?

Accepted Answer

H1

Question 4

If a genetic mutation causes the absence of histone H4 in a cell, what is the most likely consequence for chromatin structure?

Accepted Answer

Nucleosome formation will be disrupted, resulting in unstable chromatin and impaired chromosome organization.

Question 5

Which of the following equations correctly represents the total number of base pairs wrapped around $$n$$ nucleosomes, assuming each nucleosome core contains 146 base pairs?

Accepted Answer

$$146 	imes n$$

Question 6

During metaphase, chromosomes are highly condensed. Which structural feature is most responsible for this high level of compaction?

Accepted Answer

Coiling of nucleosomes into a 30 nm solenoid fiber and further folding into loop domains.

Question 7

Which statement best distinguishes bacterial genome organization from eukaryotic genome organization?

Accepted Answer

Bacterial genomes are double-stranded circular DNA located in the nucleoid, while eukaryotic genomes are linear DNA packaged into chromosomes within the nucleus.

Question 8

A scientist observes that a certain virus has a genome consisting of double-stranded DNA that is 17 meters long, yet the viral head is much smaller. What mechanism allows this DNA to fit inside the viral head?

Accepted Answer

The DNA is tightly coiled and condensed using viral proteins.

Question 9

Which of the following best explains why histones are rich in positively charged amino acids?

Accepted Answer

To interact with and neutralize the negatively charged phosphate backbone of DNA.

Question 10

A patient is diagnosed with a genetic disorder that results in unstable nucleosomes and impaired chromosome segregation during cell division. Which histone(s) are most likely affected?

Accepted Answer

Core histones (H2A, H2B, H3, H4)

Question 11

Which of the following best describes euchromatin compared to heterochromatin?

Accepted Answer

Euchromatin is less condensed and generally transcriptionally active.

Question 12

If a cell contains 5 linked nucleosomes, how many base pairs of DNA are wrapped around the histone cores in total?

Accepted Answer

$$146 	imes 5 = 730$$ base pairs

Question 13

Which of the following is NOT a function of the nuclear scaffold in eukaryotic cells?

Accepted Answer

Directly catalyzing DNA replication.

Question 14

Which of the following statements about the solenoid model of chromatin structure is correct?

Accepted Answer

It describes nucleosomes arranged in a zig-zag pattern forming a 30 nm fiber.

Question 15

Which equation would you use to calculate the total DNA length ($$L) in $$meters, given the number of base pairs ($$n) $$and the average length per base pair ($$l) in $$meters?

Accepted Answer

$$L = n 	imes l$$

Question 16

Which of the following best describes the difference between chromatin and chromosomes?

Accepted Answer

Chromatin refers to DNA and associated proteins in a less condensed state, while chromosomes are highly condensed structures formed during cell division.

Question 17

Which of the following is a correct statement about the organization of viral genomes?

Accepted Answer

Viral genomes can be double-stranded DNA or RNA and are highly condensed to fit inside the viral capsid.

Question 18

A mutation causes a cell to produce three H2B, two H3, one H4, and three H1 histones. Is there enough histones to form a nucleosome core octamer?

Accepted Answer

No, because a nucleosome core requires two copies each of H2A, H2B, H3, and H4.

Genome Organization: From Nucleotides to Chromosomes

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