Question 1

Which of the following best explains why viral and bacterial chromosomes must be precisely folded or packaged within the cell?

Accepted Answer

Because their chromosomes are much larger than the cell or viral head, requiring efficient packaging to fit inside.

Question 2

Which of the following statements about viral chromosomes is correct?

Accepted Answer

They can be either DNA or RNA, and may be single-stranded or double-stranded.

Question 3

Bacterial chromosomes are typically characterized by which of the following features?

Accepted Answer

They are circular, double-stranded DNA molecules with most of the sequence being coding regions.

Question 4

In bacteria, the level of DNA supercoiling is primarily regulated by which class of enzymes?

Accepted Answer

Topoisomerases

Question 5

Given a bacterial chromosome with 52,000 base pairs, calculate the linking number $$L$$ using the formula $$L = \frac{\#\ 	ext{of bp}}{10.4}.$$

Accepted Answer

$$L = 5,000$$

Question 6

Why is eukaryotic DNA complexed with histone proteins to form chromatin?

Accepted Answer

To fit a large amount of DNA into a small nucleus and keep it organized.

Question 7

Which of the following histones is known as the 'spacer' histone and is involved in higher-order chromatin structure?

Accepted Answer

H1

Question 8

Chromatin remodeling, which allows enzymes to access DNA, is most commonly accomplished by which of the following modifications?

Accepted Answer

Acetylation of lysine side chains, methylation, or phosphorylation of serine residues.

Question 9

Which of the following regions of eukaryotic chromosomes is most likely to remain permanently condensed (heterochromatic) during interphase?

Accepted Answer

Centromeres and telomeres

Question 10

A researcher is using DNA fingerprinting to identify individuals. Which type of DNA sequence is most useful for this purpose?

Accepted Answer

Variable number of tandem repeats (VNTRs) such as minisatellites and microsatellites

Question 11

Which of the following statements about SINEs (Short Interspersed Nuclear Elements) is correct?

Accepted Answer

They are short, mobile elements present in hundreds of thousands of copies, such as the Alu family.

Question 12

What is the primary function of telomeric DNA sequences in eukaryotic chromosomes?

Accepted Answer

To prevent chromosome ends from fusing and to protect them from degradation.

Question 13

Which of the following best describes the difference between polytene and lampbrush chromosomes?

Accepted Answer

Polytene chromosomes are paired homologs with many rounds of replication without separation, while lampbrush chromosomes have extended loops for active transcription during meiosis.

Question 14

A mutation in a gene encoding a topoisomerase in bacteria would most likely affect which of the following processes?

Accepted Answer

The regulation of DNA supercoiling and, consequently, gene expression.

Question 15

Which of the following is a characteristic of heterochromatin?

Accepted Answer

It remains condensed throughout interphase.

Question 16

Which of the following best explains why eukaryotic genomes contain large amounts of repetitive DNA?

Accepted Answer

Repetitive DNA includes satellite DNA, multicopy genes, and transposable elements, which play structural and regulatory roles.

Question 17

A scientist discovers a DNA sequence in the human genome that is 6400 bp long, present in up to 100,000 copies, and encodes a reverse transcriptase. This sequence is most likely:

Accepted Answer

A LINE (Long Interspersed Nuclear Element)

Question 18

Which of the following is true regarding the organization of eukaryotic chromosomes?

Accepted Answer

They contain large amounts of repetitive DNA, including satellite DNA, minisatellites, microsatellites, and transposons.

Question 19

Which of the following best describes the function of chromatin remodeling in eukaryotic cells?

Accepted Answer

It allows enzymes and regulatory proteins to access DNA by modifying histones and altering chromatin structure.

Question 20

A patient is found to have a genetic disorder caused by a nonfunctional gene that closely resembles a functional gene elsewhere in the genome. This nonfunctional gene is best described as:

Accepted Answer

A pseudogene

DNA Organization in Chromosomes: Viral, Bacterial, and Eukaryotic Systems

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