Question 1

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

Accepted Answer

DNA is tightly bound to histone and nonhistone proteins, forming chromatin within the nucleus.

Question 2

What is the basic structural unit of chromatin in eukaryotic cells?

Accepted Answer

Nucleosome

Question 3

A researcher treats eukaryotic chromatin with a nuclease and observes DNA fragments at 200-bp intervals. What does this result indicate?

Accepted Answer

Nucleosomes are spaced at regular intervals along the DNA.

Question 4

Which histone is present in about half the amount of the others and is associated with linker DNA between nucleosomes?

Accepted Answer

H1

Question 5

Which of the following modifications to histone tails is most commonly associated with increased transcriptional activity?

Accepted Answer

Acetylation of lysine residues

Question 6

A cell biologist observes a region of chromatin that is highly compacted and stains darkly in electron micrographs. This region is most likely:

Accepted Answer

Heterochromatin

Question 7

Which of the following best describes the function of centromeres during cell division?

Accepted Answer

They serve as sites for kinetochore formation and spindle microtubule attachment.

Question 8

Short tandem repeats (STRs) are commonly used in DNA fingerprinting because:

Accepted Answer

They consist of short, highly variable repeat units that differ in number among individuals.

Question 9

Which of the following statements about bacterial chromosomes is correct?

Accepted Answer

Most bacteria have a single circular chromosome localized to the nucleoid.

Question 10

A scientist isolates a DNA element from the human genome that is about 7000 bp long and contains genes for its own mobilization. This element is most likely:

Accepted Answer

A LINE (long interspersed nuclear element)

Question 11

Which equation best represents the number of times DNA wraps around the histone octamer in a nucleosome core particle?

Accepted Answer

$$1.7$$

Question 12

During chromatin packing, which protein is primarily responsible for holding DNA loops together in mammals?

Accepted Answer

Cohesin

Question 13

Which of the following is true regarding mitochondrial DNA in humans?

Accepted Answer

It is circular and encodes 37 genes.

Question 14

Which type of DNA sequence accounts for the largest proportion of the human genome?

Accepted Answer

Interspersed repeated DNA (transposable elements)

Question 15

A mutation in the gene encoding histone acetyltransferase (HAT) would most likely result in:

Accepted Answer

Reduced chromatin accessibility and lower transcription rates.

Question 16

Which of the following best describes the difference between exons and introns?

Accepted Answer

Exons are coding regions that remain in mature mRNA, while introns are noncoding regions removed during RNA processing.

Question 17

Which of the following is a function of telomeres?

Accepted Answer

They protect chromosome ends from degradation during DNA replication.

Question 18

Which of the following best explains why chromatin in metabolically active cells is mostly euchromatic?

Accepted Answer

Euchromatin is loosely packed, allowing easy access for transcriptional machinery.

Question 19

Which of the following is true about plasmids in bacteria?

Accepted Answer

They are small, circular DNA molecules that replicate autonomously and may carry genes for cellular functions.

Question 20

Which of the following is a correct statement about the composition of the histone octamer in a nucleosome?

Accepted Answer

It contains two copies each of H2A, H2B, H3, and H4.

DNA Packaging and Chromosome Structure: The Structural Basis of Cellular Information

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