Question 1

Which of the following best describes the chemical difference between the sugars in DNA and RNA?

Accepted Answer

DNA contains deoxyribose, which lacks a hydroxyl group at the 2' carbon, while RNA contains ribose, which has a hydroxyl group at the 2' carbon.

Question 2

Which of the following base pairs is stabilized by three hydrogen bonds in the DNA double helix?

Accepted Answer

Guanine–Cytosine

Question 3

What is the primary function of histone proteins in eukaryotic chromosomes?

Accepted Answer

To package DNA into nucleosomes and regulate gene accessibility

Question 4

Which of the following statements about the antiparallel nature of DNA is correct?

Accepted Answer

One DNA strand runs 5' to 3', and the complementary strand runs 3' to 5'.

Question 5

A segment of DNA has the sequence 5'-AAGTCCGGGTACGCTA-3'. What is the sequence of the complementary strand?

Accepted Answer

3'-TTCAGGCCCATGCGAT-5'

Question 6

Which of the following is NOT a component of a nucleotide?

Accepted Answer

A fatty acid tail

Question 7

Which of the following best explains why DNA is more stable than RNA under cellular conditions?

Accepted Answer

DNA lacks a hydroxyl group at the 2' carbon, making it less susceptible to hydrolysis.

Question 8

Which of the following is a purine base found in both DNA and RNA?

Accepted Answer

Adenine

Question 9

What is the role of nonhistone proteins in chromatin?

Accepted Answer

They play a primary role in gene regulation and chromosome structure.

Question 10

Which of the following best describes the three levels of DNA packaging in eukaryotic chromosomes?

Accepted Answer

Nucleosome formation, solenoid fiber formation, and looped domain formation

Question 11

Which of the following is true regarding the chemical polarity of DNA?

Accepted Answer

The 5' to 3' orientation of one strand is opposite to the 3' to 5' orientation of the other strand.

Question 12

Which of the following statements about telomeres is correct?

Accepted Answer

Telomeres are found at the ends of eukaryotic chromosomes and have unique properties.

Question 13

Which of the following best explains why supercoiling of DNA is important in cells?

Accepted Answer

It allows the large DNA molecules to fit within the limited space of the cell nucleus.

Question 14

Which of the following is a pyrimidine base found only in RNA?

Accepted Answer

Uracil

Question 15

Which of the following statements about the structure of a nucleosome is correct?

Accepted Answer

A nucleosome consists of DNA wrapped around an octamer of histone proteins.

Question 16

Which of the following best describes the composition of a eukaryotic chromosome?

Accepted Answer

A single, giant DNA molecule complexed with proteins

Question 17

Which of the following is a correct statement about the base composition of DNA?

Accepted Answer

The concentration of adenine equals the concentration of thymine.

Question 18

Which of the following is a real-world consequence of mutations in the DNA sequence of a gene?

Accepted Answer

The protein encoded by the gene may be altered, potentially causing disease.

Question 19

Which of the following best explains the specificity of base pairing in DNA?

Accepted Answer

The size and shape of the bases allow only certain pairs to fit together, stabilized by hydrogen bonds.

Question 20

Which of the following is a function of centromeres in chromosomes?

Accepted Answer

They serve as the attachment site for spindle fibers during cell division.

DNA and the Molecular Structure of Chromosomes: Study Notes for Genetics Students

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