Question 1

Which of the following is NOT a component of a nucleotide as shown in the provided study materials?

Accepted Answer

A carboxylic acid group

Question 2

What is the main structural difference between DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil

Question 3

Which of the following best describes the linkage between two nucleotides in a polynucleotide chain?

Accepted Answer

A phosphodiester bond between the 3' hydroxyl of one sugar and the 5' phosphate of the next

Question 4

Which of the following is a correct abbreviation for a deoxyribonucleotide triphosphate containing cytosine?

Accepted Answer

dCTP

Question 5

Which of the following statements about the double helix structure of DNA is TRUE?

Accepted Answer

The two strands are antiparallel and the bases are perpendicular to the backbone

Question 6

Which of the following base pairs is stabilized by three hydrogen bonds?

Accepted Answer

Guanine–Cytosine

Question 7

Which of the following is a function of nucleotides in the cell, besides being building blocks of nucleic acids?

Accepted Answer

They act as cofactors in metabolic reactions (e.g., NAD+, FAD)

Question 8

A sample of double-stranded DNA is found to contain 20% adenine. According to Chargaff’s rules, what percentage of guanine does it contain?

Accepted Answer

30%

Question 9

Which of the following best explains why histone proteins are rich in lysine and arginine?

Accepted Answer

They are positively charged and form salt bridges with the negatively charged DNA backbone

Question 10

Which of the following is the most compact form of DNA organization in the cell?

Accepted Answer

Chromosome

Question 11

A mutation causes cytosine to be deaminated to uracil in DNA. If this mutation is not repaired before replication, what is the likely outcome after two rounds of DNA replication?

Accepted Answer

One daughter DNA molecule will have a T-A base pair where the original was C-G

Question 12

Which of the following best describes semiconservative replication?

Accepted Answer

Each new DNA double helix contains one old and one new strand

Question 13

Which of the following is the correct reverse complement of the DNA sequence 5’ TTT CAG GTG CAT 3’?

Accepted Answer

ATG CAC CTG AAA

Question 14

Which of the following cofactors does NOT contain a nucleotide?

Accepted Answer

TPP

Question 15

Which amino acid would you expect to find in high amounts on DNA-binding histone proteins, in addition to lysine and arginine?

Accepted Answer

Histidine

Question 16

Which of the following interactions provides the greatest stabilizing force for the double-helix structure of DNA?

Accepted Answer

Dispersion (stacking) forces between aromatic bases

Question 17

A protein binds DNA using a specific binding pocket on the protein surface. Which amino acid residue would you expect to find there?

Accepted Answer

Lysine

Question 18

Which of the following best describes the directionality of a polynucleotide chain?

Accepted Answer

It is always written from the 5’ end to the 3’ end

Question 19

Which of the following represents a possible composition of double-stranded DNA according to Chargaff’s rules?

Accepted Answer

15% A, 35% G, 35% C, 15% T

Question 20

Which of the following best describes the role of hydrogen bonding in DNA base pairing?

Accepted Answer

It determines the specificity of base pairing between A-T and G-C

Nucleic Acid Structure: DNA, RNA, and Their Biological Functions

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