Question 1

Which of the following correctly describes the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleoside consists of a base and a sugar, while a nucleotide includes a base, sugar, and phosphate group.

Question 2

Which of the following bases is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 3

What is the chemical difference between the sugars in DNA and RNA?

Accepted Answer

DNA contains deoxyribose lacking the 2'-OH group, while RNA contains ribose with a 2'-OH group.

Question 4

During DNA polymerization, nucleotides are added to which end of the growing DNA strand?

Accepted Answer

3' end

Question 5

Which of the following best explains why DNA with a high G:C content is harder to denature than DNA with a high A:T content?

Accepted Answer

G:C pairs have more hydrogen bonds (3) than A:T pairs (2), requiring more energy to break.

Question 6

Which of the following is the correct Watson and Crick model feature of DNA?

Accepted Answer

DNA is a double helix with antiparallel strands and bases paired by hydrogen bonds.

Question 7

If a DNA molecule has the following sequence on the sense strand: 5'-ATGCCGTA-3', what is the sequence of the antisense strand?

Accepted Answer

3'-TACGGCAT-5'

Question 8

Which of the following statements about the backbone of DNA is correct?

Accepted Answer

The backbone is composed of alternating sugars and phosphate groups.

Question 9

Which of the following best describes the directionality of DNA strands?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5', making them antiparallel.

Question 10

Which of the following is a purine base found in nucleic acids?

Accepted Answer

Adenine

Question 11

A scientist is designing a probe to detect a specific DNA sequence in a crime scene sample. Which property of DNA is most critical for the probe to work?

Accepted Answer

The ability of DNA bases to pair specifically via hydrogen bonds (complementary base pairing).

Question 12

Which of the following equations correctly represents the formation of a phosphodiester bond during DNA polymerization?

Accepted Answer

$$\mathrm{(dNMP)} + \mathrm{(dNTP)} \rightarrow \mathrm{(DNA)} + \mathrm{PP_i}$$

Question 13

Which of the following would most likely result in the denaturation of double-stranded DNA in a laboratory setting?

Accepted Answer

Adding formamide or dimethyl sulfoxide.

Question 14

Which of the following statements about sense and antisense DNA strands is correct?

Accepted Answer

The antisense strand is used as a template for RNA synthesis.

Question 15

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

Accepted Answer

Amino acid

Question 16

A mutation changes a cytosine base to a thymine base in a DNA molecule. Which type of base pairing is affected?

Accepted Answer

A pyrimidine-purine pairing is altered, changing from C-G (3 H bonds) to T-A (2 H bonds).

Question 17

Which of the following best describes the major groove in the DNA double helix?

Accepted Answer

It is wider and more accessible to proteins for binding and recognition.

Question 18

Which of the following statements about the function of DNA and RNA is correct?

Accepted Answer

DNA serves as a permanent template for genetic information, while RNA acts as a temporary copy that can perform various functions.

Question 19

Which of the following is a real-world application of DNA base-pairing?

Accepted Answer

Using antisense probes to detect specific DNA sequences in forensic analysis.

DNA & RNA Structure: Foundations of Molecular Biology

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