Question 1

Which of the following correctly describes the difference between the sugars found in DNA and RNA nucleotides?

Accepted Answer

DNA contains 2'-deoxyribose, while RNA contains D-ribose.

Question 2

Which base is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 3

What is the correct name for a nucleotide composed of adenine, ribose, and one phosphate group?

Accepted Answer

Adenosine monophosphate (AMP)

Question 4

Which of the following is the correct sequence of numbering for the carbons in the sugar of a nucleoside?

Accepted Answer

1' to 5' (prime numbers)

Question 5

Which of the following correctly describes a phosphodiester linkage in nucleic acids?

Accepted Answer

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

Question 6

Given the following DNA sequence: 5'-ATTCGGCATGACG-3', what is the complementary sequence?

Accepted Answer

3'-TAAGCCGTAC TGC-5'

Question 7

Which of the following is NOT a pyrimidine base found in nucleic acids?

Accepted Answer

Adenine

Question 8

Why are the negatively charged phosphate groups able to stabilize the DNA double helix?

Accepted Answer

They interact with water and cations, reducing repulsion and stabilizing the helix.

Question 9

Which of the following statements about Watson-Crick base pairing is correct?

Accepted Answer

A pairs with T and G pairs with C.

Question 10

Which of the following is a reason why DNA is usually double-stranded while RNA is single-stranded?

Accepted Answer

The sequence of DNA determines its rigid helical structure, while RNA can fold into complex shapes due to its single-stranded nature.

Question 11

Which of the following is the correct chemical formula for a pentose monosaccharide?

Accepted Answer

$$C_5H_{10}O_5$

Question 12

Which of the following is true about the tautomeric forms of cytosine in RNA?

Accepted Answer

Cytosine can exist in three tautomeric forms due to different positions of hydrogens and double bonds.

Question 13

Which of the following is a feature that distinguishes RNA from DNA in a nucleotide structure?

Accepted Answer

RNA contains a 2'-hydroxyl group on the sugar, while DNA does not.

Question 14

Which of the following best explains why phosphodiester bonds in RNA are less stable than those in DNA under alkaline conditions?

Accepted Answer

RNA has a 2'-hydroxyl group that can act as a nucleophile, promoting hydrolysis of the phosphodiester bond.

Question 15

Which of the following is the correct pKa value for the second dissociation of phosphoric acid ($$H_2PO_4^-) at $$physiological pH?

Accepted Answer

$$pK_2 = 7.20$

Question 16

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

Accepted Answer

Adenine

Question 17

What is the main reason that A-G or C-T base pairs do not usually occur in double-stranded DNA?

Accepted Answer

They are both purines or both pyrimidines, causing steric clashes or insufficient hydrogen bonding.

Question 18

Which of the following best describes the antiparallel nature of DNA double helix strands?

Accepted Answer

One strand runs 5' to 3' and the other runs 3' to 5'.

Question 19

Which of the following is a force that contributes to the stability of double-stranded DNA besides base-pairing?

Accepted Answer

Hydrophobic stacking interactions between bases

Biochem chapter 8: Nucleic Acids

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