Question 1

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

Accepted Answer

A nucleotide contains a sugar, nitrogenous base, and phosphate group, while a nucleoside contains only a sugar and nitrogenous base.

Question 2

Which nitrogenous base is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 3

What type of bond connects the nitrogenous base to the sugar in nucleotides and nucleosides?

Accepted Answer

Beta-N-glycosidic bond

Question 4

Which sugar is present in DNA, and how does it differ from the sugar in RNA?

Accepted Answer

DNA contains 2'-deoxy-D-ribose, which lacks a hydroxyl group at the 2' position compared to RNA's D-ribose.

Question 5

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

Accepted Answer

Adenine

Question 6

What is the correct name for the nucleotide formed when adenosine is attached to a single phosphate group at the 5' position?

Accepted Answer

Adenosine 5'-monophosphate

Question 7

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

Accepted Answer

DNA is a linear polymer of nucleotides linked head-to-tail via monophosphate diester linkages.

Question 8

In a growing polynucleotide chain, which end has a free hydroxyl group?

Accepted Answer

3' end

Question 9

Which of the following best explains why ATP is considered a high-energy molecule?

Accepted Answer

It contains weak phosphoanhydride bonds between its phosphate groups.

Question 10

Which base pairing occurs in DNA due to hydrogen bonding?

Accepted Answer

Adenine pairs with thymine, guanine pairs with cytosine

Question 11

Which form of DNA double helix is characterized by a C2'-endo sugar pucker?

Accepted Answer

B-DNA

Question 12

What is the main structural difference between A-DNA and B-DNA?

Accepted Answer

A-DNA has a C3'-endo sugar pucker, while B-DNA has a C2'-endo sugar pucker.

Question 13

Which of the following statements about Z-DNA is correct?

Accepted Answer

Z-DNA contains repeats of the GC motif and has a zigzag backbone.

Question 14

Which configuration of the sugar pucker is found in the A-form of DNA?

Accepted Answer

C3'-endo

Question 15

If a polynucleotide sequence contains uracil, what type of nucleic acid is it?

Accepted Answer

RNA

Question 16

Which of the following is the correct order for constructing a polynucleotide chain?

Accepted Answer

Nucleotides are linked head-to-tail via monophosphate diester bonds, with new nucleotides added to the 3' end.

Question 17

Which of the following is a correct example of a nucleoside name?

Accepted Answer

Cytidine

Question 18

Which of the following best describes the role of base stacking in DNA?

Accepted Answer

Base stacking creates attractive forces that stabilize the double helix after hydrogen bonding brings the strands together.

Question 19

Which of the following is true regarding the directionality of polynucleotide chains?

Accepted Answer

Polynucleotide chains are typically written and synthesized from 5' to 3'.

Nucleotides & Nucleosides: Structures, Properties, and Nomenclature

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