nucleotides and nucleosides

Quiz Type

Practice

Subject

Biochemistry

Level

Level 500

Questions

20 questions

Created By

Racheal Appau

Quick Rules

Time limit: 10 minutes
Multiple attempts are not allowed
All questions must be answered to submit

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Question 1 of 20

Question 1

Multiple choice

What is the primary structural difference between a nucleotide and a nucleoside?

Nucleotides contain a phosphate group, while nucleosides do not.

Correct

Nucleosides contain a phosphate group, while nucleotides do not.

Nucleotides are only found in RNA, while nucleosides are found in DNA.

Nucleosides consist of a sugar and phosphate, while nucleotides consist only of a base.

Explanation

Nucleotides are composed of a nitrogenous base, a five-carbon sugar, and one or more phosphate groups, whereas nucleosides consist only of a nitrogenous base and a sugar.

Question 2

Multiple choice

Which part of a nucleotide contains the genetic information?

The phosphate group

The five-carbon sugar

The nitrogenous base

Correct

The overall structure of the nucleotide

Explanation

The nitrogenous base of a nucleotide is responsible for carrying the genetic information in DNA and RNA.

Question 3

Multiple choice

In DNA, which nitrogenous bases are classified as purines?

Adenine and Uracil

Guanine and Cytosine

Adenine and Guanine

Correct

Thymine and Cytosine

Explanation

Adenine and Guanine are classified as purines, which are characterized by their double-ring structure.

Question 4

Multiple choice

What role do nucleotides play in cellular metabolism?

They function only as structural components.

They are not involved in metabolism.

They serve as energy carriers and signaling molecules.

Correct

They only contribute to nucleic acid synthesis.

Explanation

Nucleotides serve important roles as energy carriers (like ATP) and in signaling pathways, in addition to being building blocks of nucleic acids.

Question 5

Multiple choice

Which of the following is considered a pyrimidine?

Adenine

Guanine

Thymine

Correct

Cytosine

Explanation

Thymine is a pyrimidine, characterized by its single-ring structure, along with Cytosine and Uracil.

Question 6

Multiple choice

What component differentiates RNA nucleotides from DNA nucleotides?

The presence of ribose sugar in RNA and deoxyribose in DNA

Correct

The presence of thymine in RNA and uracil in DNA.

The presence of a phosphate group in RNA only.

All bases in RNA are different from those in DNA.

Explanation

RNA nucleotides contain ribose sugar, while DNA nucleotides contain deoxyribose sugar, which is the primary difference between the two.

Question 7

Multiple choice

Which nucleotide is known as the energy currency of the cell?

GTP

UTP

ATP

Correct

CTP

Explanation

ATP (adenosine triphosphate) is commonly referred to as the energy currency of the cell due to its role in providing energy for metabolic processes.

Question 8

Multiple choice

What is the function of nucleoside reverse transcriptase inhibitors (NRTIs)?

To block the synthesis of RNA from DNA.

To inhibit the activity of RNA polymerase.

To prevent viral replication by targeting reverse transcriptase.

Correct

To enhance the replication of viral genetic material.

Explanation

NRTIs prevent viral replication by inhibiting the enzyme reverse transcriptase, crucial for converting viral RNA into DNA.

Question 9

Multiple choice

What are the building blocks of nucleic acids?

Lipids

Amino acids

Carbohydrates

Nucleotides

Correct

Explanation

Nucleotides are the building blocks of nucleic acids such as DNA and RNA.

Question 10

Multiple choice

In the context of nucleotides, what does the 'triphosphate' refer to?

The number of nitrogenous bases attached

The number of sugar molecules present

The presence of three phosphate groups

Correct

The addition of a carbon molecule

Explanation

The term 'triphosphate' refers to the three phosphate groups attached to a nucleotide, which can impact its energy-carrying capacity.

Question 11

Multiple choice

Which nucleotide pairs with adenine in DNA?

Cytosine

Thymine

Correct

Guanine

Uracil

Explanation

In DNA, adenine pairs with thymine through two hydrogen bonds.

Question 12

Multiple choice

What type of bond forms between adjacent nucleotides in a nucleic acid strand?

Hydrogen bonds

Ionic bonds

Covalent bonds

Correct

Metallic bonds

Explanation

Covalent bonds, specifically phosphodiester bonds, form between adjacent nucleotides in a nucleic acid strand.

Question 13

Multiple choice

Which nitrogenous base is not typically found in DNA?

Adenine

Thymine

Guanine

Uracil

Correct

Explanation

Uracil is typically found in RNA and replaces thymine in nucleic acid sequences.

Question 14

Multiple choice

What is the role of cyclic adenosine monophosphate (cAMP) in cells?

It acts as a structural component of membranes.

It serves as a secondary messenger in signaling pathways.

Correct

It assists in protein synthesis.

It functions solely as a nucleotide precursor.

Explanation

cAMP acts as a secondary messenger, playing a crucial role in transmitting signals within cells.

Question 15

Multiple choice

Which of the following describes the composition of a nucleoside?

A nitrogenous base and a phosphate group

A nitrogenous base and a sugar

Correct

A sugar and a phosphate group

A nitrogenous base, sugar, and a lipid

Explanation

A nucleoside consists of a nitrogenous base attached to a sugar molecule, without any phosphate groups.

Question 16

Multiple choice

Which molecule is produced during nucleotide metabolism and is involved in the regulation of cellular energy?

NADH

FADH2

GTP

Correct

CoA

Explanation

GTP (guanosine triphosphate) is produced during nucleotide metabolism and plays a role in energy regulation in cells.

Question 17

Multiple choice

What is the function of the enzyme nucleotidase?

To synthesize nucleic acids from nucleotides

To hydrolyze nucleotides into nucleosides and phosphates

Correct

To phosphorylate nucleosides into nucleotides

To replicate DNA strands

Explanation

Nucleotidase enzymes hydrolyze nucleotides, converting them into nucleosides and free phosphate groups.

Question 18

Multiple choice

What type of chemical reaction occurs during the formation of a nucleotide?

Hydrolysis

Condensation

Correct

Oxidation-reduction

Dehydration synthesis

Explanation

The formation of nucleotides from their components involves condensation reactions, specifically dehydration synthesis.

Question 19

Multiple choice

What is the primary structural difference between a nucleotide and a nucleoside?

Nucleotides contain a sugar and a phosphate group, while nucleosides do not.

Correct

Nucleosides contain a phosphate group, while nucleotides do not.

Nucleotides contain only nitrogenous bases, while nucleosides contain sugars.

Nucleotides and nucleosides are structurally identical but differ in their functions.

Explanation

A nucleotide consists of three components: a nitrogenous base, a pentose sugar, and a phosphate group. In contrast, a nucleoside consists only of the nitrogenous base and the sugar, lacking the phosphate group.

Question 20

Multiple choice

Which of the following statements correctly describes the components of nucleotides?

Nucleotides are made up of two types of sugars and a phosphate group.

Nucleotides are formed from a nitrogenous base, a sugar, and an amino acid.

Nucleotides consist of a nitrogenous base, a monosaccharide, and a lipid.

Nucleotides consist of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Correct

Explanation

Nucleotides are composed of three main components: a nitrogenous base, a pentose sugar (either ribose or deoxyribose), and one or more phosphate groups, which are essential for forming nucleic acids.