Nucleic Acids Overview

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Questions and Answers

What is the consequence of incorporating a nucleoside analog into viral DNA?

It prevents the formation of sugar-phosphate bonds. (correct)

It initiates viral replication.

It allows the virus to mutate quickly.

It enhances protein synthesis in the virus.

Which enzyme is primarily inhibited in the treatment of AIDS to prevent viral replication?

RNA polymerase

Ligase

DNA polymerase

Reverse transcriptase (correct)

What type of carbohydrates were previously thought to be hydrates of carbon?

Disaccharides

Polysaccharides

Simple sugars (correct)

Starches

Which of the following carbohydrates is a disaccharide?

Lactose Signup and view all the answers

Which two types of inhibitors are combined in AIDS treatment?

Protease and reverse transcriptase inhibitors Signup and view all the answers

What is the role of protease inhibitors in AIDS treatment?

They prevent the synthesis of viral proteins. Signup and view all the answers

In photosynthesis, carbon atoms are combined with which elements to form carbohydrates?

Hydrogen and oxygen Signup and view all the answers

Which of the following is NOT a characteristic of carbohydrates?

They store genetic information. Signup and view all the answers

What determines whether a monosaccharide is classified as a D or L isomer?

The arrangement of the –OH group on the chiral carbon farthest from the carbonyl Signup and view all the answers

Which of the following is a characteristic of D-glucose?

It is an aldohexose found in fruits and vegetables. Signup and view all the answers

What is the main health issue associated with galactosemia?

Accumulation of galactose leading to severe health problems Signup and view all the answers

Which monosaccharide is specifically classified as an aldohexose obtained from lactose?

Galactose Signup and view all the answers

What distinguishes D-glucose from D-galactose in terms of their Fischer projections?

The –OH group at carbon 4 is arranged differently. Signup and view all the answers

Which statement about monosaccharides in their cyclic form is true?

They result from the reaction of a carbonyl group with a hydroxyl group. Signup and view all the answers

What type of monosaccharide is xylose classified as?

Aldopentose Signup and view all the answers

Which of the following is NOT considered one of the most common hexoses?

Maltose Signup and view all the answers

What is the most stable form of pentoses and hexoses?

Five- or six-atom rings Signup and view all the answers

What type of sugar is fructose classified as?

A ketohexose Signup and view all the answers

When drawing the Haworth structure of fructose, where is the carbonyl group located?

At carbon 2 Signup and view all the answers

What distinguishes the α and β isomers of fructose?

The orientation of the new hydroxyl group on carbon 1 Signup and view all the answers

What occurs during the formation of the Haworth structure?

The hydroxyl group on C5 reacts with the carbonyl carbon Signup and view all the answers

What determines the sweetness of fructose compared to sucrose?

The structure of the molecule Signup and view all the answers

Which carbon atoms are positioned at the base of the hexagon while folding the chain for the Haworth structure?

C2 and C3 Signup and view all the answers

What type of reaction leads to the formation of the Haworth structure?

Condensation Signup and view all the answers

What distinguishes the ends of a nucleic acid strand?

One end has a free 5’-phosphate terminal, and the other has a free 3’-hydroxyl group. Signup and view all the answers

Which of the following is a characteristic of a typical virus?

Is composed of a nucleic acid that can either be DNA or RNA, but not both. Signup and view all the answers

In which type of nucleic acid is ribose found?

RNA Signup and view all the answers

According to the pairing rules, which base pairs with adenine in DNA?

Thymine Signup and view all the answers

What is the relationship between the number of purines and pyrimidines in DNA?

The number of purines is equal to the number of pyrimidines. Signup and view all the answers

Which of the following structures represents a nucleotide?

A sugar attached to both a phosphate group and a nitrogenous base. Signup and view all the answers

What structure do DNA strands form, and who proposed this model?

Double helix; James Watson and Francis Crick. Signup and view all the answers

What type of molecule is cytidine-5’-monophosphate (CMP)?

Nucleotide found in RNA. Signup and view all the answers

What is the process called when D-glucose changes between the α and β forms?

Mutarotation Signup and view all the answers

Which of the following monosaccharides is known as a ketohexose?

Fructose Signup and view all the answers

What structural feature distinguishes α-D-glucose from β-D-glucose?

The -OH group on C1 Signup and view all the answers

What type of bond forms in the Haworth structure of monosaccharides?

Covalent bond Signup and view all the answers

In the process of oxidation of an aldose, which functional group is oxidized?

Aldehyde group Signup and view all the answers

What is formed when glucose is reduced?

D-glucitol (D-sorbitol) Signup and view all the answers

What occurs when an aldehyde group with an adjacent hydroxyl group is oxidized?

It forms a carboxylic acid Signup and view all the answers

Which monosaccharide is structurally similar to glucose but differs in the arrangement of the –OH group on C4?

Galactose Signup and view all the answers

What type of glycosidic bond is present in glycogen?

α-1,6-glycosidic bonds Signup and view all the answers

Which polysaccharide makes up about 20% of starch?

Amylose Signup and view all the answers

What is the role of amylase in relation to starch?

It digests starch in saliva Signup and view all the answers

What type of glycosidic bond is found in cellulose?

β-1,4-glycosidic bonds Signup and view all the answers

Which statement accurately describes glycogen?

It is stored in the liver and muscle of animals. Signup and view all the answers

What provides about 50% of our nutritional calories?

Glucose obtained from carbohydrates Signup and view all the answers

What distinguishes amylose from amylopectin?

Amylose has no branches. Signup and view all the answers

What structure does amylose predominantly take?

Coiled helix Signup and view all the answers

Study Notes

Nucleic Acids

Nucleic acids are large molecules in cell nuclei, storing information for cellular growth and reproduction.
Two main types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Both are unbranched polymers of nucleotides.
Each nucleotide has three components: a base, a five-carbon sugar, and a phosphate group.
Bases are derivatives of pyrimidine or purine.
In RNA, the five-carbon sugar is ribose.
In DNA, the five-carbon sugar is deoxyribose.
Nucleosides are a combination of a sugar and a base, formed by an N-glycosidic bond.
Nucleotides are nucleosides with a phosphate group bonded to the sugar's 5' carbon.
Only the 5' monophosphate nucleotides are in RNA and DNA.

Nucleosides and Nucleotides

Nucleosides are formed when a nitrogenous base bonds to a sugar (ribose or deoxyribose).
Nucleotides are formed when a phosphate group bonds to the 5' carbon of a nucleoside.

Primary Structure of Nucleic Acids

Nucleic acids are polymers of nucleotides.
Nucleotides are linked by phosphodiester bonds.
The sequence of bases forms the primary structure.
Nucleic acid sequences are read from the 5' end to the 3' end.

DNA Structure

DNA is a double helix.
Two polynucleotide strands wind around each other.
Sugar-phosphate backbones are on the outside, and bases are paired on the inside.
Base pairs are held together by hydrogen bonds (A with T, G with C).
The strands run in opposite directions (antiparallel).

Viruses

Viruses are small particles containing nucleic acid (DNA or RNA) and protein coat.
They require a host cell to replicate.

Reverse Transcription

Retroviruses use reverse transcriptase to synthesize DNA from RNA.
The viral DNA then integrates into the host cell's DNA.
Nucleoside analogs can inhibit reverse transcriptase, preventing viral replication.

Acquired Immune Deficiency Syndrome (AIDS)

AIDS is caused by the HIV virus.
HIV infects and destroys T4 lymphocyte cells.
Treatment for AIDS often combines reverse transcriptase inhibitors with protease inhibitors.

Carbohydrates

Carbohydrates are composed of carbon, hydrogen, and oxygen.
Simple sugars (monosaccharides) have the formula C_n(H₂O)_n.
Monosaccharides can be aldoses (aldehyde group) or ketoses (ketone group).
Disaccharides are formed from two monosaccharides linked by a glycosidic bond.
Common disaccharides include sucrose, lactose, and maltose.
Polysaccharides are polymers of monosaccharides (e.g., starch, glycogen, cellulose).

Classification of Carbohydrates

Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose).
Disaccharides: Two monosaccharides joined (e.g., sucrose, lactose, maltose).
Polysaccharides: Many monosaccharides joined (e.g., starch, glycogen, cellulose).

Naming of Carbohydrates

Aldoses: Sugars with an aldehyde group.
Ketoses: Sugars with a ketone group.
Pentose: 5-carbon sugars.
Hexose: 6-carbon sugars.

Mutarotation of Carbohydrates

In aqueous solution, cyclic monosaccharides can interchange between alpha and beta forms.

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Description

Explore the essential components and structures of nucleic acids, including DNA and RNA. This quiz covers the basics of nucleotides and nucleosides, their formation, and their roles in cellular functions. Test your understanding of these vital biological molecules!