Nucleic Acids and Carbohydrates: Structure, Function, and Biological Roles

What are the three components of a nucleotide?

A phosphate group, a 5-carbon sugar (pentose), and a nitrogenous base.

What distinguishes ribose from deoxyribose?

Ribose has a hydroxyl group (-OH) on the 2' carbon, while deoxyribose has a hydrogen atom (-H) instead.

Name the purines found in nucleic acids.

Adenine (A) and Guanine (G).

What are the pyrimidines in nucleic acids?

Cytosine (C), Uracil (U - RNA only), and Thymine (T - DNA only).

What type of bond forms between nucleotides during polymerization?

Phosphodiester bond.

In which direction does the sugar-phosphate backbone of nucleic acids run?

5' to 3' direction.

What is the role of activated nucleotides in polymerization?

They provide energy for the polymerization process.

Describe the secondary structure of DNA.

Two antiparallel strands form a double helix with a sugar-phosphate backbone and base pairs facing inward.

Which bases pair together in DNA?

Adenine pairs with Thymine (A-T) and Guanine pairs with Cytosine (G-C).

What stabilizes the DNA double helix structure?

Hydrophobic interactions and van der Waals forces.

What is the primary structure of RNA?

Contains ribose sugar, a sugar-phosphate backbone, and bases A, U, G, C.

What is a ribozyme?

An RNA molecule that acts as an enzyme, catalyzing chemical reactions.

What is the general formula for monosaccharides?

The formula is (CH2O)n, where n is the number of carbon-hydrate units.

What distinguishes aldoses from ketoses?

Aldoses have the carbonyl group at the end of the carbon chain, while ketoses have it within the chain.

What are glycosidic linkages?

Covalent bonds formed between monosaccharides during condensation reactions.

What is starch and its function?

A plant storage molecule made of alpha-glucose, used for energy storage.

What is the structural component of plant cell walls?

Cellulose, made of beta-glucose joined by beta-1,4 linkages.

What is chitin and where is it found?

A structural polysaccharide found in fungal cell walls and arthropod exoskeletons.

How do carbohydrates contribute to cell identity?

Monosaccharides attach to proteins and lipids on cell membranes, serving as identification badges.

What enzymes hydrolyze starch and glycogen?

Amylase for starch and phosphorylase for glycogen.

What type of linkages do structural polysaccharides like cellulose have?

Beta-1,4 linkages.

What is the significance of the 2' -OH group in RNA?

It makes RNA less stable and more reactive than DNA.

What is the process of DNA replication?

Strands separate, free deoxyribonucleotides pair with template bases, and phosphodiester linkages form.