Nucleotides and Nucleic Acids

These flashcards cover key concepts, definitions, and structural features of nucleotides and nucleic acids discussed in the lecture notes.

What are the main functions of nucleotides?

Energy for metabolism (ATP), enzyme cofactors (NAD+), signal transduction (cAMP).

What are the functions of nucleic acids?

They store genetic information (DNA), transmit genetic information (mRNA), process genetic information (ribozymes), and synthesize proteins (tRNA and rRNA).

What components make up a nucleotide?

A nitrogenous base, a pentose sugar, and a phosphate group.

What are the two types of nitrogenous bases found in nucleotides?

Purines (adenine, guanine) and pyrimidines (cytosine, thymine, uracil).

What type of bond connects the pentose ring to the nucleobase in nucleotides?

N-glycosidic bond.

What is the effect of the phosphate group on a nucleotide at neutral pH?

The phosphate group is negatively charged.

What are the differences between DNA and RNA regarding the pentose sugar?

DNA contains 2'-deoxy-D-ribofuranose, while RNA contains D-ribofuranose.

How do purines and pyrimidines differ in their structures?

Purines have a two-ring structure, while pyrimidines have a single-ring structure.

Which bases are found only in RNA?

Uracil is found only in RNA.

What is Watson-Crick base pairing?

A pairs with T, and C pairs with G in double-stranded DNA.

What happens during DNA denaturation?

Hydrogen bonds are broken, and the two strands separate, while covalent bonds remain intact.

What is the role of DNA polymerase in replication?

It catalyzes the synthesis of a new DNA strand using the original strand as a template.

What is the significance of the melting temperature (Tm) of DNA?

Tm depends on the base composition and length of DNA; high CG content increases Tm.

What does RNA interference technology do?

It employs short RNA molecules to inhibit gene expression or translation.

What are coenzymes?

Molecules that assist enzymes during the catalysis of reactions, often derived from nucleotides.

How does UV light affect DNA?

UV light can induce dimerization of pyrimidines, leading to potential mutations.

What is tautomerism in nucleobases?

It refers to the structural isomerism where the position of protons shifts, affecting bonding and stability.

What type of reaction leads to deamination of nucleobases?

A slow reaction that results in the conversion of cytosine to uracil.

What is the impact of depurination in DNA?

It leads to the loss of purines from the DNA strand, creating apurinic sites.

What is base stacking in nucleic acids?

Interactions between adjacent bases in a DNA molecule contributing to its stability.

How do cells repair mutations caused by oxidative damage?

Cells have mechanisms to correct such modifications, but not all are fixable.