Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids Overview

Nucleic acids are biopolymers that store genetic information and are composed of three main components: a sugar (2-deoxy-D-ribose in DNA), a phosphate group, and a nitrogenous base (either purines: adenine, guanine or pyrimidines: cytosine, thymine).

Nucleosides and Nucleotides

A nucleoside consists of a sugar linked to a nitrogenous base, while a nucleotide is a nucleoside phosphorylated at the sugar's hydroxyl group. Nucleotide names are abbreviated with a lowercase 'd' and respective base initials followed by a code indicating the number of phosphates (e.g., dCMP, dAMP).

DNA Structure

The primary structure of DNA includes deoxyribose sugars linked by phosphate groups. The secondary structure is characterized by: two antiparallel helical chains, with base pairs (A-T, G-C) forming the interior and the sugar-phosphate backbone on the exterior. Each helix turn consists of 10 base pairs and spans 34 Å.

DNA Replication and Protein Synthesis

DNA replication relies on specific base pairing and involves unwinding the helix and complementary base pairing to form two identical strands. Protein synthesis involves decoding DNA through codons to form amino acids, facilitated by mRNA, tRNA, and ribosomes.

RNA Types

RNA differs from DNA by having ribose and uracil instead of thymine. mRNA is responsible for carrying the genetic code from DNA to ribsomes for translation. rRNA comprises ribosomal structures, while some RNA can also function as biocatalysts (ribozymes).

Nucleotide Functions

ATP serves as an energy currency in cells by hydrolyzing phosphate bonds. NAD and FAD are coenzymes facilitating biochemical reactions. Vitamin B12 is a crucial nucleotide-containing molecule for red blood cell development, derived from dietary sources.