Summary
Highlights
Nucleic acids are large organic macromolecules, meaning they are large organic compounds made from thousands or hundreds of thousands of smaller molecules. There are two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
In living organisms, DNA is the main component of chromatin, which condenses into chromosomes. DNA in chromosomes contains genes, which hold directions for all functions, traits, and activities, including growth, reproduction, and heredity. RNA is involved in building specific proteins by assembling amino acids in the correct order, with proteins responsible for cellular functions.
As organic macromolecules, nucleic acids contain carbon, hydrogen, oxygen, and nitrogen, similarly to proteins. Unique to nucleic acids, they also contain the element phosphorus.
Both DNA and RNA are made of monomers called nucleotides. Each nucleotide consists of three compounds: a phosphate group (containing phosphorus), a five-carbon sugar (pentose), and a nitrogenous base. The pentose sugar in RNA is ribose, while in DNA it is deoxyribose (lacking one oxygen compared to ribose). The nitrogenous base is a weak base containing nitrogen.
DNA nucleotides contain one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G). RNA nucleotides also contain one of four bases: adenine (A), uracil (U), cytosine (C), or guanine (G). Both share adenine, cytosine, and guanine, but DNA has thymine while RNA has uracil.
Nucleotides assemble into nucleic acid polymers by forming bonds between the phosphate group of one nucleotide and the pentose sugar of another. RNA is a single-stranded nucleic acid, whereas DNA is a double-stranded nucleic acid. The two DNA strands are linked by hydrogen bonds between their nitrogenous bases.
In summary, nucleic acids are organic macromolecules (DNA and RNA) that transmit hereditary information and instruct protein construction. They are composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus. Their monomers are nucleotides, consisting of a phosphate group, a pentose sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base (A, T, C, G for DNA; A, U, C, G for RNA).