Nucleic acid

Chemical structure

The term "nucleic acid" is the generic name for a family of nucleotides.

Each nucleotide consists of three components: a nitrogenous transfer RNA.

Nucleic acids are usually either single-stranded or double-stranded, though structures with three or more strands can form. A double-stranded nucleic acid consists of two single-stranded nucleic acids held together by hydrogen bonds, such as in the DNA double helix. In contrast, RNA is usually single-stranded, but any given strand may fold back upon itself to form secondary structure as in tRNA and rRNA. Within cells, DNA is usually double-stranded, though some viruses have single-stranded DNA as their genome. Retroviruses have single-stranded RNA as their genome.

The sugars and phosphates in nucleic acids are connected to each other in an alternating chain, linked by shared oxygens, forming a conventional nomenclature, the carbons to which the phosphate groups attach are the 3' end and the 5' end carbons of the sugar. This gives nucleic acids polarity. The bases extend from a glycosidic linkage to the 1"carbon of the pentose sugar ring. Bases are joined through N-1 of pyrimidines and N-9 of purins to 1' carbon of ribose through N-β glycosyl bond.

Types of nucleic acids

Ribonucleic acid

Main article: RNA

Ribonucleic acid, or RNA, is a nucleic acid polymer consisting of nucleotide monomers, which plays several important roles in the processes of translating genetic information from deoxyribonucleic acid (DNA) into proteins. RNA acts as a messenger between DNA and the protein synthesis complexes known as ribosomes, forms vital portions of ribosomes, and serves as an essential carrier molecule for amino acids to be used in protein synthesis.

Deoxyribonucleic acid

Main article: DNA

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA molecules is the long-term storage of information and DNA is often compared to a set of blueprints, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Nucleic acid components

Nucleobases

Main article: Nucleobase

Nucleobases are thymine. These are abbreviated as C, G, A, T, U, respectively.

Nucleobases are complementary, and when forming base pairs, must always join accordingly: cytosine-guanine, adenine-thymine (adenine-uracil when RNA). The strength of the interaction between cytosine and guanine is stronger than between adenine and thymine because the former pair has three hydrogen bonds joining them while the latter pair have only two. Thus, the higher the GC content of double-stranded DNA, the more stable the molecule and the higher the melting temperature.

Two main nucleobase classes exist, named for the molecule which forms their skeleton. These are the double-ringed pyrimidines. Adenine and guanine are purines (abbreviated as R), while cytosine, thymine, and uracil are all pyrimidines (abbreviated as Y).

Hypoxanthine and mutagen presence, through deamination (replacement of the amine-group with a hydroxyl-group). These are abbreviated HX and X.

Nucleosides

Main article: Nucleoside

Nucleosides are glycosylamines made by attaching a kinase enzyme), a nucleotide is produced. Nucleoside analogues, such as acyclovir, are used as antiviral agents.

Nucleotides and deoxynucleotides

Main article: Nucleotide

A nucleotide consists of a nucleoside and one or more metabolism, and signaling.

Nucleotides are named after the nucleoside on which they are based, in conjunction with the number of phosphates they contain, for example:

• Adenine bonded to ribose forms the nucleoside adenosine.
• Adenosine bonded to a phosphate forms adenosine monophosphate.
• As phosphates are added, adenosine diphosphate and adenosine triphosphate are formed, in sequence.

Nucleobases:	Cytosine)
Nucleosides:	Thymidine | Cytidine/Deoxycytidine
Nucleotides:	monophosphates (cADPR)
Deoxynucleotides:	monophosphates (dAMP, dGDP, TDP, dCDP) | triphosphates (dATP, dGTP, TTP, dCTP)
Ribonucleic acids:	snoRNA
Deoxyribonucleic acids:	mtDNA
Nucleic acid analogues:	morpholino
Cloning vectors:	phagemid | plasmid | lambda phage | cosmid | P1 phage | fosmid | BAC | YAC | HAC