A1.2 Nucleic Acids

DNA

Deoxyribonucleic acid, the genetic material of all living organisms.

RNA

Ribonucleic acid, a polymer formed by condensation of nucleotide monomers.

Nucleotide

The building block of nucleic acids, composed of a phosphate, a sugar, and a nitrogen base.

Sugar–phosphate backbone

The structural framework of nucleic acids, formed by sugar and phosphate bonds.

Complementary base pairs

Specific pairs of nitrogen bases in nucleic acids that bond together; adenine pairs with thymine, and guanine pairs with cytosine.

Antiparallel

Describes the orientation of the two strands of DNA, which run in opposite directions.

Polynucleotide

A polymer consisting of a sequence of nucleotides, such as DNA or RNA.

Genetic code

The set of rules by which information encoded in genetic material is translated into proteins.

Transcription

The process of copying a segment of DNA into messenger RNA (mRNA).

Translation

The process of translating the mRNA sequence into a polypeptide chain (protein).

Hydrogen bonding

The weak attraction between a hydrogen atom and an electronegative atom, important in base pairing in DNA.

Virus

A microscopic infectious agent that cannot reproduce without a host cell.

Homeostasis

The ability of living organisms to maintain stable internal conditions.

Metabolism

The set of life-sustaining chemical transformations within the cells of organisms.

Gene expression

The process by which genetic information is converted into the structures and functions of a cell.

Purine

A type of nitrogenous base that includes adenine and guanine.

Pyrimidine

A type of nitrogenous base that includes cytosine, thymine, and uracil.

Double helix

The spiral shape formed by two strands of DNA held together by base pairing.

RNA polymerase

The enzyme responsible for synthesizing RNA from a DNA template during transcription.

tRNA

Transfer RNA, responsible for bringing amino acids to the ribosome during protein synthesis.

mRNA

Messenger RNA, a type of RNA that carries genetic information from DNA to the ribosome.

Codon

A sequence of three nucleotides in mRNA that specifies an amino acid.

Chargaff's rule

In DNA, the amount of adenine equals thymine, and the amount of guanine equals cytosine.