5' → 3' Direction

Definition

This refers to the direction in which new nucleotides are added during DNA replication or transcription. The numbers 5' and 3' refer to the carbon atoms in a deoxyribose sugar molecule to which phosphate groups can attach, forming the backbone of the DNA strand.

Related terms

Deoxyribose: A five-carbon sugar that is a component of DNA molecules.

Phosphate Group: A functional group consisting of a phosphorus atom covalently bonded to four oxygen atoms; important in energy transfer.

Nucleotide: The basic building block of nucleic acids, composed of a sugar, a phosphate group, and one of several nitrogen-containing bases.