DNA ligase
An enzyme that joins the 5 end of one polynucleotide chain to the 3 end of another (or the same) polynucleotide chain.

DNA Methylation
Addition of a methyl group to a cytosine base in the DNA molecule. This process plays a role in gene expression that is not completely understood

DNA polymerase
An enzyme that catalyzes the synthesis of DNA using a template DNA molecule, a primer, and free deoxyribonucleotides.

DNA sequence
The relative order of base pairs, whether in a DNA fragment, gene, chromosome, or an entire genome. See also: base sequence analysis

Dobzhansky, Theodosius
A geneticist and zoologist best known for his research in population genetics using the fruit fly. His study of the evolution of races led to the discovery of genetic diversity within species, and confirmed his belief that genetic variation leads to better adaptability.

Domain
A discrete portion of a protein with its own function. The combination of domains in a single protein determines its overall function