Quantitative character: A heritable feature that varies continuously over a range rather than in an either-or fashion.
Quantitative genetics: The study of the inheritance of genetically complex traits.
Quantitative traits: Some characteristics that may be influenced by multiple genes and that is studied by the methods of quantitative genetics.
Quantitative trait locus (QTL): A region of genome that influence a quantitative trait
Quaternary structure: The particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide.
Quorum sensing: A mechanism that allows individual bacteria to sense the density of their population.