A fatty acid is a carboxylic acid with a hydrocarbon chain. Its chain supplies much of the hydrophobic region when incorporated into a triglyceride or typical glycerophospholipid. See Biology 2e: fatty acids.
docosahexaenoic acid is a 22-carbon omega-3 fatty acid with six double bonds. Production and storage can require additional steps beyond an EPA-producing pathway.
eicosapentaenoic acid is a 20-carbon omega-3 fatty acid with five double bonds. Engineering its production requires coordinated desaturation, elongation and lipid-carrier handling.
alpha-linolenic acid is an 18-carbon omega-3 fatty acid with three double bonds. Its presence in conventional plant oils is distinct from substantial synthesis of EPA or DHA.
