Lipid as signals, Cofactors and pigments

a) Have active role in metabolic traffic as metabolites and messenger.

b) Some serve as potent signals as hormones carried in the blood from one tissue to another.

c) As enzyme cofactor in electron-transfer reaction in chloroplast and mitochondria.

d) Helps in absorbing visible light for vision and photosynthesis and natural colorations.

Phosphatidylinositol and Sphingosine derivatives as intercellular signals

a) Acts at several levels to regulate cell structure and metabolism.

b) Serve as specific binding site for certain cytoskeleton proteins.

c) Serve as a source of intercellular messenger.

d) Involved in regulation of cell division, differentiation, migration and programmed cell death.