Phosphoglycerids Phospholglycerides are esters of only two fatty acids, phosphoric acid and a trifunctional alcohol - glycerol (IUPAC name is 1,2,3-propantriol). The fatty acids are attached to the glycerol at the 1 and 2 positions on glycerol through ester bonds.
Phospholipids Phospholipids have a structure like a triglyceride,but contain a phosphate group in place of the third fatty acid. The phosphate group is polar and therefore capable of interacting with water molecules.
STEROIDS Steroids have a backbone of 4 carbon rings. Cholesterol is the precursor of several other steroids, including several hormones. It is also an important component of cell membranes.
REFERENCES Michael L. Shuler and Fikret Kargı, Bioprocess Engineering: Basic Concepts (2 nd Edition),Prentice Hall, New York, 2002. 1. James E. Bailey and David F. Ollis, Biochemical Engineering Fundementals (2 nd Edition), McGraw-Hill, New York, 1986.