Lipid Derivatives BI 171 [Handout]
Representative Lipid Derivatives of Biological Importance
- Phospholipids - Glycerol joined to two fatty acid molecules, the third place is occupied by a phosphate group; major
lipid constituent of cell membranes; found in human plasma; abundant in seeds and egg yolk; found in high concentrations in brains, nerves, and neural tissues generally.
- Waxes - Lipids composed of fatty acids with long chain alcohols, not glycerol.
- Suberin - Waterproofing material found in cell walls of cork
- Cutin - Waterproofing substance covering the epidermis of
leaves, stems, and fruits.
- Carotenoids - Plant and animal pigments.
- Carotenes - Occur in all leaves; responsible for orange, red, , yellow, and cream-white colors of tomatoes, carrots,
egg yolk, milk, and other plant and animal products; Vitamin A is a derivative of carotenes; a further derivative of Vitamin A, retinene, acts as a photoreceptor in the retina of the eye.
- Xanthophylls - Examples include lutein, a yellow substance in autumn leaves, and fucoxanthin, a pigment in brown
and other algae.
- Steroids - All are related in that they possess a structure
similar to that of cholesterol; regulate sexual development and influence numerous aspects of metabolism.
- Cholesterol - Present in all animal cells, blood, and particularly nervous tissue; found in cell membranes.
- Vitamin D - Synthesized in human skin upon exposure to
- Cortisone - Hormone produced by adrenal glands of vertebrates.
- Androgens - Male sex hormones; testosterone most influential.
- Estrogens - Female sex hormones; progesterone most powerful.
- Bile Salts - Emulsify fats prior to digestion in vertebrates.
- Porphyrins - Pigment compounds distantly related to lipids which
are combined with proteins.
- Chlorophyll - Green pigments of photosynthetic organisms.
- Hemoglobin - Oxygen-transporting substance in blood or tissues of
- Cytochromes - Electron-carrying proteins involved in respiration
- Bile pigments - Bilirubin (reddish) and biliverdin (green) have their origin in hematin, a derivative of hemoglobin;
responsible for brown color of feces.
- Other lipoid substances - Among other lipid-like compounds in living matter are xanthocyanins, plant pigments; Vitamin E, the antihemorrhagic vitamin; and Coenzyme Q, a substance
that functions in respiration.