Nucleic Acids

Steroid hormones are secreted by cells of adrenal cortex and endocrine cells of gonads. All steroid hormones are lipid derived from cholesterol. Many enzymes are involved in the biosynthetic pathway of steroid hormonessome of which are located in SER membrane and some occur in mitochondria. Protein hormones are secreted by parathyroid, pituitary glands, secretory cells of hypothalamus and pancreas. These are small peptides of 3-200 amino acid monomers. Amino Acid Derivative (AAD) hormones are smallest hormones and derived from tyrosine, histidene and tryptophan.