BIOL 123 Lecture Notes - Lecture 28: Hydrophile, Dill, Hemoglobin
Document Summary
Proteins = molecules composed of one or more chains of amino acids: structure differences cause functional differences. Most cells contain hundreds of different enzymes: enzymes = proteins that promote chemical reactions. Other types of proteins form structures on or outside the body: example: keratin, the principal protein of hair, horns, nails, scales, and feathers. Proteins are formed from chains of amino acids. Proteins are polymers consisting of chains of amino acids joined by peptide bonds. Amino acids = all consists of a central carbon bonded to three different functional groups: a nitrogen-containing amino group (-nh2), a carboxylic acid group (-cooh), and an r group that varies among different amino acids. The sulfhydryl r group of one amino acid, cysteine, can form covalent disulfide bonds with the sulfur in another cysteine molecule. Amino acids are joined to form chains by dehydration synthesis. Like polysaccharides and lipids, proteins are formed by dehydration synthesis.
