The molecules that form starch, glycogen and cellulose are formed by hundreds of molecules of just one type of monosaccharides (glucose, in this cases), linked through glycosidic linkages. These polysaccharides are typical examples of homopolysaccharides.
If the polysaccharide is formed by different types of monosaccharides, then it is called a heteropolysaccharide. Hyaluronic acid, formed by thousands of alternant units of glucuronic acid and N-acetylglucosamine, is an example of heteropolysaccharides.
Hyaluronic acid is an important component of the extracellular matrix in the skin and the conective tissue. This compound has received lately a lot of attention from the media as an antiaging agent.
ISWT 10. Aminoacids. Proteins and its structure. Enzymes.
Amino acids are biologically important organic compounds composed of amine (-NH2) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids.
Proteinogenic amino acids are amino acids that are precursors to proteins, and are produced by cellular machinery coded for in the genetic code of any organism. There are 22 standard amino acids, but only 21 are found in eukaryotes. Of the 22, selenocysteine and pyrrolysine are incorporated into proteins by distinctive biosynthetic mechanisms. The other 20 are directly encoded by the universal genetic code. Humans can synthesize 11 of these 20 from each other or from other molecules of intermediary metabolism. The other 9 must be consumed (usually as their protein derivatives) in the diet and so are thus called essential amino acids. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Protein structure is the biomolecular structure of a protein molecule. Each protein is a polymer – specifically a polypeptide – that is a sequence formed from various L-α-amino acids (also referred to as residues).
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