Download Proteins: Structure, Function, and Types - Prof. D. Freeman and more Study notes Chemistry in PDF only on Docsity! Chapter 12—Proteins Proteins function as the building and maintenance of the organism. They are the most plentiful organic chemicals of the body and are responsible for a great array of functions. o Catalytic proteins, or enzymes, catalyze the synthesis and utilization of proteins, carbohydrates, lipids, nucleic acids, and almost all other biomolecules o Transport proteins bind and carry specific molecules or ions from o place to place. o Regulatory proteins control cellular activity like lipid hormones and protein hormones such as insulin, which regulates glucose metabolism o Structural proteins give the physical shape, and the strength to maintain it, to structures in animals—the role played by cellulose in plants o Contractile proteins provide cells and organisms with the ability to change shape and move o Protective proteins defend against invaders and prevent or minimize damage after injury o Storage proteins provide a reservoir of nitrogen and other nutrients, especially when external sources are low or absent -Amino AcidsAmino Acids—the building blocks for naturally occurring polypeptides, compounds containing both a carboxyl group and an amino group attached to the same carbon atom o Mammals require all 20 -amino acids for protein synthesis but are unable to synthesize amino acids for protein synthesis but are unable to synthesize half of them. These 10 essential amino acids must be obtained from the diet o Categorized according to the R group, or side group, on the carbon: Nonpolar neutral have neutral hydrophobic side groups Polar neutral have hydrophilic side groups Polar acidic have acidic hydrophilic side groups Polar basic have basic hydrophilic side groups Peptides o Peptides: polyamides formed by -amino acids for protein synthesis but are unable to synthesize amino acids reacting with one another o Reaction: dehydration between the carboxyl and amino groups of different -amino acids for protein synthesis but are unable to synthesize amino acid molecules o The amino acids in the peptide, called amino acid monomers, are linked together by a peptide bond, the bond formed between the carbonyl carbon and the nitrogen o The functional group formed by this reaction is an amide group called the peptide group o Dipeptides, tripeptides, tetrapeptides, pentapeptides, hexapeptides, etc. o Polypeptides contains many amino acid monomers, exceeds 10-amino acids for protein synthesis but are unable to synthesize 20 amino acids o Oligopeptides refer to peptides smaller than polypeptides o Naming peptides All peptides contain an -amino acids for protein synthesis but are unable to synthesize amino group at one end and a -amino acids for protein synthesis but are unable to synthesize carboxyl group at the other end. The end containing the amino group is called the N-Amino Acidsterminal (amino-Amino Acids terminal) The end containing the carboxyl group is called the C-Amino Acidsterminal (carboxyl-Amino Acidsterminal) The C-amino acids for protein synthesis but are unable to synthesize terminal monomer, located on the far right, keeps it amino acid name. For each of the other amino acid monomers in a peptide, the –ine or –ic acid ending of the amino acid name is replaced by –yl Naming begins at the N-amino acids for protein synthesis but are unable to synthesize terminal side. o The physiological function of a peptide is determined largely by its amino acid sequence, the sequence of amino acid monomers Constitutional isomers: peptides with the same amino acids but a different sequence 3-amino acids for protein synthesis but are unable to synthesize D Structure of Proteins o Polypeptides containing more than 50 monomers are called proteins if they have physiological functions as individual polypeptide molecules
