BS 161 1st Edition Lecture 3 Outline of Last Lecture I Carbon and functional groups Outline of Current Lecture II Protein structure III Amino acids IV R groups Current Lecture Proteins every process uses proteins important for mutation in evolution composed of one or more polypeptide chains held together and functioning as a unit Protein structure proteins are unbranched polymers of amino acids differ in the number and sequence of the twenty types of monomer amino acids Dehydration condensation reaction removal of a water molecule in order to bond two molecules Hydrolosis addition of a water molecule in order to separate two molecules Peptide short chain of amino acids mono 1 di 2 tri 3 oligo a few Polypeptide a single long chain of amino acids form protein Amino acid structure R groups also known as side chain group attached to asymmetric carbon determine the solubility shape and function of protein amino carboxyl and asymmetric carbon are present in all amino acids Classification and placement of R groups nonpolar usually found tucked away from protein surface hydrophobic polar generally on the protein surface electrically charged R group has a second carboxyl or amino group usually on the surface Organizational levels of protein structure 1 Primary the sequence of amino acids in all proteins all proteins have an amino terminal end and a carboxyl terminal end 2 Secondary 3D folding into one of two main types a Alpha helix tight coil b Beta pleated flat flexible sheet 3 Tertiary folding caused by R group interactions disulfide bond formation 4 Quaternary folding caused by polypeptide interactions hydrophobic bonds get buried on the inside hydrophilic bonds come to surface
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