alpha amino acids

functional groups

contain 2 - amino group and carboxylic acid

zwitterion

an internal acid-base reaction that forms a dipolar ion

physical properties

extremely polar

high melting points

extremely soluble in water

when are most amino acids are zwitterions

pH 6-7

at a lower pH

the zwitterion accepts a H+ ion on the basic CO2- group leaving only NH3+

the amino acid’s isoelectric point

pH at which an amino acid exists mainly in the zwitterion form

peptides

2 or more amino acids can link together by forming amide/peptide bonds

a dipeptide

formation of an amide bond between the NH2 group of one amino and the CO2H group of a second one

polypeptides

chains with 10-100 amino acids - dominant structural unit of proteins