In: Biology
Hydrophilic amino acids have polar side chains that are attracted to water.
Explanation: Amino acids are building blocks of
proteins and are composed of a carboxyl group, an amino group, a
hydrogen atom and a distinctive side chain. These all are bonded to
a carbon atom, the
-carbon.
Amino acids can be classified based on the properties of their side chain. Particularly based on the polarity (tendency to interact with water at physiological pH) nature of the side chain, amino acids are categorized into: hydrophobic amino acids and hydrophilic amino acids.
Hydrophobic amino acids (amino acids with nonpolar side chain): Among standard amino acids, nine amino acids contain nonpolar side chain. These are glycine, alanine, valine, leucine, isoleucine, proline, methionine, phenylalanine and tryptophan.
Hydrophilic amino acids (amino acids with polar side chain):
Six amino acids contain uncharged polar side chain- serine, threonine, cysteine, asparagine, glutamine, and tyrosine. Three amino acids, serine, threonine, and tyrosine contain hydroxyl groups(-OH) attached to the side chain. These hydroxyl groups make them attracted to water.
Three amino acids contain positively charged polar side chain. These are lysine, arginine, and histidine.
Two amino acids contain negatively charged polar side chain. These amino acids are aspartate and glutamate.