<prompt> Most non polar amino acid is:LeucineGlycineArginineLysine  <response>: Polar and non polar amino acids:Polarity : Amino acids are classified into 4 groups based on their polarity. The polarity in turn reflects the functional role of amino acids in protein structure. Non-polar amino acids: These amino acids are also referred to as hydrophobic water hating. They have no charge on the R group. The amino acids included in this group are - alanine, leucine, isoleucine, valine, methionine, phenyl-alanine, tryptophan and proline. Polar amino acids with no charge on R group: These amino acids, as such, carry no charge on the R group. They however possess groups such as hydroxyl, sulfhydryl and amide and participate in hydrogen bonding of protein structure. The simple amino acid glycine where R H is also considered in this category. The amino acids in this group are - glycine, serine, threonine, cysteine, glutamine, asparagine and tyrosine. Polar amino acids with positive R group: The three amino acids lysine, arginine and histidine are included in this group. Polar amino acids with negative R group: The dicarboxylic monoamino acids- aspartic acid and glutamic acid are considered in this group. 