They have different functional groups. Methionine is considered a group 1 non polar amino acid. The R group of this amino acid has either aliphatic or aromatic groups which makes them hydrophobic. Methionine is one of the two amino acids that possess a sulfur atom. It plays a central role in protein biosynthesis such as translation. Lysine is considered a basic amino acid. Lysine is also positively charged and polar. This makes it hydrophillic, which means it "favors water". Each amino acid has an R group that makes them differ from one another. The sequence of the R group generates their unique
