BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Two amino acids, serine and threonine, contain aliphatic hydroxyl groups (that is, an oxygen atom bonded to a hydrogen atom, represented as ―OH). Tyrosine possesses a hydroxyl group in the aromatic ring, making it a phenol derivative.

Detailed explanation-2: -Six amino acids have side chains that are polar but not charged. These are serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), glutamine (Gln), and tyrosine (Tyr).

Detailed explanation-3: -Threonine is an other hydroxyl-containing amino acid. It differs from serine by having a methyl substituent in place of one of the hydrogens on the carbon and it differs from valine by replacement of a methyl substituent with a hydroxyl group. Note that both the and carbons of threonine are optically active.

Detailed explanation-4: -Tryptophan contains an -amino group, an -carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3.