LIFE SCIENCE

Detailed explanation-1: -Two amino acids have acidic side chains at neutral pH. These are aspartic acid or aspartate (Asp) and glutamic acid or glutamate (Glu).

Detailed explanation-2: -Glutamic acid, aspartic acid, and cysteic acid are examples of acidic amino acids.

Detailed explanation-3: -Among the 20 common amino acids, five have a side chain which can be charged. At pH=7, two are negative charged: aspartic acid (Asp, D) and glutamic acid (Glu, E) (acidic side chains), and three are positive charged: lysine (Lys, K), arginine (Arg, R) and histidine (His, H) (basic side chains).

Detailed explanation-4: -Cysteine (Cys/C) is the only amino acid with a sulfhydryl group in its side chain.

Detailed explanation-5: -There are basically four different classes of amino acids determined by different side chains: (1) non-polar and neutral, (2) polar and neutral, (3) acidic and polar, (4) basic and polar.