Answer:
H, -NH2 and -COOH groups
Explanation:
Lets take the example of simplest amino acid i-e Glycine
It has four functional groups:
1- H-atom
2- -NH2 amino group
3- -COOH carboylic group
4 -R group
Every amino acids have same H ,-NH2 and -COOH groups. The difference is in -R groups.
