Glycine and alanine are different with respect to one substituent on the `alpha`-carbon. What are the other common substituent groups ?

Explanation

To address the question regarding the common substituent groups in glycine and alanine, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Glycine and Alanine**:
- Glycine (Gly) has the following structure:
- It consists of an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (H), and an alpha carbon (C).
- Alanine (Ala) has a similar structure but differs in one substituent:
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