Why are amino acids also called `alpha` - amino acids ?

Options

A. They have `alpha` - carbon with amino and acid group.
B. They are rotated clockwise.
C. They are rotated anti - clockwise
D. They rotate the plane of polarized light to the right.

Answer

To understand why amino acids are called "alpha-amino acids," let's break down the explanation step by step:

### Step-by-Step Solution:

1. **Definition of Amino Acids**:
- Amino acids are organic compounds that serve as the building blocks of proteins. They contain both an amino group (-NH2) and a carboxylic acid group (-COOH).

2. **Structure of Amino Acids**:
- Each amino acid has a central carbon atom, known as the alpha carbon (Cα). This carbon is bonded to four different groups:
- An amino group (-NH2)
- A carboxylic acid group (-COOH)
- A hydrogen atom (-H)
- A variable side chain (R group) that determines the specific type of amino acid.

3. **Identification of the Alpha Carbon**:
- The term "alpha" refers to the position of the carbon atom in relation to the functional groups. The alpha carbon is the first carbon atom that is attached to the functional groups (amino and carboxylic acid) in the structure of the amino acid.

4. **Conclusion**:
- Since the central carbon atom (alpha carbon) is bonded to both the amino group and the carboxylic acid group, amino acids are specifically referred to as "alpha-amino acids."

### Final Answer:
Amino acids are called "alpha-amino acids" because they contain an alpha carbon that is bonded to both an amino group (-NH2) and a carboxylic acid group (-COOH).

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