Which of the following statements about amino acids is false

Options

A. They are constituents of all proteins
B. Alanine having one amino and one carboxylic group.
C. Most naturally occuring amino acids have D-configuration.
D. Glycine is the only naturally occuring amino acid which is optically inactive.

Explanation

To determine which statement about amino acids is false, let's analyze the statements one by one.

### Step 1: Understand the Structure of Amino Acids
Amino acids are organic compounds that contain both an amino group (-NH2) and a carboxylic acid group (-COOH). They are the building blocks of proteins.

**Hint:** Recall that amino acids have a general structure consisting of a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group (side chain).

### Step 2: Analyze the Statements
1. **Statement A:** Amino acids are linked together by peptide bonds to form proteins.
- This statement is true. Amino acids indeed link together through peptide bonds to form proteins.

2. **Statement B:** Alanine has one amino group and one carboxyl group.
- This statement is also true. Alanine is an alpha-amino acid with one amino group and one carboxyl group.

3. **Statement C:** Most naturally occurring amino acids have D-configuration.
- This statement is false. Most naturally occurring amino acids are in the L-configuration, not D-configuration. The L-configuration is predominant in biological systems.

4. **Statement D:** Glycine is the only naturally occurring amino acid that is optically inactive.
- This statement is true. Glycine does not have a chiral center because its R group is a hydrogen atom, making it optically inactive.

### Step 3: Identify the False Statement
Based on the analysis:
- Statement C is the false statement because most naturally occurring amino acids have L-configuration, not D-configuration.

**Final Answer:** The false statement is C: "Most naturally occurring amino acids have D-configuration."