The difference between one amino acid and another is found in the :

Options

A. peptide bond
B. R group
C. carboxyl group
D. amino group

Explanation

To answer the question "The difference between one amino acid and another is found in the:", we need to analyze the components of an amino acid and identify where the variations occur.

### Step-by-Step Solution:

1. **Understanding Amino Acids**:
- Amino acids are the building blocks of proteins. Each amino acid has a basic structure that includes an amino group (NH2), a carboxyl group (COOH), and a central carbon atom.

2. **Identifying Components**:
- The main components of an amino acid are:
- Amino group (NH2)
- Carboxyl group (COOH)
- Central carbon atom
- R group (side chain)

3. **Role of the R Group**:
- The R group, also known as the side chain, is unique to each amino acid. It is this side chain that determines the specific properties and characteristics of each amino acid.

4. **Classifying Amino Acids**:
- Amino acids can be classified based on their R groups:
- Non-polar (hydrophobic) amino acids (e.g., glycine, tryptophan)
- Polar (hydrophilic) amino acids, which can be further classified into:
- Acidic amino acids (e.g., aspartic acid)
- Basic amino acids (e.g., lysine)
- Neutral amino acids (e.g., serine)

5. **Conclusion**:
- Since the R group is the component that varies among different amino acids, the answer to the question is that the difference between one amino acid and another is found in the **R group**.

### Final Answer:
The difference between one amino acid and another is found in the **R group**.

---