What would be the net charge on the given amino acid at pH=14?
`H_2 N - overset(COOH)overset(|)CH-(CH_2)_4- overset(O)overset(||)C-OH`

Options

A. `-1`
B. `-2`
C. `+1`
D. `+2`

Explanation

To determine the net charge on the given amino acid at pH 14, we need to analyze the structure of the amino acid and how it behaves in a basic solution.

### Step-by-Step Solution:

1. **Identify the Functional Groups**: The given amino acid has an amino group (-NH2) and a carboxylic acid group (-COOH). The structure can be represented as:
\[ H_2N - CH(COOH) - (CH_2)_4 - C(=O) - OH \]

2. **Understand pH and Charge**: At pH 14, which is highly basic, the concentration of hydroxide ions (OH⁻) is high, and the concentration of hydrogen ions (H⁺) is low. In basic conditions, amino acids tend to lose protons from their acidic groups.

3. **Ionization of the Carboxylic Acid Group**: The carboxylic acid group (-COOH) will lose a proton (H⁺) and become negatively charged (-COO⁻). Therefore, at pH 14, the carboxylic acid group will be in the form:
\[ -COO^- \]

4. **Ionization of the Amino Group**: The amino group (-NH2) can accept a proton (H⁺) and become positively charged (-NH3⁺). However, in a highly basic environment (pH 14), the amino group remains in its neutral form (-NH2) because there are not enough H⁺ ions to protonate it.

5. **Calculate the Net Charge**:
- The amino group contributes a charge of 0 (as it is neutral).
- The carboxylic acid group contributes a charge of -1 (as it is deprotonated).
- The side chain (R group) does not affect the overall charge unless specified, but in this case, it is neutral.

Therefore, the total charge is:
\[ 0 + (-1) = -1 \]

6. **Final Charge Calculation**: Since there is another -COOH group in the structure (as indicated by the presence of the side chain), it will also deprotonate at pH 14, contributing another -1 charge. Thus, the total charge becomes:
\[ -1 + (-1) = -2 \]

### Conclusion:
The net charge on the given amino acid at pH 14 is **-2**.

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