A mixture of three amino acids X-(pH = 3.2), Y-(pH = 5.7, and Z-(pH = 9.7) under electrophoresis at pH = 7.7, in which direction will each componeat of the mixture move?

Options

A. X to anode, Y and Z to cathode
B. X to anode Y stationary, Z to cathode
C. X to cathode, Y stationary, Z to anode
D. X and Y to anode, Z to cathode

Answer

To determine the direction in which each amino acid (X, Y, and Z) will move during electrophoresis at pH 7.7, we need to analyze their pH values and how they relate to their charge at that pH.

### Step-by-Step Solution:

1. **Understanding the Charge of Amino Acids:**
- Amino acids have both an amino group (-NH2) and a carboxyl group (-COOH). The charge of an amino acid depends on the pH of the solution relative to its isoelectric point (pI).
- At a pH lower than its pI, the amino acid will be positively charged (due to the protonation of the amino group).
- At a pH higher than its pI, the amino acid will be negatively charged (due to the deprotonation of the carboxyl group).

2. **Analyzing Each Amino Acid:**
- **Amino Acid X (pH = 3.2):**
- Since 3.2 is acidic, at pH 7.7, which is higher than 3.2, X will be negatively charged.

- **Amino Acid Y (pH = 5.7):**
- Similar to X, since 5.7 is also acidic, at pH 7.7, Y will also be negatively charged.

- **Amino Acid Z (pH = 9.7):**
- Since 9.7 is basic, at pH 7.7, which is lower than 9.7, Z will be positively charged.

3. **Direction of Movement in Electrophoresis:**
- In electrophoresis, negatively charged particles move towards the anode (positive electrode), while positively charged particles move towards the cathode (negative electrode).
- Therefore:
- **X (negatively charged)** will move towards the anode.
- **Y (negatively charged)** will also move towards the anode.
- **Z (positively charged)** will move towards the cathode.

4. **Final Conclusion:**
- The movement of the amino acids under electrophoresis at pH 7.7 will be:
- X and Y will move towards the anode.
- Z will move towards the cathode.

### Summary of Movement:
- **X → Anode**
- **Y → Anode**
- **Z → Cathode**