Question

Choose correct statements about two-dimensional electrophoresis. A. It is a combination of IEF and SDS-PAGE.
B. It separates proteins of identical molecular weight that differ in pI.
C. It can't separate proteins with similar pI values but differ in molecular weight.
D. Thousands of cellular proteins can be resolved with this technique.
E. Microscopy can be used to identify individual protein spots in IEF.
Choose the correct answer from the options given below :

• A. \(B, C\) only
• B. \(A, C, E\) only
• C. \(A, B, D\) only
• D. \(C, D\) only

Hint:

Remember: \[ \text{2D Electrophoresis} = \text{IEF} + \text{SDS-PAGE} \]
• First dimension \(\rightarrow\) Separation by \(pI\)
• Second dimension \(\rightarrow\) Separation by molecular weight \[ \text{Widely used in proteomics studies} \]

Answer 1

The Correct Option is C

Concept: Two-dimensional gel electrophoresis (2D electrophoresis) is a powerful protein separation technique that separates proteins based on:
• Isoelectric point (\(pI\))
• Molecular weight The two dimensions are:
• First dimension: Isoelectric focusing (IEF)
• Second dimension: SDS-PAGE This technique is widely used in: \[ \text{Proteomics} \]

Step 1: Evaluating statement A. Statement A: \[ \text{2D electrophoresis combines IEF and SDS-PAGE} \] This is correct. Proteins are first separated by: \[ pI \] and then by: \[ \text{Molecular weight} \] Thus: \[ \boxed{A \text{ is correct}} \]

Step 2: Evaluating statement B. Statement B: \[ \text{It separates proteins with same molecular weight but different } pI \] This is correct because IEF separates proteins according to isoelectric point. Thus: \[ \boxed{B \text{ is correct}} \]

Step 3: Evaluating statement C. Statement C: \[ \text{It cannot separate proteins with similar } pI \text{ but different molecular weight} \] This is incorrect. Even if proteins have similar: \[ pI \] they can still be separated in the second dimension using: \[ \text{SDS-PAGE} \] based on molecular weight. Thus: \[ \boxed{C \text{ is incorrect}} \]

Step 4: Evaluating statement D. Statement D: \[ \text{Thousands of cellular proteins can be resolved} \] This is correct. 2D electrophoresis has high resolving power and is extensively used for large-scale protein analysis. Thus: \[ \boxed{D \text{ is correct}} \]

Step 5: Evaluating statement E. Statement E: \[ \text{Microscopy can identify individual protein spots in IEF} \] This is incorrect. Protein spots are generally visualized using:
• Coomassie staining
• Silver staining
• Fluorescent dyes rather than microscopy. Thus: \[ \boxed{E \text{ is incorrect}} \] Therefore, the correct statements are: \[ \boxed{A, B, D} \] Hence, the correct answer is: \[ \boxed{(C)\ A, B, D \text{ only}} \]