Question

Arrange the steps of agarose gel electrophoresis in correct order :
A. Preparation of agarose gel
B. Visualization under UV light
C. Loading of DNA samples
D. Migration of DNA fragments
E. Application of electric current
Choose the correct answer from the options given below :

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

Hint:

Remember: \[ \text{Smaller DNA fragments migrate faster in agarose gel} \] Sequence of electrophoresis: \[ \text{Prepare Gel} \rightarrow \text{Load Sample} \rightarrow \text{Run Current} \rightarrow \text{Migration} \rightarrow \text{Visualization} \]
• DNA is visualized using UV light after staining.

Answer 1

The Correct Option is D

Concept: Agarose gel electrophoresis is a technique used to separate DNA fragments according to size. DNA molecules are negatively charged due to phosphate groups and therefore migrate toward the positive electrode in an electric field. Major steps include:
• Gel preparation
• Sample loading
• Application of electric field
• DNA migration
• Visualization of DNA bands

Step 1: Preparation of agarose gel. Initially: \[ \text{Agarose is dissolved in buffer and poured into a casting tray} \] to form the gel matrix. Thus, the first step is: \[ \boxed{A} \]

Step 2: Loading of DNA samples. After the gel solidifies: \[ \text{DNA samples are loaded into wells} \] Thus: \[ \boxed{C} \]

Step 3: Application of electric current. Electric current is then applied across the gel: \[ \boxed{E} \] This creates the electric field required for DNA movement.

Step 4: Migration of DNA fragments. DNA fragments migrate through the agarose matrix: \[ \boxed{D} \] Smaller fragments move faster and travel farther than larger fragments.

Step 5: Visualization under UV light. Finally: \[ \text{DNA bands are visualized under UV light} \] after staining with dyes such as ethidium bromide. Thus: \[ \boxed{B} \] Therefore, the correct sequence is: \[ \boxed{A \rightarrow C \rightarrow E \rightarrow D \rightarrow B} \] Hence, the correct answer is: \[ \boxed{(D)\ A, C, E, D, B} \]