Question

Arrange the steps of recombinant DNA-cloning procedure in correct sequence of their occurance:
A. Joining the target DNA with cloning vector DNA by ligase enzyme.
B. Targeted DNA from a source organism is cleaved and cloning vector DNA is also cleaved by the same restriction endonuclease.
C. Selection of transformants from non-transformants through antibiotic resistance and color indicators
D. Introduction of recombinant DNA into host cell.
Choose the correct answer from the options given below:

• A. A, B, C, D
• B. A, C, B, D
• C. B, A, D, C
• D. C, B, D, A

Hint:

Think of it like building with LEGOs: 1. Get the right pieces and make sure they fit (Cut with restriction enzyme - B). 2. Stick them together (Ligate - A). 3. Put your creation into a display case (Transform into host cell - D). 4. Find your specific creation among many others (Select - C).

Answer 1

The Correct Option is C

Step 1: Concept Overview:
Recombinant DNA technology combines DNA from different sources to create new molecules. This question requires arranging the steps of a standard gene cloning experiment in the correct order.
Step 2: Step-by-Step Breakdown:
Here's the logical order of the steps:


Step B: DNA fragment preparation is the initial step. Both the target DNA (gene of interest) and the cloning vector (e.g., plasmid) are cut using the same restriction enzyme to create compatible ends.

Step A: The prepared target DNA fragment is then joined to the cut vector DNA using DNA ligase, forming the recombinant DNA molecule.

Step D: The recombinant DNA is introduced into a host organism, typically E. coli, via a process called transformation.

Step C: Because transformation is inefficient, cells containing the recombinant DNA (transformants) must be selected from non-transformed cells. Selectable markers like antibiotic resistance or blue-white screening are used for this purpose.

Step 3: Conclusion:
The correct order is B \(\rightarrow\) A \(\rightarrow\) D \(\rightarrow\) C.