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: Understanding the Concept:
Recombinant DNA technology involves creating a new DNA molecule by combining genetic material from different sources. The question asks for the logical sequence of steps in a standard gene cloning experiment.
Step 2: Detailed Explanation:
Let's arrange the steps logically:


Step B: First, you must prepare the DNA fragments. This involves cutting both the target DNA (gene of interest) and the cloning vector (e.g., a plasmid) with the same restriction enzyme to generate compatible ends.

Step A: Next, the prepared target DNA fragment is joined with the cleaved vector DNA. The enzyme DNA ligase is used to form phosphodiester bonds, creating the recombinant DNA molecule.

Step D: The newly created recombinant DNA must be introduced into a host organism, usually a bacterium like E. coli. This process is called transformation.

Step C: Transformation is an inefficient process, so you need to select the few cells that successfully took up the recombinant DNA (transformants) from the vast majority that did not. This is done using selectable markers like antibiotic resistance or color indicators (e.g., blue-white screening).

Step 3: Final Answer:
The correct sequence of occurrence is B \(\rightarrow\) A \(\rightarrow\) D \(\rightarrow\) C.