Question

Arrange the steps in cloning and expressing a gene in correct order :
A. Introduction of recombinant molecule into new host that expresses the gene
B. Use of restriction enzymes or PCR to generate fragments of DNA
C. Protein purification
D. Isolation of DNA to be cloned
E. Generation of a recombinant molecule by inserting DNA fragments into vectors
Choose the correct answer from the options given below :

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

Hint:

Remember the cloning workflow: \[ \text{Isolate DNA} \rightarrow \text{Cut/Amplify} \rightarrow \text{Ligate into Vector} \rightarrow \text{Transform Host} \rightarrow \text{Purify Protein} \]
• Restriction enzymes create compatible DNA ends.
• Vectors commonly used include plasmids and bacteriophages.

Answer 1

The Correct Option is A

Concept: Gene cloning and expression involve insertion of a desired gene into a suitable vector followed by introduction into a host organism for production of the desired protein. Major steps include:
• Isolation of DNA
• Preparation of DNA fragments
• Formation of recombinant DNA
• Transformation into host cells
• Expression and purification of protein

Step 1: Isolation of DNA to be cloned. The process begins with: \[ \text{Isolation of the desired DNA} \] Thus, the first step is: \[ \boxed{D} \]

Step 2: Generation of DNA fragments. The isolated DNA is then processed using:
• Restriction enzymes
• PCR amplification to obtain the desired gene fragment. Thus: \[ \boxed{B} \]

Step 3: Formation of recombinant DNA molecule. The DNA fragment is inserted into a cloning vector: \[ \boxed{E} \] forming a recombinant DNA molecule.

Step 4: Introduction into host cell. The recombinant molecule is introduced into a suitable host cell for gene expression. Thus: \[ \boxed{A} \]

Step 5: Protein purification. After expression of the cloned gene: \[ \text{Desired protein is purified} \] Thus: \[ \boxed{C} \] Therefore, the correct sequence is: \[ \boxed{D \rightarrow B \rightarrow E \rightarrow A \rightarrow C} \] Hence, the correct answer is: \[ \boxed{(A)\ D, B, E, A, C} \]