Question

What is the correct sequence of steps in the genetic engineering of {E.coli for insulin production?
A. Obtaining a copy of the human insulin gene by isolating mRNA
B. Switching on gene action.
C. Identifying transformed bacteria prior to cloning
D. Inserting the DNA into a plasmid vector and inserting the plasmid vector into the host bacterium}
Choose the most appropriate answer from the options given below:

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

Hint:

Think of the process like a recipe:

\textbf{Get the gene} (Isolate the recipe - Step A).
\textbf{Put the gene in a carrier and get it into the factory} (Put the recipe in a cookbook and give it to the chef - Step D).
\textbf{Find the factory that accepted the gene} (Make sure the chef got the right cookbook - Step C).
\textbf{Tell the factory to start producing} (Tell the chef to start cooking - Step B).

Answer 1

The Correct Option is C

Step 1: Concept Summary:
This question tests the correct order of steps to produce human insulin in *E. coli* using recombinant DNA technology.

Step 2: Step-by-Step Explanation:
1. A. Obtain human insulin gene copy via mRNA isolation: The initial step involves isolating the human insulin gene. Typically, mRNA from pancreatic cells is isolated and reverse transcriptase is used to generate a complementary DNA (cDNA) copy. cDNA is preferred because it lacks introns, which bacteria cannot process.
2. D. Insert DNA into plasmid, then plasmid into bacteria: The insulin gene (cDNA) is then inserted (ligated) into a plasmid vector. This recombinant plasmid is introduced into *E. coli* via transformation.
3. C. Identify transformed bacteria before cloning: Transformation isn't perfectly efficient. Identifying bacteria containing the recombinant plasmid is crucial. Selectable markers, like antibiotic resistance genes on the plasmid, are used. Only transformed bacteria survive on antibiotic-containing media.
4. B. Activate gene expression: After selection, transformed bacteria are cultured to increase their numbers (cloned). Insulin production requires inducing ("switching on") the inserted gene's expression, often controlled by an inducible promoter activated by a chemical (e.g., IPTG).

Step 3: Answer:
The correct sequence for recombinant insulin production is A \(\rightarrow\) D \(\rightarrow\) C \(\rightarrow\) B.