Question

Student to attempt either option (A) or (B): (A) How is DNA isolated in purified form from a bacterial cell?
OR
(B) Explain how human functional insulin was produced by using recombinant DNA (rDNA) technology.

Hint:

DNA isolation uses enzymes and alcohol for purification. Insulin production via rDNA involves expressing and joining A and B chains in bacteria.

Answer 1

(A) Step 1: Bacterial cells are lysed using enzymes such as lysozyme to break the cell wall.
Step 2: Detergents like SDS (sodium dodecyl sulfate) are used to break open cell membranes and release cellular contents. 
Step 3: Proteins and RNA are removed by treatment with protease and RNase enzymes respectively. 
Step 4: The purified DNA is then precipitated by adding chilled ethanol or isopropanol. 
OR 
(B) Step 1: DNA sequences encoding the insulin A and B chains were isolated and inserted into plasmids. 
Step 2: These recombinant plasmids were introduced into E. coli bacteria. 
Step 3: The bacteria produced the A and B chains separately. 
Step 4: These chains were extracted and chemically joined to form functional human insulin.