Question

From the below list, which of the following is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?
(i) Transformbacteria with recombinant DNA molecule.
(ii) Cut the plasmid DNA using restriction enzymes.
(iii) Extract plasmid DNA from bacterial cells.
(iv) Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.
(v) Use ligase to seal plasmid DNA to nonplasmid DNA.

• A. (iv), (v), (i), (ii), (iii)
• B. (iii), (ii), (iv), (v), (i)
• C. (iii), (iv), (v), (i), (ii)
• D. (ii), (iii), (v), (iv), (i)

Answer 1

The correct option is B (iii), (ii), (iv), (v), (i)

1. A gene of interest ( DNA fragment) is isolated from cells that have been grown in laboratory culture.

2. Both the human DNA and the plasmid are treated with the same restriction enzyme to produce identical sticky ends.

3. The restriction enzyme cuts the plasmid DNA at its single recognition sequence, disrupting the antibiotic resistance gene.

4. The DNA fragment are mixed together and the complementary sticky ends are attached to each other by base pairing. The enzyme DNA- ligase is added to bond the sticky ends.

5. The recombinant plasmid or molecular clone, is introduced into a bacterial cell by adding the DNA to a bacterial culture. Under the right condition some bacteria will take up the plasmid from solution by the process transformation.

Therefore, the correct answer is option B.