Question

A circular plasmid gives the illustrated pattern of bands when digested by a single (A, B, M) or in combination with up to three restriction enzymes, available (A), BglII (B), and MboI (M). Draw a restriction map of the plasmid. (2 pts)

a. True
b. False

Answer 1

Restriction enzymes cut specific DNA sequences to defend bacteria against foreign DNA; they are also critical in the creation of recombinant DNA. Antibiotic resistance and reporter genes in plasmid vectors facilitate the selection and identification of successful transformations in molecular cloning. Restriction mapping and RFLP analysis employ restriction enzyme digestion and electrophoresis for creating and comparing DNA banding patterns.

Step-by-step explanation:

The original function of a restriction enzyme is to recognize specific DNA sequences and cut them in a predictable manner. This system essentially acts as a bacterial defense mechanism against foreign DNA. Many restriction enzymes create staggered cuts that produce DNA fragments with overhangs, which can be used to create recombinant DNA by attaching to complementary overhangs from other DNA molecules.

Recombinant DNA can be introduced into bacterial host cells through two main processes: transformation and ligation. In a molecular cloning approach using plasmids as vectors, the plasmid contains both an antibiotic resistance gene and a reporter gene. The antibiotic resistance gene allows for the selection of successful transformants (bacteria that have taken up the plasmid), while the reporter gene, such as one encoding for the B-galactosidase enzyme, can help identify whether the plasmid within the bacterium is recombinant.

In the context of agarose gel electrophoresis, a circular plasmid may travel differently than linear DNA due to its conformation. Restriction mapping and RFLP analysis are techniques that utilize restriction enzyme digestion followed by agarose gel electrophoresis to generate and compare DNA banding patterns.