Question

plasmid dna samples are taken from four bacteria species and treated with the same restriction enzyme. the treated dna is then analyzed using gel electrophoresis. the results of the gel electrophoresis are shown in the diagram.
gel electrophoresis results

which species has the most restriction enzyme recognition sites in its dna?
(a) species 1
(b) species 2
(c) species 3
(d) species 4

Explanation:

Restriction enzymes cut DNA at specific recognition sites; more cuts produce more DNA fragments visible on the gel. Counting fragments: Species 1 has 2, Species 2 has 2, Species 3 has 5, Species 4 has 4. More fragments mean more recognition sites.

Answer:

C. species 3