Question

You identify an RFLP in mice by digesting genomic DNA with HindIII enzyme and radiolabeling a piece of probe DNA. Southern blot analysis shows that the probe detects a 2-kb fragment in one strain of mice and a 4-kb fragment in another strain of mice. The two mice strains are crossed to produce an F1 generation. Two F1siblings are mated to produce a dozen F2 progeny. You isolate genomic DNA from several F1 and F2 individuals, digest with HindIII, and perform a Southern blot with the same probe.How many bands would be seen in the Southern blot of an F1 individual?A. twoB. fourC. one or twoD. oneE. three

Answer 1

Answer:

Part 1 =          (A) Two

Part 2 =         (B) Cleavage of X-gal

Explanation:

Part 1: As   probe detects a 2-Kb fragment in one strain of mice and a 4-kb fragment in another strain of mice.Thus 2 bands would be seen in the Southern blot of an F1 individual.

Part 2: The antibiotic & Xgal markers provide a selection scheme for recombinant bacterial colonies, as follows. First, only bacterial colonies that contain a plasmid-borne antibiotic-resistance gene can grow at all. Second, of those that grow, only those whose plasmids carry a functional LacZ in the poly-linker can metabolize Xgal.