Question

1. cation of a viral DNA genome that is An in vitro system is used to study circle. The location of the sites for the restriction names for each Mbol fragment are shown in Figure 1. Replication reactions are carried out using viral DNA as a template, extracts of infected cells as a souroe of enzymes, and dNTPs, all of which are labeled with 32P. The reaction products are digested with Mbol, analyzed by agarose gel electrophoresis, and visualized by a The same reaction is carried out in the presence of increasing concentrations of nonradioactive 2',3 dideoxyGTP (ddGTP), and the results are shown in lanes 2-4 in Figure 2. The origin of replication of this viral DNA is which Mbol fragment? Mbol on this DNA and the letter producing the results shown in lane 1 of Figure 2. Mbol p Mbol Mbol E Mbol Mbol 2 [ddGTP] 4 Figure 2

Is it C because the fragment is present in every reaction? Please explain.

Answer 1

Ans: C

As you expected the answer is C. Because since we are supplimenting the ddGTP it will results in the replication termination (lack of 3'OH). As you keep on increasing the concemtration of ddGTP it will retard the replication and results in the amplification of only the fragment near to origin of replication. So the lane having the band at higher con. of ddGTP will be having the origin of replication.