Molecular Biology of the Gene 7th Edition by Richard Losick, James Watson, Michael Levine, Tamara Baker, Alexander Gann

Exercise 2

Review Box 9-1. Incorporation assays measure DNA synthesis using 32 P-labeled dNTPs (where 32 P replaces the ? phosphate of the dNTP).
A. If you use dNTPs labeled at the b or g phosphates, you do not detect any radioactivity in the newly synthesized DNA. Explain why.
B. Following incorporation of 32 P-labeled dNTPs, you must separate the unincorporated 32 P-labeled dNTPs from the newly synthesized DNA strand before measuring the amount of 32 P incorporation. Explain how gel electrophoresis serves as a means to separate unincorporated 32 P-labeled dNTPs from the newly synthesized DNA strand.
C. For the filter binding shown in Box 8-1 Figure 2, describe a negative control that would ensure that your filter is separating the unincorporated 32 P-labeled dNTPs from the DNA.