Biochemistry 4th Edition by Christopher Mathews,Kensal van Holde, Dean Appling, Spencer Anthony Cahill

تمرين 4

A mixture of four -[ 32 P]-labeled ribonucleoside triphosphates was added to permeabilized bacterial cells undergoing DNA replication, and incorporation into high-molecular-weight material was followed over time, as shown in the accompanying graph. After 10 minutes of incubation a 1000-fold excess of unlabeled ribonucleoside triphosphates was added, with the results shown in the graph.
(a) Why was the excess of unlabeled rNTPs added
(b) How could you tell that radioactivity is being incorporated as ribonucleotides, rather than an alternative such as reduction deoxyribonucleotides, followed by incorporation
(c) What does this experiment tell you about the process of DNA replication