BIO372H5 Lecture Notes - Lecture 6: Okazaki Fragments, Semiconservative Replication, Deoxyribonuclease
Document Summary
Red is new dna, blue is old dna. Separation of dnas of different density by cscl density gradient centrifugation. Analytical approach - they note position of dna in the float. Meselson and stahl experiment to distinguish among the three hypothesis. They labeled e. coli dna with n14 and 15 - if we have heavy n, dna will be heavier. We watch dna to be lighter over time. Cscl gradient ultracentrifugation determines the density of the dna. Completely unlabeled = red (light dna) in 2nd line - will be more intense, blue will be less intense. Conservative - we end up with light dna, no heavy dna left. Dispersive - the ii mixed will be positioned in between light and heavy dna. The cells are in synthesis phase, some are later some are earlier. This is an average value, about 20 min to divide cell which is too big. Dispersive goes down (which means it doesn"t happen)
