#Question id: 53
#Unit 1. Molecules and their Interaction Relevant to Biology
Calculate the number of times the DNA of a modern E. coli cell has been copied accurately since its earliest bacterial precursor cell arose about 3.5 billion years ago. Assume for simplicity that over this time period, E. coli has undergone, on average, one cell division every 12 hours (this is an overestimate for modern bacteria, but probably an underestimate for ancient bacteria).
#Question id: 17674
#Unit 8. Inheritance Biology
#Question id: 10800
#Unit 6. System Physiology – Plant
Which of the following secondary metabolites causes infertility in the
#Question id: 13165
#Unit 5. Developmental Biology
#Question id: 3818
#Unit 3. Fundamental Processes
DNA replication is studied in a newly discovered bacterium. It takes 30 min for the bacterium to complete a round of replication at 37oC. A Meselson-Stahl-type experiment was performed. The bacteria were grown for several generations in 14N-medium and then switched to 15N-medium. The DNA molecules were then analyzed.
If the mechanism of DNA replication in this bacterium were semi-conservative, what results would be found when the double-stranded DNA was analyzed in a CsCl density gradient after three generations in 15N-medium?