#Question id: 3815
#Unit 3. Fundamental Processes
Use the figure to answer the following question. A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in the figure would you expect if the DNA was replicated in a conservative manner?
#Question id: 3816
#Unit 3. Fundamental Processes
The mechanism of DNA replication is studied in an E. coli replication fork. Which is a characteristic of an E. coli replication fork and a eukaryotic replication fork?
#Question id: 3817
#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 dispersive, what results would be found when the double-stranded DNA was analyzed in a CsCl gradient after two generations in 15N-medium?
#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?
#Question id: 3819
#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.
After one generation in 15N-medium, the DNA is denatured and analyzed in a CsCl gradient. If the single-stranded DNA forms two bands, one with heavy density and one with light density, what conclusion could be drawn about the mechanism of DNA replication in this bacterium?
#Question id: 3820
#Unit 3. Fundamental Processes
Meselson and Stahlʹs experiments involved growing E. coli on a medium containing 15N (heavy nitrogen) which increased the density of the bacterial DNA. Cells were then grown on a medium containing only 14N. DNA samples were obtained for analysis after one, two and three rounds of replication (generations) and centrifuged on a density gradient. The double-helical DNA forms bands in the gradient depending on its density. How many bands did Meselson and Stahl see after two generation of cells were grown on the 14N medium?