Imagine It Is the Year 2050

Essay

Imagine it is the year 2050.Because the Martian landers discovered that liquid water was present on Mars,another probe was sent to look for signs of life.Cells containing double-stranded DNA were found,and using an automated variant of the Meselson-Stahl experiment,the original DNA was labeled with ¹⁴N and then transferred to ¹⁵N (note that this is the reverse of the original M-S experiment).In the low temperatures of Mars,the replication machinery works slower,so each cell division takes 60 hours.

Assume you do not know if replication machinery uses a dispersive,conservative,or semiconservative approach.Predict what the centrifuge tube patterns should be at 60,120,180,and 240 hours.