Question

What percentage composition of hybrid versus light DNA was observed in Generation 3 of the Meselson and Stahl experiment?

Options

• 37.5% hybrid and 62.5% light

• 50% hybrid and 50% light

• 25% hybrid and 75% light

• 12.5% hybrid and 87.5% light

Answer 1

In Generation 3, the two bands showed a composition of 25% hybrid DNA and 75% light DNA. This progressive decrease in the proportion of hybrid DNA with each generation is predicted by semi-conservative replication, as the single hybrid molecule from Generation 1 continues to be diluted by new light DNA molecules produced from the light strands in each successive replication cycle.