Bacteria Are Grown in a Medium Containing ¹⁵NH₄Cl for a Number

Multiple Choice

Bacteria are grown in a medium containing ¹⁵NH₄Cl for a number of generations so that all of the DNA is made of fully "heavy" DNA.The bacteria are moved to a new medium and grown in ¹⁵NH₄Cl so that all new DNA will be light.After one generation time,what does the DNA look like?

A) All of the DNA is made of 2 "light" strands.
B) All of the DNA is made of 2 "heavy" strands.
C) All of the DNA is made of 1 "heavy" strand and 1 "light" strand.
D) Each strand is made of a mixture of "heavy" and "light" DNA,with each strand being between 75% and 100% "light".
E) Half of the DNA is made of 2 "light" strands and half of the DNA is made of 2 "heavy" strands.