In many bacteria, there is a single "bacterial chromosome." This is a circular piece of DNA that contains the genetic blueprint of the bacterium and, just as in eukaryotic cells, it has to be replicated and a copy passed to each daughter cell produced from cell division. These bacteria can be grown for many generations in culture medium containing 15N (Nitrogen15) until all of their DNA is labeled with 15N. One cell is removed from the 15N medium and is placed into medium in which all of the available nucleotides are labeled with 14N. The cell is allowed to replicate its DNA and divide four times, producing sixteen daughter cells. Which of the following is true? (For this question, a strand of DNA is defined as a single piece of DNA - i.e., a DNA double helix will have TWO strands of DNA in it).
a) All sixteen daughter cells will each contain two strands of 15N-labeled chromosomal DNA.
b) Eight of the daughter cells will each contain one strand of 14N-labeled DNA and the others will each contain one strand of 15N-labeled chromosomal DNA.
c) Two of the daughter cells will each contain two strands of 15N -labeled chromosomal DNA.
d) Two of the daughter cells will each contain one strand of 15N-labeled chromosomal DNA.
e) One of the daughter cells will contain two strands of 15N-labeled chromosomal DNA.