The question is incomplete. The complete question is:
A group of six students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in a particular gene of interest.
Analysis of the data obtained shows that two students each have two fragments, two students each have three fragments, and two students each have one only. What does this demonstrate?
A) Each pair of students has a different gene for this function.
B) The two students who have two fragments have one restriction site in this region.
C) The two students who have two fragments have two restriction sites within this gene.
D) The students with three fragments are said to have "fragile sites."
E) Each of these students is heterozygous for this gene.
Answer:
B) The two students who have two fragments have one restriction site in this region.
Explanation:
Restriction enzymes are the endonucleases that cut the DNA at specific sequences only. These sequences are called restriction sites. Each restriction enzyme has a unique restriction site at which it digests the DNA.
According to the given information, the students used a restriction enzyme that cut at zero, one, or two sites in a particular gene of interest. The presence of zero restriction sites in the gene for the restriction enzyme would not allow the enzyme to digest the DNA. On the other hand, the presence of one restriction site in the region would allow the restriction enzyme to make one cut in the DNA and formation of two restriction digestion DNA fragments.
