Video Transcript
What are the products of
semiconservative DNA replication? (A) Four single-stranded molecules
of DNA that are identical to each other and to the original DNA molecule. (B) Two double-stranded molecules
of DNA that are identical to each other and to the original DNA molecule. (C) Two single-stranded molecules
of DNA, containing half of the DNA of the original DNA molecule. (D) Four double-stranded molecules
of DNA that are all genetically unique.
In order to answer this question,
let’s go over some of the key terms. DNA is a double-stranded molecule
that carries the genetic information in the cells of living organisms. It is responsible for controlling
the activities of every cell in the organism’s body. When cells need to divide, they
need to provide a copy of DNA to each new cell so that they can perform the same
functions as the original cell. This is why DNA replication
happens, to provide each new cell with a complete copy of the genetic
information.
So, now that we know why DNA
replication is needed, we need to discuss what the word “semiconservative”
means. “Semiconservative” describes the
nature of DNA replication. A group of enzymes work together to
perform this process. When a molecule of DNA needs to
replicate, one enzyme unwinds the two strands to separate them, as we can see
here. Another enzyme then synthesizes two
new strands using the two original ones. In this way, each new
double-stranded DNA molecule contains one original DNA strand and one new DNA
strand. This is why the process is called
semiconservative DNA replication. The word semi- means half. Each new DNA molecule contains half
of the original one.
Now let’s think about the genetic
information that these strands carry. You might recall that the two
strands in a DNA molecule are complementary to one another. Each new synthesized strand will
therefore be complementary to the original strand. These complementary strands combine
with the original strands to make two identical molecules of DNA that are also
identical to the original double-stranded molecule.
Therefore, the option that best
describes the products of semiconservative DNA replication is given by answer choice
(B), two double-stranded molecules of DNA that are identical to each other and to
the original DNA molecule.
