Video Transcript
Which of the following diagrams
most accurately demonstrates semiconservative DNA replication?
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 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
provide 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. Each new synthesized strand is
complementary to the original opposing strand. These complementary strands combine
with the original strand to make two identical double-stranded molecules of DNA that
are identical to the original double-stranded molecule we started with.
Getting back to our question, the
option that best illustrates semiconservative DNA replication is given by answer
choice (A).
