Video Transcript
The two sheep in the figure shown
were used in a somatic cell nuclear transfer procedure. Eggs were obtained from sheep 1,
and skin cells were obtained from sheep 2. What would the genetic makeup of
the offspring produced by this process be? (A) The offspring would be
genetically identical to sheep 1. (B) The offspring would be
completely white in color. (C) The offspring would be
genetically identical to sheep 2. (D) The offspring would be
genetically different to sheep 1 and sheep 2. Or (E) the offspring would be
completely black in color.
This question asks us about a
procedure called somatic cell nuclear transfer. So, what is this procedure and how
does it work? Somatic cell nuclear transfer, also
called renucleation, is a form of artificial reproduction, which is the creation of
new life in ways that are not natural. It is a technique that can be used
to produce genetically identical copies of animals or clones. There are multiple steps in this
process. Let’s remove our answer choices for
now so we have more space to go over the stages in the process in the context of
this question.
First, the nucleus is removed from
a skin cell that has been obtained from sheep 2. Then, the egg cell that has been
obtained from sheep 1 is enucleated. This means the nucleus is removed
from the cell. The skin cell nucleus from sheep 2
is inserted into the enucleated egg cell from sheep 1. The result is an embryo that can
then be transferred to a surrogate sheep, where it can implant and develop.
The lamb born as a result, sheep 3
in our diagram, will be genetically identical to sheep 2. This is because the genetic
material of a eukaryotic organism is found in the nucleus. The egg cell from sheep 1 now
contains the genetic information from sheep 2. The genetic information will
determine many of the characteristics and features of the offspring. So, we would expect the offspring
to share the physical features of sheep 2, for example, a white fleece and brown
face.
We now have enough information to
answer our question correctly. So, let’s bring back our answer
choices. The correct answer is (C). The offspring would be genetically
identical to sheep 2.