Question

Which of the following describes how Dolly (a cloned sheep) was created?

A. A mammary cell was made totipotent by treating it with hormones.
B. A mammary cell had its nucleus removed and the nucleus from an oocyte was inserted into it.
C. A mammary cell was fused with an egg cell that had its nucleus removed.
D. A sperm and egg cell were fused with a mammary cell that had its nucleus removed.

Answer 1

Dolly the cloned sheep was created through a process called somatic cell nuclear transfer (SCNT), where a mammary cell's nucleus was fused with an enucleated egg cell and subsequently implanted in a surrogate mother.

Step-by-step explanation:

Dolly, the cloned sheep, was created using the following method: C. A mammary cell was fused with an egg cell that had its nucleus removed.

To clone Dolly, a process known as somatic cell nuclear transfer (SCNT) was utilized. This procedure involved several steps:

• A somatic mammary cell from the adult sheep intended to be cloned was taken.
• The nucleus of this mammary cell, which contains the genetic material necessary to produce a clone, was isolated.
• Simultaneously, an egg cell from a donor sheep had its nucleus removed, resulting in an enucleated egg.
• The nucleus from the mammary cell was then introduced into the enucleated egg.
• The fused cell was stimulated with an electric shock to begin dividing, similar to a natural embryo development process.
• After reaching the blastocyst stage, the developing embryo was implanted into a surrogate mother sheep, where it continued to develop until birth.

This technique did not involve the traditional fusion of sperm and egg cells but instead replaced the egg cell's genetic material with that from a somatic cell to initiate embryonic development.