Question

Dolly sheep cloned by Dr.Ian Wilmut was genetically identical to
(a) The donor sheep which donated diploid nucleus
(b) The sheep which donated the egg cell
(c) The surrogate mother
(d) The sheep which donated haploid nucleus

Answer 1

Dolly was the first sheep to be cloned successfully after 276 failed attempts by Dr.Ian Wilmut and his colleagues at Roslin Institute in Edinburgh. It happened in 1996 and it revolutionized the way people thought about the concept of cloning.

Complete Answer:
Cloning is defined as the process of making a genetically identical organism by the means of a non-sexual method. Such an offspring is known as a clone. Natural cloning occurs in plants and is known as vegetative reproduction. For example, a runner of a strawberry structure produces identical clones of it and thus is a naturally occurring cloning method. Dolly was cloned artificially by humans through a nuclear transfer procedure. This was done by fusing a nucleus from Finn Dorsett sheep with an enucleated egg of Scottish blackface ewe. Since the nucleus was taken from Finn Dorsett sheep, Dolly was genetically identical to this sheep.

Additional information: Let us look in detail as to how Dolly was cloned.
- Wilmut and his colleagues took a nucleus from the mammary gland cell of a Finn Dorsett sheep and fused it with the enucleated egg cell of a Scottish blackface ewe.
- The nucleus-egg combination was made to fuse and then divide with the help of electrical stimulation.
- The new cell was divided and was placed in the uterus of a blackface ewe as a surrogate. Dolly was born months later.
- Dolly grew into an adult and produced offspring through natural reproduction which indicates that she is a healthy clone.
So, the correct option is ‘(a) The donor sheep which donated diploid nucleus’.

Note:
- Dolly is also the first mammal to be cloned.
- A great application of cloning is that it can be used to save endangered species that have a slow reproduction rate to increase their numbers efficiently.
- Crops have been produced for many years by the process of cloning known as tissue culture and it utilizes the property of totipotency found in plants.
- Totipotency is the ability of a plant to become a fully developed adult from a small piece i.e. every part of the plant can become fully grown if provided with proper conditions.