Reproduction in Animals - Cloning

 CLONING

What is cloning ?
What is a clone ?
Dolly sheep ?

Reproduction involves different types, among them one of them is cloning.

Cloning is the production of an exact copy of an animal by means of asexual reproduction.  Animals which contain exactly the same genes are called genetically identical .An animal which is genetically identical to its parent is called a clone. A clone  is an exact copy of its parent. The cloning of a large animal was successfully done for the first time by fan Wilmut and his colleagues at the Roslin Institute in Edinburgh (Scotland) .They cloned a sheep named Dolly from its parent sheep called Finn Dorest sheep (a female sheep)  Dolly (the cloned sheep) was born on 5th July, 1996. Dolly the  sheep was the first mammal to be cloned.

Process of cloning

The cloning of animals is a special kind of asexual reproduction method. The cloning in animals is done by the transfer of nucleus of a cell. This happens as follows:
The nucleus of a normal body cell of the animal (which we wish to clone) is
transferred into an empty egg cell (whose nucleus has been removed). The newly formed egg cell is allowed to develop normally. An exact copy of the animal
(or a clone) is Let us know Dolly sheep in detail, we should know the meaning of the term "ewe. Ewe is a female sheep. The two sheep which were involved in the cloning of Dolly sheep were Finn Dorset ewe and Scottish Blackface ewe. We can  call them female Finn Dorset sheep and female Scottish Blackface sheep. As the name suggests, the Scottish Blackface sheep-has a black face. Keeping these terms in mind, we will now know about the cloning of Dolly' sheep from Finn Dorset ewe.

Dolly sheep

Cloning of 'Dolly Sheep

The Dolly sheep was cloned in the following way:

(1) A normal body cell was removed from the mammary gland of a female Finn Dorset sheep (which was to be cloned)
. (ii) An unfertilised egg cell was taken from a female Scottish Blackface sheep and its nucleus (containing chromosomes) was removed, leaving the egg cell empty (having no nucleus)

The nucleus of normal body cell of the Finn Dorset sheep was inserted into the empty egg cell of Scottish Blackface sheep. In this way a new egg cell was obtained (which had the nucleus of Finn Dorset sheep body cell).


 The new egg cell was implanted in the steros of another female Scottish Blackface sheep making it pregnant. After 148 days,  pregnant Scottish Blackface sheep gave birth to the  Dolly sheep .

Though Dolly sheep was given birth by a Scottish Blackface sheep it was found to be exactly identical to the original Finn Dorset sheep from whose cell nucleus was taken. So. Dolly was a clone of Finn Dorset sheep whose 'cell males was used in developing it All the body cells of Dolly sheep contained the same set of chronomes having exactly the same genes the Fino Borset sheep cells. So, though Dolly was birth by a Scottish Blackface sheep but its real mother was Fino Doeset sheep. Since the not show any characteristic features of the Scottish Blackface sheep For example, the

Scottish Blackface sheep had a blackface but Dolly sheep did not have a blackfac Dolly was a clone of Finn Dorset sheep and produced several offsprings of her own through sexual means in due course of time, Dolly had exactly the same genètic material as her real mother Finn Dorset sheep, Dolly died on 14th February 2003 due to a lung disease.

Since Dolly, the cloned sheep, who was bom in 1996, cows (and pigs) have been cloned. The cloning of superior cows which give high milk yield has become possible now. If a high milk yielding cow was to be mated with a bull for reproduction, then the resulting offspring cow may or may not be of high milk yielding breed (because of interniixing of genes of the parent bull and mother cow). On the other hand, a cow which is cloned from a parent cow of high milk yield will be an identical copy of the parent cow and hence give high milk yield.

Advantages of Cloning

The technique of cloning enables us to produce exactly identical copies of domestic animals having favourable characteristics (without the risk of losing some of the beneficial genes or introducing unwanted genes through sexual reproduction methods) Cloning produces identical copies of the parent domestic animals and helps in preserving desirable features (like high milk yield or good quality wool) of the parent animal for future generations. For example:

a cow which gives high milk yield can be cloned to produce exactly identical cows which will give high milk yield, and a sheep which gives high yield of superior quality wool can be closed to produce exactly identical sheep which will give high yield of superior quality wool.

The cloning of mammals also has some disadvantages. Many cloned mammals die before birth or die soon after birth. Many times, the cloned mammals are found to be born with severe abnormalities.