Question

Dolly sheep was genetically similar to
A) The mother from which enucleated egg cell was taken
B) The mother from which nucleated udder cell was taken
C) The surrogate mother
D) Both surrogate mother and the donor mother

Answer 1

Hint: Dolly the sheep was the first mammal to be cloned. A clone has the same DNA sequence as its parent and so they are genetically identical to their parents.

Complete answer:
DNA cloning is a method by which genetically similar or clones of a particular gene or DNA is made under laboratory conditions. Let us analyse the options to find the correct answer.

Option A: Enucleation is the removal of the nuclear body of a cell. It involves the removal of all the information contained in the nuclear cell. Genetic information is present in the nuclear cell. This process is used in cloning but it was not used in the production of Dolly sheep. Hence, option A is incorrect.
Option B: For the production of Dolly an udder cell from six year old Finn Dorset white sheep was used. The scientists reprogrammed the udder cells by altering the growth medium. Then they fused the nucleus from an adult white sheep cell with the egg cell from the black faced sheep. They cultured it for six to seven days before implanting into the surrogate mother. Hence, option B is correct.
Option C: Surrogacy is an legal approved agreement where the woman agrees to bear the child of a person or person’s who will become the parents after the birth of the child. Surrogate mother is only used for the implantation. Hence, option C is incorrect.
Option D: The surrogate mother was used for the implantation and the donor mother was used for the fertilization. Hence, option D is incorrect.

Thus, the correct answer is option (B) The mother from which the nucleated udder cell was taken.

Note: Dolly the sheep was made using the technique known as DNA cloning. The importance of this technique is as follows,
i) It can help in analysis of the effect of mutation of a particular gene.
ii) It can be used to develop non - functional genes in order to understand the functioning of normal genes.
iii) It can be used to make proteins like insulin.