With reference to the cloning of the sheep 'Dolly', which one of the following statements is correct?

Correct Option

The correct option is

It involved the production of an exact genetic copy of a living organism.

Explanation

Cloning is the process of producing individuals with identical or virtually identical DNA, either naturally or artificially. In biotechnology, reproductive cloning refers to the creation of an animal that has the same nuclear DNA as another currently or previously existing animal. The most common technique used is Somatic Cell Nuclear Transfer (SCNT).

Statement-wise Analysis

• Statement It involved the production of an exact genetic copy of a living organism.: Correct. Cloning involves the production of an exact genetic copy of a living organism. In the case of 'Dolly' the sheep (born in 1996), the nucleus from an adult somatic cell (udder cell) was transferred into an enucleated egg cell, creating a sheep genetically identical to the donor of the somatic cell.
• Statement It resulted in an animal that was immune to all diseases.: Incorrect. Cloning does not confer immunity to diseases. A clone has the same genetic makeup as the donor, meaning it shares the same genetic susceptibilities. Dolly, for instance, suffered from arthritis and lung disease, similar to other sheep.
• Statement It was the first successful cloning of an amphibian.: Incorrect. Dolly was not the first cloned amphibian; amphibians (such as frogs) were successfully cloned in the 1950s (e.g., by Briggs and King in 1952). Dolly’s significance lies in being the first mammal to be cloned successfully from an adult somatic cell.
• Statement It was produced through the fusion of sperm and egg in a test tube.: Incorrect. The fusion of sperm and egg describes sexual reproduction or In Vitro Fertilization (IVF). Dolly was produced asexually via SCNT, where a somatic cell nucleus was fused with an egg cell that had its nucleus removed, without the involvement of sperm.

Key Takeaway

Dolly the Sheep was the first mammal cloned from an adult somatic cell using the Somatic Cell Nuclear Transfer (SCNT) technique, resulting in an organism genetically identical to the donor.