SCIENTIFIC THINKING Each scientist works as part of a broader community of scientists, building on the work of others. Scientific advances often depend on the application of new technologies and/or on new techniques applied to an existing problem. What improvements to existing cloning methods did Wilmut make that allowed him to successfully clone Dolly the sheep from an adult cell?

Verified step by step guidance

1. Understand the context of cloning: Cloning involves creating a genetically identical copy of an organism. In the case of Dolly the sheep, the process used was somatic cell nuclear transfer (SCNT), which involves transferring the nucleus of a somatic (body) cell into an enucleated egg cell.
2. Recognize the challenge Wilmut addressed: Previous cloning attempts often used embryonic cells, which are more flexible and easier to reprogram. Wilmut's breakthrough was successfully cloning an organism using the nucleus from an adult somatic cell, which is more specialized and harder to reprogram.
3. Identify the key improvement: Wilmut and his team introduced a critical step of 'cell cycle synchronization.' They starved the donor somatic cells to induce them into a quiescent state (G0 phase of the cell cycle). This synchronization made the nucleus more receptive to reprogramming when transferred into the enucleated egg cell.
4. Understand the reprogramming process: After transferring the adult somatic cell nucleus into the enucleated egg, the egg was stimulated using electrical pulses to mimic fertilization. This step initiated the reprogramming of the adult nucleus to behave like a zygote nucleus, capable of directing embryonic development.
5. Recognize the significance: Wilmut's method demonstrated that adult somatic cells could be reprogrammed to create a viable clone, paving the way for advancements in cloning technology and raising important ethical and scientific questions about the potential applications of cloning.

Key Concepts

Somatic Cell Nuclear Transfer (SCNT)

Somatic Cell Nuclear Transfer is a cloning technique where the nucleus of a somatic cell is transferred into an enucleated egg cell. This process allows the egg to develop into an organism that is genetically identical to the donor of the somatic cell. Wilmut's successful cloning of Dolly the sheep utilized SCNT, which was pivotal in demonstrating that adult cells could be reprogrammed to develop into a new organism.

Reprogramming of Adult Cells

Reprogramming refers to the process of reverting differentiated adult cells back to a pluripotent state, allowing them to develop into any cell type. Wilmut improved existing cloning methods by effectively reprogramming the adult somatic cell nucleus, which was crucial for overcoming the limitations of previous cloning attempts that primarily used embryonic cells.

Epigenetic Modifications

Epigenetic modifications are chemical changes to DNA and histone proteins that affect gene expression without altering the underlying DNA sequence. These modifications play a significant role in cellular differentiation and development. Wilmut's advancements in cloning involved understanding and manipulating these epigenetic factors to ensure that the cloned embryo developed properly, reflecting the characteristics of the adult donor.