# Explain why the offspring produced by cloning a mammal using somatic cell nuclear transfer are not completely identical to the donor animal that provided the diploid nucleus.

> Pearson Edexcel International GCSE Biology (4BI1) — 5.4 Cloning · Explain · 4 marks

> Dolly the sheep was the first mammal to be cloned from an adult somatic cell. A diploid nucleus from the udder cell of one ewe was inserted into an enucleated egg cell from a different ewe before being implanted into a surrogate mother.

## Mark scheme (4 marks)

1. The enucleated egg cell retains its own mitochondria / mitochondrial DNA
2. The mitochondria / mitochondrial DNA in the egg cell cytoplasm come from a different individual (the egg donor)
3. The surrogate mother / environment influences gene expression / phenotype of the clone
4. Therefore the clone has a slightly different genetic make-up / is not 100% genetically identical to the nucleus donor

## Key terms

- [cloning](https://www.gradenine.co.uk/glossary/cloning)
- [diploid nucleus](https://www.gradenine.co.uk/glossary/diploid-nucleus)
- [somatic cell nuclear transfer](https://www.gradenine.co.uk/glossary/somatic-cell-nuclear-transfer)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-offspring-produced-by-9c9fe154) · Published by Druglandscape Ltd.