# Scientists have developed a genetically engineered goat that produces a human protein called antithrombin in its milk. Antithrombin is used to treat patients whose blood clots dangerously. Explain how genetic engineering could be used to produce a goat that makes human antithrombin in its milk.

> OCR A-Level Biology B — Advancing Biology (H422) — 5.3 Manipulating genomes · Explain · 5 marks

> Antithrombin is a human protein that prevents dangerous blood clotting. It is normally produced in human liver cells. Scientists wanted to produce large quantities of antithrombin cheaply, so they genetically engineered goats to secrete the protein in their milk.

## Mark scheme (5 marks)

1. The human gene that codes for antithrombin is identified and cut out / isolated from human DNA
2. A vector (such as a plasmid) is used to carry the human gene
3. The vector / gene is introduced into a goat embryo cell / fertilised egg cell at an early stage
4. The human gene becomes part of the goat's genome / is incorporated into the goat's DNA
5. The goat expresses the human gene and produces / secretes antithrombin in its milk, which can then be collected

## Key terms

- [gene](https://www.gradenine.co.uk/glossary/gene)
- [genetic engineering](https://www.gradenine.co.uk/glossary/genetic-engineering)

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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/scientists-have-developed-a-genetically-engineered-c31517e9) · Published by Druglandscape Ltd.