Cloned transgenic animals and human proteins

Use of biological resources · Cloning · note 3 of 3

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Cloned transgenic animals and human proteinsSpec 5.20B

In short

Cloned transgenic animals are animals, such as sheep or goats, that carry a human gene and are cloned to make many identical copies. They produce human proteins, often in their milk, where the protein is collected and purified. Examples are alpha-1-antitrypsin, used to treat emphysema, and blood clotting factors, used to treat haemophilia.

Animals can be made transgenic by adding a human gene to their cells. Cloning can then produce many identical animals that all carry that gene. These cloned transgenic animals can be used to produce human proteins.

The human gene for a useful protein is inserted into the cells of an animal, such as a sheep or goat, making them transgenic.
A transgenic cell is used to produce a cloned embryo, using the nuclear transfer method.
The embryo is implanted into a surrogate mother and develops into a transgenic animal.
The animal makes the human protein, often in its milk, where it can be collected and purified.
More identical animals can be cloned from it to make larger amounts.

Examples of human proteins made this way include alpha-1-antitrypsin (used to treat the lung disease emphysema) and blood clotting factors (used to treat haemophilia).
These proteins are used to treat human diseases and conditions.

Exam tip:

Two ideas to link: transgenic gives the animal the human gene, and cloning gives you many identical animals that all make the protein.

A human gene for a useful protein is inserted into an animal cell to make a transgenic cell; its diploid nucleus is put into an enucleated egg cell, which divides to form an embryo; the embryo develops in a surrogate mother into a transgenic sheep that makes the human protein in its milk, which is collected and purified, and more identical transgenic animals are cloned from it. — A cloned transgenic animal makes a human protein in its milk, and cloning gives many such animals.

Quick check

What is micropropagation?
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Growing new plants from explants in vitro, on sterile nutrient medium.
What are the small pieces of plant tissue used in micropropagation called?
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Explants.
What type of nucleus is put into the enucleated egg cell to clone a mammal?
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A diploid nucleus from a mature body cell.
Name a human protein made by cloned transgenic animals.
Show answer
Alpha-1-antitrypsin (or a blood clotting factor).

Written and checked against the Edexcel IGCSE Biology (4BI1) specification · Updated October 2026

Frequently asked questions

What is micropropagation and why is it used?

Micropropagation is growing new plants from small pieces of tissue called explants on sterile nutrient agar containing plant growth hormones. It is used because commercial quantities of genetically identical plants are produced quickly from a small amount of tissue, so plants with desirable characteristics are copied exactly, all year round and in a small space.

How was Dolly the sheep cloned?

Dolly was cloned by taking a diploid nucleus from a mature udder cell of an adult sheep and putting it into an enucleated egg cell. An electric shock fused them and started the egg dividing by mitosis. The embryo was implanted into a surrogate mother, and Dolly was genetically identical to the nucleus donor.

How are cloned transgenic animals used to produce human proteins?

A human gene for a useful protein is inserted into an animal cell, such as from a sheep or goat, and the cell is cloned by nuclear transfer. The transgenic animal makes the human protein in its milk, where it is collected and purified. Cloning gives many identical animals that all make the protein.

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