You are here:  Home > Genetic Technology > GM Proteins > Chymosin
University of Bristol
Wellcome Trust
Recommended by:
Society of Biology
PEEP for Physics & Ethics at GCSE


A board laden with hard cheeses and biscuits.Micro-organisms that have been genetically modified have been used in the manufacture of many therapeutic proteins and vaccines. There are now growing biopharmaceutical and 'pharming' industries. The technique has also been applied successfully in the food industry, for example the use of the GM protein chymosin in making hard cheese.

In 1988, chymosin was the first enzyme from a genetically-modified source to gain approval for use in food.

The DNA encoding the protein chymosin must first be isolated from calf cells. Then as described in GM proteins a copy of this DNA is inserted using plasmids into yeast cells through bacterial transformation. The modified plasmids are then copied by the yeast cells as they reproduce and chymosin identical to the animal protein is made by the yeast. 

Today about 90% of
the hard cheese in the
UK is made using
chymosin from
genetically-modified microbes.

Question: GM chymosin is used to make “vegetarian cheese”. As it is an animal protein, is this strictly accurate?

Traditionally, chymosin was extracted from calves’ stomachs for cheese making. Is GM chymosin a more ethical form of the enzyme to use in cheese making?

Explain your reasoning for both questions.


 Alpha-1 Antitrypsin

What's your opinion?

Average rating

Not yet rated

Read comments

speech bubble  No comments yet. Why not be the first person to add one?

Bookmark this pagefacebook myspace bebo delicious diigo stumbleupon twitter reddit yahoo google


Further reading:

See the information on Chymosin from the National Centre for Biotechnology Education at Reading University