Biology GCSE Revision
Topic 1: Biotechnology
• The food industry has traditionally made much use of biotechnology in the production of many food items, for example cheese, yoghurt, alcohol, chocolate, soy sauce and, more recently, mycoproteins and prebiotics.
• Plants can be modified to be resistant to herbicides and/or pests and this has environmental implications.
• The pharmaceutical industry generates a lot of money annually and consideration of the contributors to this profit and its distribution is needed.
• Stem cell research must consider many ethical questions, including the definition of ‘life’.
• Organisms can be genetically modified to produce substances, including medicines that are of direct use to human health.
· Citric Acid
The mould fungus Aspergillus Niger is used to produce citric acid.
Citric acid is added to fizzy drinks, sweets, jams and jellies to enhance (bring out) the flavour in them.
Citric Acid is also used to prevent the breakdown of Vitamin C in food.
v Vitamin C
Different species of the bacterium Acetobacter are used to produce Vitamin C.
To produce invertase, we use the yeast fungus called Saccharomyces cerevisiae. The enzyme (invertase) converts the sugar sucrose into glucose and fructose which are different types of sugars, which makes the taste sweeter.
As well as saving money, this also means that lower-calorie sweets foods are being produced. It is used in the manufacture of sweets.
v Glutamic Acid
The amino acid called Glutamic Acid is produced by Corynebacterium glutanicum.
When it is neutralised it makes a sodium salt called Monosodium glutamate (GTM).
When added to food, this enhances the flavour. It’s popular in Chinese food.
Cheese is made by the use of a substance called Rennet, which is vital to the process of making cheese.
Rennet is traditionally obtained from the lining of a calf’s stomach. It contains an enzyme called Chymosin which makes the milk curdle/clot.
However, this is a problem for vegetarians as they wouldn’t want to eat cheese which uses rennet from animals, so vegetarian cheese can be made using Genetically Modified (GM) Bacteria. This is much better because it is more acceptable to vegetarians, it contains fewer impurities and its activity is more predictable.
§ Enzymes are used to cut the Chymosin gene from the cow.
§ A vector is used to put the gene into the bacteria DNA.
§ The DNA then starts to produce Chymosin.
v Gelling Agents
Gelling agents are added to food to make it thicker and less runny. Ice creams, jellies, etc contain gelling agents.
An example of a common gelling agent is Gelatine which comes from animal bones.
However, foods which contain Gelatine are unacceptable to vegetarians. There are alternatives to Gelatine such as Carrageen Extract which come from the reddish purple seaweed Carrageen.