Edexcel Biology B3 topic 1 - Biotechnology

Pretty much everything for the Biotech section of the Edexcel Biology course

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Biology B3 biotechnology (EDEXCEL) revision
Important processes
Production of Yoghurt
1. Milk is pasteurised to kill any pathogens and cooled to 450C
2. A culture of Lactobacillus Bulgaricus is added to the warm milk
3. The bacteria break down the lactose sugar in the milk into lactic acid
4. The lactic acid lowers the pH of the mixture
5. The milk protein, casein, coagulates causing the mixture to thicken and `set'
Production of soy sauce
1. Soya Beans are soaked and then pressure cooked
2. The Resulting mash is mixed with flour and culture of fungus Aspergillus Oryzae is added
3. The Aspergillus Oryzae secretes enzymes (amylase) which breaks the starch molecules to
smaller sugar molecules
4. The mixture is heavily salted and Lactobacillus Bulgaricus and yeast are added, this stops the
Aspergillus secreting enzymes
5. The mixture is left to ferment for several months producing a red-brown mixture
6. The mixture is filtered, pasteurised and bottled
Producing herbicide resistant crops
1. Get a plant that is already resistant to the herbicide and select the gene needed
2. Cut out the Herbicide Resistance (HR) gene from the plant cell using restriction enzymes
3. Agrobacterium Tumerfaciens bacteria contain a loop of DNA called a `plasmid'. Remove it
from the bacteria and cut it open using a restriction enzyme
4. Insert the HR gene onto the sticky ends of the bacterium plasmid using ligase enzymes
5. Allow the Agrobacterium to infect cells of the target plant
6. The bacteria cause a crown gall to grow on the plant. The genetic material of the gall cells will
contain the HR gene
7. Grow a tissue culture of the gall cells in a medium containing the herbicide; those that grow
must contain the HR gene
Production of insulin
Insulin is a protein normally produced in the pancreas that takes sugar out of the blood to make fat.
This helps keep blood sugar levels fairly constant. People with diabetes cannot produce insulin
1. Gene for human insulin is identified
2. Gene inserted into a plasmid
3. Plasmid inserted into bacterium Escherichia coli. This bacterium now starts producing insulin
4. The bacteria are grown in fermenters
5. Bacteria are killed by heat sterilisation and the insulin is extracted and purified
Other uses of microorganisms

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Microorganism Use
Acetobacter Used in the production of Vitamin C
Saccharomyces Ceravisiae ­ a type of yeast Produces the enzyme invertase which converts
sucrose into glucose and fructose to produce
the semi-liquid centre in some chocolate eggs
Aspergillus Niger To Produce Citric acid which is used as a
flavouring and preservative in fizzy drinks
Corynebacterium Glutamicum To produce glutamic acid which is turned into
MSG, a flavour enhancer
Mucor miehei This fungus produces the enzyme Chymosin
which is used as an alternative to Rennet (from…read more

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Plant Stanol Esters can lower cholesterol. High levels of cholesterol can lead to heart
problems
o Prebiotics are foods containing Oligosaccharides.…read more

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