GCSE Biology Edexcel B3 Topic 3

I made these revision notes myself. I got an A* in Biology GCSE and 80 UMS (full marks) in the B3 exam using only these notes.

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B3 Topic 3 `Biotechnology'
Biotechnology: using living organisms (especially microorganisms) to produce useful products (e.g. food,
medicines) or to provide people with services (e.g. waste management, water purification).
Biomolecule: a chemical or substance produced by a living organism.
Microorganisms: living organisms that can only be seen under a microscope.
Changes in foods such as milk and meat are due to microorganisms ­ bacteria and fungi. These
microorganisms produce enzymes that change molecules in the original substance into different molecules.
For example, bacteria act on a protein called casein in milk when it turns to cheese.
Now, processes like this are called biotechnology. Biotechnology can be used for many different things, such
as medicine.
Fermenters
Modern biotechnology often involves big steel vessels, called fermenters, in which microorganisms are
grown. Inside these fermenters, the microorganisms are provided with exactly the right conditions to
encourage them to grown and produce the substances we desire.
For example, the fungus Pencillium is used to produce the antibiotic penicillin.
Before the microorganism is put into the fermenter, it is essential to kill all other microorganisms already in
there as they might grow instead (sterilisation).
Not doing this would cause a problem as these unwanted microorganisms will use up the nutrients given into
the fermenter and not allow the desired microorganism to grow to the largest yield.
The fermenter is sterilised using high-pressure steam. Everything that is added to the fermenter is first
sterilised before entering to prevent microorganisms getting into the culture (contamination).
These are called aseptic precautions.
Optimal conditions for the microorganism are supplied, so that it produces as much product as possible in the
shortest time. These conditions include:
o NUTRIENTS: sources of carbohydrates (energy) and nitrogen (nitrates, to make proteins) are added
such as sugar and ammonium ions. This is added to the food culture medium.
o AN OPTIMUM TEMPERATURE: this is so the enzymes in the microorganism can work at a fast rate but
don't get denatured. As the microorganisms produce heat by respiration, the fermenters must be
cooled using a water jacket.
o OPTIMUM PH: the enzymes work best at this pH.
o OXYGEN: this is provided by bubbling sterile air into the fermenter, so the microorganism can respire
aerobically.
o AGITATION: produced by a stirrer, to mix the oxygen and nutrients into all of the liquid.

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Factors affecting growth in yeast
Yeasts are widely used in biotechnology for making bread and alcoholic drinks such as beer and wine. Yeast
can also be grown on an industrial scale in fermenters to produce enzymes and medicines such as penicillin.
The pH of the culture is one of the factors controlled in the fermenter to create optimum conditions. If the pH
is too acidic or too alkaline, the yeast enzymes do not function properly.…read more

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These factors can affect both the speed at which yogurt is made from milk, and also the type of yoghurt is
produced.
Enzyme Technology
Meat contains fibres which are tough if you don't beat it to break up the fibres. Pineapple juice, which
contains enzymes that tenderise the meat, is sometimes added to meat in recipes to break down the protein
fibres.
Yoghurt production
The equipment is sterilised before production to kill any unwanted microorganisms.…read more

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Special stain removers can be bought to remove wine, blood or oil stains. Some are solvents but some
contain specific enzymes that will break down the stain.
Enzymes for cheese-making
Chymosin is the enzyme used to make the curds and whey, the beginning of the cheese. Traditionally, the
enzyme is from calves' stomachs. Chymosin affects the protein in the milk, making it separate into curds,
protein and fat, and whey.…read more

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Cellulase is produced by the microorganisms which are found in the digestive system of cows. This enzyme
helps them break down the cell walls in grass.
Breeding plants
Unfortunately, as the human population grows many people all over the world do not have enough food.
The World Health Organisation has said there is a `global food security crisis'.
Global food security: the ability to produce enough food in the future to feed everyone in the world.…read more

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It can be used as a fuel for cars and buses.
Biodiesel
This can be used in vehicles and is very similar to normal diesel. The vehicle doesn't need to be altered much
for it to run on biodiesel.
Biodiesel is made from vegetable oils, animal fats or waste cooking oil.
Ethanol
Ethanol can be burnt as fuel. It's a cleaner fuel than petrol or diesel, producing fewer pollutants.
Ethanol is produced by using yeast to ferment glucose.…read more

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Agrobacterium tumefaciens contain plasmids. These are removed from the bacteria, `cut open' and inserted
into the herbicide-resistance gene.
4. The genetically modified bacteria then infect the target plant. A crown gall on the plant will occur which is
swelling of the plant.
5. This is when the bacteria have inserted their genes into the plant's DNA.
6. Tissue from this crown gall is grown in a medium. The cells contain the herbicide. Those that grown must
contain the herbicide-resistant gene.…read more

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7h0m45

Thank you sooo much these notes have really helped me with my GCSE's!

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