Enzymes, Cellular Aerobic and Anaerobic Respiration and Metabolism

Hello everyone, I have my GCSE Biology papers in May and June 2016 so this is my daily revision from my DG Mackean book. If you find anything incorrect just message me and I'll change it. Thank you very much everyone! 

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Science Revision
D.G. Mackean Pages 16-20
Christopher Caden…read more

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Enzymes and other factors…read more

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Enzymes and Heat
Enzymes are proteins and can not be exposed to temperatures
above 50 degrees or else they'll become denatured however heat
can be very beneficial for enzymes and a cell. Chemical reactions
happen quicker the hotter the temperature is. It has been noted
that a rise of 10 degrees Celsius will double the rate of a chemical
reaction. This holds true for enzymes. Above 50 degrees Celsius an
enzyme is subject to deformation and this means that they don't
speed up chemical reactions. This may be a factor in a cell's death
if exposed to too much heat. Scientists can take advantage of this in
experiments. It is called control and it tests if a protein is an
enzyme. If this substance still carries out chemical reactions after
being heated to 50 degrees it can't be an enzyme.…read more

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Enzymes and pH.
There is not one type of enzyme and all the different types of
enzymes work well at different levels of pH. For example an enzyme
in your stomach works best at a pH of 2, but amylase in your saliva
would fail to function at this pH level. In cells most enzymes work
best at 7 or neutral. This is called the optimal pH level but optimal
can also apply to other aspects, for example you also have optimal
temperature. Unlike heat if an enzyme is exposed to a pH level it
doesn't like its not permanently damaged unless its at the extreme
ends of the scale.…read more

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Enzymes are specific.
This means that enzymes are suited to only work with one substance
and will usually only work with that one substance. This ensures
that an enzyme which breaks down substances doesn't start to
break down needed and intact substances. You can almost think of
the enzyme as a "lock" and it will only work with it's specific "key"
which is the substance. This means that if a reaction happens in
stages with the substance changing various times a new enzyme is
needed. Most enzymes end in "...ase" and they tend to be named on
what they work with. For example the enzyme that works with
proteins is named protease.…read more

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Amount of Enzymes
Not only the temperature and pH affect how well and how fast
reactions occur, the number of enzymes themselves affect how fast
a reaction occurs. With more enzymes you have faster reactions.
This is why the nucleus is the brain of the cell, it dictates how many
enzymes are made.…read more

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