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10 things you need to know about:

ENZYMES

     

     

bulletThey are molecules made of PROTEIN and are found in every living cell, from simple bacteria and yeast, to the most complex animal or plant.
bulletBecause they are proteins they are very sensitive to changes in temperature or pH (see point 6), and also to the presence of INHIBITORS like heavy-metals.
bulletEnzymes are biological CATALYSTS - i.e. they are needed in small amounts to speed up the rate of reaction without being changed themselves.
bulletEnzymes have a special area on them called the ACTIVE SITE – this is where the chemical reaction with the SUBSTRATE takes place
bulletThe ‘LOCK AND KEY’ model explains this:

 

O2

 

 

 

 

 

 

 

 

 

    CATALASE enzyme

2H2O2                                                 2H20 + O2

Hydrogen Peroxide                                                                             Water Oxygen

bulletQ10 = 2 "For every 10°C rise in temperature, the rate of reaction approximately doubles". This is because the enzymes receive more KINETIC ENERGY, therefore there is more chance of collision with a substrate molecule.
bulletThe OPTIMUM temperature is the temperature at which reactions proceed the fastest ( the same applies to ‘optimum pH’)
bulletAfter the optimum has been reached enzyme structure is rapidly destroyed – this is called DENATURING. (not ‘killed’, ‘dead’, etc)
bulletEnzyme names end with –ASE e.g.. Catalase, Amylase, Lipase, Maltase. The exception is PEPSIN (actually a protease enzyme) that coverts proteins to polypeptides in the stomach.
bulletQuestions about enzymes in the exam will be found in the DIGESTION topic and the RESPIRATION topic mainly.

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