The aim of this investigation is to investigate the enzyme activity by using Catalase and Hydrogen Peroxide. I will add Hydrogen Peroxide with Catalase and use a variable which will have an affect on the enzyme activity, so that it can be investigated.

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Biology Coursework

Catalase

Aim

The aim of this investigation is to investigate the enzyme activity by using Catalase and Hydrogen Peroxide.  I will add Hydrogen Peroxide with Catalase and use a variable which will have an affect on the enzyme activity, so that it can be investigated.

Variables

The factors, which will have an affect on the enzyme activity, will be:

  • Temperature
  • Concentration of enzymes
  • pH

The variable in which I will be using to investigate the enzyme activity is the temperature.  The rest of the variables will be kept constant and only the temperatures will be changed.

Background

Enzymes help to speed up the rates of a reaction but do not get used up themselves.  They are often called Biological catalyst and they speed up the reactions in living organisms.  All enzymes are made from protein and specific enzymes are used for specific reactions.  Enzymes are re-useable and can be affected by the temperature, and its pH.  

Examples of enzymes are:

Amylase: Used to break down starch into maltose

Maltase: Used to digest maltose into glucose

Carbohydrases: Used to catalyse the digestion of carbohydrates

Lipase: Used to catalyse the digestion of fat

Proteases: Used to digest protein

Pepsin: Used to digest protein into polypeptides

Trypsin: Used to break down polypeptides

Temperature and enzymes

Enzymes happen to work best at an optimum temperature.  At low temperatures, the enzymes may become inactive and slow down or not work.  But if they get heated again, then they will work again.

If the temperature gets too hot, then the enzymes will become denatured.  This is an irreversible change; therefore they will become useless, as the active site will be changed.

In mammals, the optimum temperature for the enzymes to work in is round about 37˚C.

Concentration of enzymes

The more the concentration of enzymes become, the faster the rates of reaction will be.  As the concentration is more, then there will be more enzyme particles to collide into the substrates, meaning a faster reaction will take place.  But as more and more enzymes are added, the reaction will soon become saturated therefore no matter how much more enzymes are added, it will not speed up the reaction any more.  (As no more substrates are to be broken down into products)

pH and enzymes

Enzymes work best at a pH of seven (neutral).  If the enzymes become too acidic or to alkaline, then they will denature or become inactive.  Like for an example inside our stomach.  When amylase is digesting the food in our mouths, and then we swallow it, the amylase becomes denatured by the pH scale of the stomach.  The stomach has a pH of 1.5 to 2.5 therefore the amylase gets denatured as it works best at a pH of seven.  

Catalase

Formula:

                                       Catalase

Hydrogen Peroxide                              Water + Oxygen

                                       

                                       Catalase

                      2H2O2                               2H2O  + O2

Catalase is used to speed up the decomposition of Hydrogen Peroxide into Oxygen and Water.  The active site of Catalase matches the shape of the Hydrogen Peroxide molecule; therefore Catalase can speed up the reaction.  Catalase is an enzyme found in food such as potato and liver.  It removes Hydrogen Peroxide from its cells, as Hydrogen Peroxide is a poisonous by-product of metabolism.  Again, since Catalase is an enzyme, it works best at a pH of seven.  

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Note:  All information has been found from the web site:  and from the textbooks, ‘Coordinated Science BIOLOGY’ and ‘CGP GCSE BIOLOGY’ books.

Fair Test

To make my investigation fair, I will do the following things:

  • Repeat each experiment twice, therefore I will have three results for each experiment
  • Use the same amount of Hydrogen Peroxide for each experiment
  • Use the same type of liver, and from the same ‘actual liver’ for each experiment
  • Use a sensitive scale to weigh out the liver
  • Use the same equipment, such as the same beakers, Bunsen burners, conical flasks, ...

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