The aim of the investigation is find out the optimum temperature at which rennin will clot milk.

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        Biology Coursework

Aim: The aim of the investigation is find out the optimum temperature at which rennin will clot milk.

Prediction: I predict that at the mentioned temperatures renin will take that many amounts of minutes to clot milk. As the temperature increases the rate of reaction will increase. When it reaches a particular temperature the rate of reaction falls, this is due to the denaturing of the enzyme.

Scientific Knowledge and theory

Enzyme: An enzyme is a catalyst, which is used to speed up a reaction without itself changing chemically or physically.

Lock and key theory: Emil Fischer suggested the lock and key theory in 1894. The lock and key theory is simply a way of describing how specific an enzyme is for its substrate.  Just like a lock requires a specifically shaped key for it to work so does an enzyme.  Each enzyme is a protein that is a polypeptide chain folded into a complex 3 dimensional structure.  Part of that structure contains the active site, which is where the enzyme can bind to the substrate on which it will perform some chemical reaction.  Because each enzyme performs a specific task on a specific substrate the active centre of the enzyme can be considered to be the "lock" which requires the specific "key" or substrate to perform the function.  

Collision Theory: Theory of reaction rates states that effective collisions between reactant molecules must occur in order for the reaction to occur. The theory is that the number of new compounds formed during a chemical reaction equals the number of molecules colliding, times a factor that corrects for low-energy collisions. It is possible to change the speed of reactions by altering the conditions that the substance/s are in. These being –

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  • Changing the surface area - Making the surface area greater increases the chance of particles colliding.
  • Catalysts - This is a substance, which alters the rate of reaction without being used up its self.
  • Enzymes - An Enzyme is an example of a catalyst. Only each enzyme has a special shape, this causes each enzyme to be specific to a reaction.
  • Changing the concentration - The higher the concentration the more particles there are within the same amount of space. This increases the chance of collisions.
  • Changing the temperature - ...

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