Factors effecting the rate of respiration in immobilised yeast

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Factors effecting the rate of respiration in immobilised yeast

 I am looking at yeast to find the optimum conditions for it to produce more carbon dioxide as a waste product from breaking down glucose during anaerobic respiration.  

This occurs when there is too little oxygen available to enable yeast to respire aerobically in order to produce ATP.  Anaerobic respiration is a type of  in which carbohydrates are partially oxidised, with the release of chemical energy, in a process, which does not involve oxygen. Since the substrate is never completely oxidised the energy yield of this type of respiration is lower than that of aerobic respiration (A single molecule of glucose can produce 38 molecules of ATP in aerobic respiration and in anaerobic respiration it only produces 2 molecules of ATP. It occurs in some yeasts and bacteria and in muscle tissue when oxygen is absent. Saccharomyces cerevisiae are facultative anaerobes, facultative anaerobes are normally aerobic but can respire anaerobically during periods of oxygen shortage. Alcoholic fermentation is a type of anaerobic respiration in which one of the end products is ethanol.

In the experiment the yeast will be respiring anaerobically and breaking down the glucose stored in it as a waste product of this process it will also form CO2 and alcohol in the form of ethanol. This respiration process is called fermentation.
I deduce from this that the more glucose that is present in the yeast the more will be broken down and therefore more CO2 and ethanol will be produced as waste products at a faster rate. This is shown in the induced fit theory the active site to many enzymes is not exactly the same shape as the substrate but it moulds itself around the substrate as the enzyme substrate complex is formed. Only when the substrate binds to the enzyme is the active site the correct shape to catalyse the reaction. As the productions of the reaction form they will fit the active side less well and fall away from it. Without the substrate the enzyme reverts to it’s relaxed state.

Prediction

The lower the concentration of the glucose solution (substrate solution) the slower rate of respiration of the yeast so therefore the least carbon dioxide will be produced and they will be the slowest beads to rise to the surface. Ethanol is a waste product, which accumulates and eventually kills the yeast unless oxygen becomes available. Alcohol is a product inhibitor; when the end product of a metabolic pathway begins to accumulate, it may act as an allosteric inhibitor this a compound that is not in the enzymes substrate, and binds with the enzyme at a site other than its active site causing a change in the structure of the enzymes.  The forming of the enzyme - substrate complexes per second would therefore be lowered, and further production of the end product decreased or prevented. If the production of ethanol is slowed, then so will be the production of carbon dioxide and then the beads will not rise.  

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The solution used with the highest glucose concentration will have the beads that rise to the top the most quickly. This is because the higher the glucose concentration the more chance there is of the substrate colliding with the enzyme and thus forming more enzyme substrate - complexes per second causing the yeast to produce more carbon dioxide and rising to the surface quicker.  

Hypothesis

The higher the glucose concentration of the substrate the faster all the immobilized yeast reaches the surface of the substrate solution.  

Plan.

The key ...

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