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    I have to do a mock practical exam by3
    it is to find the effects of substrate concentration on catalysed enzyme activity

    it is using 5% powered milk which has casein
    and 0.5% trypsin

    please could someone give me a method? I am so confused
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    Trypsin will break down casein, so you should expect the "milk" to become watery/clear if broken down fully. Your substrate is the milk powder, so you want to vary the amount used, and keep the enzyme amount the same.

    Make up an enzyme solution if not already made, and then make up increasing concentrations of milk solution e.g. 5g, 10g, etc. in the same volume e.g. 200 ml.

    Then add the enzyme to all of them. It should easily break down the small amount of milk, so it will go clear. At some point, the amount of substrate, milk, will be more than what the enzyme can break down, so the cloudiness will persist.

    You can then plot the concentration of milk where the enzymatic activity reached plateau. The graph should look like a line going up then levelling off (not at all cloudy, slightly cloudy, quite cloudy, really cloudy, etc.).

    Here are some general practical tips:

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    (Original post by Flying Cookie)
    Trypsin will break down casein, so you should expect the "milk" to become watery/clear if broken down fully. Your substrate is the milk powder, so you want to vary the amount used, and keep the enzyme amount the same.

    Make up an enzyme solution if not already made, and then make up increasing concentrations of milk solution e.g. 5g, 10g, etc. in the same volume e.g. 200 ml.

    Then add the enzyme to all of them. It should easily break down the small amount of milk, so it will go clear. At some point, the amount of substrate, milk, will be more than what the enzyme can break down, so the cloudiness will persist.

    You can then plot the concentration of milk where the enzymatic activity reached plateau. The graph should look like a line going up then levelling off (not at all cloudy, slightly cloudy, quite cloudy, really cloudy, etc.).
    Here is an AQA resource which complements Flying Cookie's response, I strongly recommend you review this resource.

    Resource: http://filestore.aqa.org.uk/subjects...X-TN-JUN12.PDF

    Hope it helps.
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    (Original post by Flying Cookie)
    Trypsin will break down casein, so you should expect the "milk" to become watery/clear if broken down fully. Your substrate is the milk powder, so you want to vary the amount used, and keep the enzyme amount the same.

    Make up an enzyme solution if not already made, and then make up increasing concentrations of milk solution e.g. 5g, 10g, etc. in the same volume e.g. 200 ml.

    Then add the enzyme to all of them. It should easily break down the small amount of milk, so it will go clear. At some point, the amount of substrate, milk, will be more than what the enzyme can break down, so the cloudiness will persist.

    You can then plot the concentration of milk where the enzymatic activity reached plateau. The graph should look like a line going up then levelling off (not at all cloudy, slightly cloudy, quite cloudy, really cloudy, etc.).

    Here are some general practical tips:

    thank you for the help!
 
 
 
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