OCR exam board Trypsin enzyme RP - any tips?

I have heard this practical is notorious for not working, and I don't have enough time to trial it myself.

Any tips on getting some good results on this one?

Thank you x
 
Just check the enzyme clears the milk solution.

The milk powder takes a while to dissolve.

The only issues I've had is the AQA one using a colorimeter where they are supposed to take a reading after 4 minutes, which the kids can't do, so we got rid of the colorimeters and do it the old fashioned seeing an X way.
 
I'm not familiar with the OCR version of this practical, but if it uses powdered milk, make sure the milk powder is in date. Milk powder is one of the few things that won't work if its out of date.
 
I'm not familiar with the OCR version of this practical, but if it uses powdered milk, make sure the milk powder is in date. Milk powder is one of the few things that won't work if its out of date.
Or even if it is in date, but been open a while. I find I have to buy fresh every year.
 
I'm not familiar with the OCR version of this practical, but if it uses powdered milk, make sure the milk powder is in date. Milk powder is one of the few things that won't work if its out of date.

it's seeing text on the observation sheet through the tube, and doing a Serial Dilution of the enzyme, I don't see why it is notorious for not working.
 
This practical works every time.. powdered milk (yes it's got to be in date )
It needs trialling or how will you know if the enzyme is still active ..
 
This practical works every time.. powdered milk (yes it's got to be in date )
It needs trialling or how will you know if the enzyme is still active ..
I did trial it, but I think the enzyme isn't active unfortunately.

Is there any concentration of the milk powder?

I will see what other enzymes I have lurking somewhere...
 
I did trial it, but I think the enzyme isn't active unfortunately.

Is there any concentration of the milk powder?

I will see what other enzymes I have lurking somewhere...
for aqa where we investigate temperature it's

0.5% trypsin solution •
3% solution of milk powder •
pH 7 buffer solution

You could try another protease.
 
We do OCR and have actually found this to be one of the more reliable enzyme practicals!
We use Marvel Milk 4% and Trypsin 2%. As has already been mentioned, both need to be fresh.
I always do a trial to get some sample timings so the teacher knows roughly what to expect in the lesson.
 
Just ran this practical yesterday using Sainsburys skimmed milk powder 3% strength well mixed in water , and 0.5% trypsin dilution well mixed , pH7 buffer , and it worked fine. The reaction happened within 5 minutes . Trial it before use jus to make sure. If the milk powder is aged and lumpy buy some fresh.
 
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