Starch and Amylase required practical

Morning all!
Sorry if this has already been posted, I couldn't find an answer to this actual question.

For the AQA GCSE Enzymes Required Practical what strength starch and amylase should we use.

Also, does anyone know if there is a technician's version of the lab book? We downloaded the technician's notes from the AQA website but they didn't seem to match up with the practicals!

Thanks
 
Morning all!
Sorry if this has already been posted, I couldn't find an answer to this actual question.

For the AQA GCSE Enzymes Required Practical what strength starch and amylase should we use.

Also, does anyone know if there is a technician's version of the lab book? We downloaded the technician's notes from the AQA website but they didn't seem to match up with the practicals!

Thanks
The notes from the website will match the list of practicals from the handbook - also available on the website. If you're using a lab book version they won't match up. Hope that makes sense! :) I print the handbook from the website and work from that. There is a set of teacher/technician notes and a set of student sheets.
 
It does kinda matter which amylase you use and how old it is too. We use bacterial amylase at a 0.5% solution to a 1% starch and it works ok. Not too fast, not too slow. Make it up as fresh if you can. Amylase doesn't store well. I usually do a trial run on this one and jiggle the concentrations to suit.
 
It does kinda matter which amylase you use and how old it is too. We use bacterial amylase at a 0.5% solution to a 1% starch and it works ok. Not too fast, not too slow. Make it up as fresh if you can. Amylase doesn't store well. I usually do a trial run on this one and jiggle the concentrations to suit.
Same here - worth doing a practice in case you need to tweak the concentrations a little.
 
Thanks all. Yes, amylase is fresh and made into solution an hour or so before the lesson. Our really experienced technician has recently retired and I know she used to play around with the concentrations, but we don't have the luxury of time as her hours have not been replaced. Thank goodness for this forum, we are finding it invaluable. I'll try again with 1% of each.
Thanks again
Liz
 

Peter Sigsworth

COMMITTEE
Thanks all. Yes, amylase is fresh and made into solution an hour or so before the lesson. Our really experienced technician has recently retired and I know she used to play around with the concentrations, but we don't have the luxury of time as her hours have not been replaced. Thank goodness for this forum, we are finding it invaluable. I'll try again with 1% of each.
Thanks again
Liz
@Liz Yates Depends what sort of amylase you are using - here are just a few to think about:
salivary amylase (spit which can't be used now -COVID)
pancreatic amylase has an alkaline optimum pH and is quite strong (0.1% is best)
Diastase (used in brewing, neutral optimum pH)
pancreatin (dried powdered porcine pancreas - contains pancreatic amylase)
Bacterial amylase (acidic optimum pH)
I'm afraid you should always trial the concentrations as the stock powders degrade over time. You might get away with keeping your stock powders in the freezer to prolong their shelf life and not have to trial so often.
The concs I use are:
for effect of pH on amylase -
2ml 0.5% diastase with 1 ml pH buffer
add 2ml 2% starch
buffers pH 2, 4, 6, 8,10 room temperature

for effect of temperature
5ml 2% starch added to 5ml 0.1% pancreatin take samples every 30 seconds - 7 mins worth of readings (14) - needs two spotting tiles. Half if every 1 min (7)
 
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For the amylase and Ph practical - We always have to play around with concentrations to get the correct results. it depends on which supplier you get enzyme and starch from and which type of enzyme you use( we use diastase). We start off with what ever worked the previous year and adjust from that if need be. I don't think many people like this practical as it is just a faff to get it right or nearly right. good luck
 
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