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Amy6900
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#1
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#1
I am investigating the effect of temperature on fungal and bacterial amylase. Clearly i would use water baths and iodine solution to determine how much starch had been broken down. Blue black indicating that little or no starch had been broken down, and a yellow brown colour(colour of iodine in water) indicating that all starch has been broken down into its constituent molecules, maltose.
However I am unsure on how to actually measure the degree of the colour, ie exactly how much has been broken down. I know you can use a calirometer but i am not quite sure how this works.

I would be keen on hearing how other people are doing this experiment, and their ideas and problems. Any tips on calirometers or info on how they work muc appreciated. Thanks

Amy
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GH
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#2
Report 16 years ago
#2
Hmmm, better to have suspension of the solution-starch, with the amylase. Then you can quickly see teh colour change. Put it into the cuvettes, and intot he colorimeter, at a suitable wavelength.

Read off the readings, and plot a calibration curve.
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Amy6900
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#3
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#3
Thanks for the reply...
I've done searches on the net for calirometers etc but have still not been abl eto understand this wavelenth business with it. If anyone can explain that further I would also be grateful.

Amy
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GH
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Basically you choose the wavelength of the light to shine through the cuvette. Certain wavelengths gets absorbed more by certain colours, so giving you better results. Ie larger range
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Amy6900
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#5
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#5
How would i allow fo rthe fact that even with complete breakdown of starch there would be a yellow colour from the iodine?
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GH
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#6
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You use a "blank":

-Fill cuvette with water-to about 0.5cm^3
-Add 3 drops of standard iodine

Use this as the blank, and press the "zero" button on the colorimeter so that all the readings are taken form the iodine solution, ie any change in colour form teh blank will be noted.
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Amy6900
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#7
Report Thread starter 16 years ago
#7
Thanks
sorry i keep asking questions that to u must seem easy but ive never actually seen a colorimeter before in my life.
thanks anyway!
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Amy6900
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#8
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#8
so how doe sthis calibration curve thing work? what are the axis?
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GH
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#9
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(Original post by Amy6900)
so how doe sthis calibration curve thing work? what are the axis?
Temperature vs optical density.
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