proteins

Question 1

test for proteins

Answer 1

biurets reagent

blue to purple precipitate

Question 2

RP1 steps

Answer 2

add known volume of enzyme containing solution in flask
incubate at 20 degrees in water bath until solution has reached 20 degrees
add hydrogen peroxide to the flask
secure bung connected to delivery tube and gas syringe
start a timer and measure volume of oxygen produced after 30 seconds
repeat multiple times at same and increasing temperatures.

Question 3

RP1) why should smaller intervals be used?

2) how can temperature be checked?
3) how can temp be controlled and altered?
4) how can pH be checked?
5) what is a colour standard used for?

Answer 3

1) greater accuracy and allows for clearer comparisons
2) take several readings every 2-3 minutes
3) thermostatically controlled waterbath/thermometer
4) take several readings every 2-3 minutes using a pH metre.
5) to act as a reference point/benchmark for comparisons

Question 4

PR1 milk version

Answer 4

use control samples
measure with named equipment
1)measure 2 control samples, add 5cm3 milk suspension to test tube A and B
2) add HCl to B
3)take another 3 test tubes, add 5cm milk suspension to each
4)place each in waterbath for 10 minutes at 10 degrees
5) add enzyme- 5cm3 of trypsin AND START TIMER
6)record time taken to do colourless
7)repeat at same and higher temperatures
8)find mean for each temperature
9)find rate-1/time
10)rate by time graph