The effect of changing enzyme concentration on rate of reaction

Note by AD_, updated more than 1 year ago
Created by AD_ over 7 years ago


AS Level AS Biology (IAL AS Biology Unit 3 ) Note on The effect of changing enzyme concentration on rate of reaction, created by AD_ on 23/04/2014.

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Independent: Conc. of enzyme

Control: Temperature Volume of enzyme Volume of substrate Concentration of substrate pH

Method: protease (1% trypsin) & casein solution Make up diff. conc. enzyme using distilled water. Set up water bath for temp. keep constant. Place 1 test tube of 5cm3 casein solution into water bath alongside second tube contain 2cm3 of 0.2% trypsin. Allow acclimatise 3mins so that at same temp. then add trypsin to casein, start stop clock. Time how long it takes for casein solution to turn transparent. (Mark ‘X’ on the other side of tube, as soon as seen through solution stop clock). Repeat a further 2 times then repeat for next concentration.

Method:  catalase in yeast & hydrogen peroxide Use 1st conc. yeast solution, acclimitise to desired temp. alongside separate tube of hydrogen peroxide. Set up gas syringe and set to 0. Quickly add peroxide to yeast & attach gas syringe. Read off volume of gas produced every 10mins until 3 readings are the same. Repeat 3 times for each conc. yeast solution.

Calculations & outcome:Rate = 1/time Conc. increases, rate of reaction increases until plateau point where all enzymes metabolised all substrate immediately.

Calculations & outcome:Rate = initial rate of reaction = gradient at steepest point from graphs of vol. against time for each conc. Outcome as protease.

Evaluation issues: Accurately make up diff. conc. Maintain constant temp. Difficult see cross through solution Identify end point consistently


Evaluation issues: Attache syringe slow allow loss gas. Reaction going too quickly to read. Inaccurate reading gas syringe. Inaccurate reading syringes in making up dilutions.


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