rqp enzyme substrate

Question 1

what’s an enzyme substrate complex?

Answer 1

a temporary molecule formed when the substrate binds to the enzyme

Question 2

higher enzyme conc.=

Answer 2

the greater the number of active sites available and the greater the likelihood of enzyme-substrate complex formation

Question 3

independent variable

Answer 3

protease conc.

Question 4

dependent variable

Answer 4

time taken for enzyme to break down substrate (seconds)

Question 5

control variables

Answer 5

temp-measure water bath with thermometer, constant for repeats
vol of enzyme solution- 2cm3 each time
vol of substrate- 5cm3 of caesin solution each time
conc of substrate- same conc of caesin for all repeats

Question 6

control experiment

Answer 6

enzyme conc of 0- DISTILLED water, can be added to caesin solution

Question 7

method

Answer 7

-Set up a water bath so that the temperature can be kept constant.
-Mark an ‘X’ on one side of a test tube using a marker pen.
-Fill this test tube with 5 cm³ of casein solution and place it into the water bath alongside a second tube containing 2 cm³ of the lowest concentration trypsin (e.g. 0.2%).
-Allow both substances to acclimatise for 3 minutes so that at they are both at the same temperature.
-Add the test tube of trypsin to the casein and start the stopwatch.
-Time how long it takes for the casein solution to turn transparent. This is when you can clearly see the shape of the ‘X’ mark.
-Repeat this a further 2 times and then repeat for the other concentrations of trypsin (e.g. 0.4%, 0.6%, 0.8% and 1%).

Question 8

initial rate of reaction calculation

Answer 8

Rate= 1- Time (seconds)

Question 9

induced fit theory

Answer 9

the binding of a substrate to an enzyme causes a change in the shape of the enzyme so as to enhance or inhibit its activity.

Question 10

how is the substrate limiting

Answer 10

If the amount of substrate is limited, at a certain point any further increase in enzyme concentration will not increase the reaction rate as the amount of substrate becomes a limiting factor

Question 11

how does substrate conc. affect rate of reaction

Answer 11

-The higher the substrate concentration the faster the rate of reaction
-More substrate molecules means more collision between enzyme and substrate so the more likely an active site will be used by a substrate
-at which point a saturation point is said to have been reached
-Substrate concentration will decrease over time.
The rate of reaction will therefore decrease over time.
-This means the initial rate of reaction will be fastest throughout the reaction