Enzymes Flashcards
(39 cards)
Enzyme
Is a protein that speeds up the rate of a chemical reaction without being used up ( biological catalyst )
How do enzymes function
The active site which has a complementary shape for the raw material( substrate ) to fit into.
In the active site the raw material is broken down (or joined together in some reactions ) to make a product .
Conditions required
Optimum at 37oC
And usually optimum at pH 7 ( except stomach protease - pH 3 )
When active site is denatured this because ….
Active site shape is altered
Substrate will not fit (no longer complementary )
Lock and key model
Enzyme specificity ( enzymes active site will only fit one type of substrate ) , just like one type of key will only fit into a lock
Each enzyme only works with one other substrate ( enzyme specificity ) when they collide EG protease with protien
Starch is Brocken down into its product of glucose by amylase enzyme . Protiens cannot be broken down by amylase because ………..
Amylases active site is not complementary in shape to protein so will not be able to break it down
Is denaturation irreversible
Desaturation means ( rate of reaction)
Yes
Decreases dramatically , other factors can also reduce the rate of reaction
Inhibitors
Enzyme inhibitors are molecules that fit loosely or partially into the active site but are not broken down
How would this affect the enzymes rate of reaction , why (inhibitors)
Rate of reaction decreeases as the inhibitors block the substrate from binding to the active site
The effect of temperature on enzyme activity iodine - indicator
Starch - substrate
glucose - product
Colour change
Starch ——————————— glucose
Amylase
Blue - black to yellow - brown
The effect of temperature on enzyme activity method
Put 5ml of amylase into a boiling tube and place in a water bath at 0oC for 5min
Put 2 drops of iodine into each section of a spotting tile
Put 10ml of starch into a small beaker
Add the starch to the amylase then immediately take a drop from the solution and add to a spotting tile
Test every 30sec until the iodine no longer turns blue/black or until 8min is up . Record the time taken for iodine to no longer turns blue/black
Repeat this experiment at 25 , 40 , 60 , 80 degrees
Results title
A graph showing…
A table showing …..
Time taken for starch to be broken down by amylase at different temperatures
Conclusion describe and 0oC
40oC was the optimum temperature for amylase as it broke down starch down fastest at this temperature , 0oC took a long time as did 60oC whereas at 100oC the enzyme didn’t work (denatured )
At low temperatures , less kinetic energy , less collisions between substrate and enzymes therefore less enzyme substrate complex’s are formed therefor slower rate of reaction
60oC and 100oC
As the temperature increases to 40 more kinetic energy , more collisions between enzyme and substrate therefore more enzyme substrate complex’s are formed . This is the optimum rate of reaction .
At temperature above the optimum temperature , enzyme becomes denatured therefore the reaction stops
The effect of pH on enzyme activity
Put 2 drops of iodine into each section of the spotting tile
Put 5ml of torch into a small beaker and add 2ml of buffer of pH 4 , pH 7 , pH 10 (Iv)
Add 5ml of amylase
Immediately take a drop from the solution and add to the spotting tile
Test every 30sec until the iodine no longer turns blue-black or until 8 min is up record the time taken for iodine to no longer turn blue-black (dv)
Repeat this experiment using the other pH buffers
Titles
A table showing…
A graph showing…
How different pH s take longer/slower to digest starch using amylase
Controlled v , fair and accurate , reliable
Amount of amylase and starch and drops of iodine
Keep everything the same except pH , measure accurately
Repeat and average
Optimum
Th max rate of enzyme activity
Describing graphs , temperature
Low temperature means enzyme and substrate molecules have less kinetic energy and move slowly therefore there are less collisions and a low rate of reaction .
As temperature increases , kinetic energy , collisions and rate of reaction increases the optimum temperature is the maximum rate of reaction
Increasing the temperature above the optimum denatures, the enzyme , enzyme activity stops
PH (graph)
Each enzyme has an optimum pH , at either side of the optimum pH , they work less well because the incorrect pH changes the shape of the active site (denatured) irreversibly.
Therefore less product is made so Rae of reaction falls
Enzyme concentration graph
(X ) is a growing graph /
(Y) is a straight line —-
As enzyme concentration increases , the rate of reaction increases (x) , this is because there are more active sites for substrate to attach to . If the enzyme concentration continues to increase , the rate of reaction levels off (y) because there is not enough substrate molecules to react with the extra enzymes
Biological washing powder
Contains enzymes for breaking down difficult to remove stains , these enzymes are thermostable ( work at a wide range of temperatures ) they break don large insoluble stains into small , soluble molecules that dissolve in water
Digestion
The break down of large complex insoluble molecules into small soluble ones
Why are enzymes necessary for digestion
To break down food molecules so that they are soluble and small enough to be absorbed onto the bloodstream where they can be used by the body
