Practical 9- Investigation into the effect of enzyme or substrate concentration on enzyme activity Flashcards
Where is the enzyme catalase found?
In all living tissue - is produced by any eukaryotic cell
Which type of enzyme is found in all living tissue and is produced by any eukaryotic cell?
Catalase
What does the enzyme catalase do?
Increases the break down of hydrogen peroxide, a toxin produced as a by-product of metabolic reactions in cells
Which enzyme breaks down hydrogen peroxide?
Catalase
Hydrogen peroxide
A toxin produced as a by-product of metabolic reactions in cells
What is hydrogen peroxide in this practical?
The substrate
What’s the substrate in this practical?
Hydrogen peroxide
Describe hydrogen peroxide
Very reactive
What’s the risk caused by hydrogen peroxide and why?
Can cause skin irritation as its an oxidising agent
Equation for the reaction of catalase
2H202 ——> 2H20 + 02
What causes the paper discs to rise to the surface in this practical?
The enzyme catalysed reaction of catalase produced 02, which will form bubbles on the surface of the discs so that they rise to the surface
What do the paper discs do in this practical and why?
Rise to the surface of the hydrogen peroxide as the reaction of catalyse produced 02 which forms bubbles on the surface of the discs so that they rise to the surface
What is catalase found in high concentrations in?
Raw potatoes
Which enzyme is found in high concentrations in raw potatoes?
Catalase
What’s the first step of this practical?
Grind a 2cm piece of potato cylinder with 5cm^3 distilled water with a pestle and mortar to make a smooth paste containing the enzyme - the enzyme suspension
How big is the potato cylinder used and how much distilled water is it grinded with?
2cm, 5cm^3
What’s the name for the paste containing the enzyme created?
The enzyme suspension
Enzyme suspension
Smooth paste containing the enzyme catalase and distilled water
What do we do after grinding up the potato cylinder to create an enzyme suspension?
Place 10cm^3 of H202 in a specimen tube/test tube - do this for 5 different substrate concentrations - 2vol, 4vol, 6vol, 8vol and 10vol.
What do we place in the test tubes and how much?
5 different concentrations of H202
10cm^3
What are the 5 different substrate concentrations used?
2vol, 4vol, 6vol, 8vol, 10vol
What do we do after filling the test tubes with hydrogen peroxide of different concentrations?
Using forceps, dip a filter paper disc into the enzyme suspension and tap off the excess
What’s dipped into the enzyme suspension?
A filter paper disc
What happens father dipping the filter paper disc into the enzyme suspension?
Drop the filter paper disc into the hydrogen peroxide solution and measure the time, to the nearest second, that it takes from striking the surface to sink to float up again to the surface
What are we measuring the time of?
The time taken for the filter paper disc to strike the surface, to sink and to float up again to the surface of the enzyme suspension
What do we do after timing the paper disc in the hydrogen peroxide solution?
Remove the disc from the tube using forceps and discard
How many times do we repeat the practical at each concentration of H202?
3x
What do we repeat 3 times in this practical?
The process of putting the paper discs in the H202 at each concentration
What were the results of this practical?
The higher the substrate concentration, the faster the rate of enzyme activity
What made this practical less reliable and accurate?
-Enzyme concentration wasn’t consistent, as potato sample wasn’t completely smooth, so sometimes you’d get entire chunks of potato (and therefore more enzyme) and sometimes none
-There was no timing for dipping the discs into the enzyme suspension
-Timing depended a lot on human reaction time
What was wrong with the process of dipping the paper discs into the enzyme suspension?
There was no timing - some discs may have been dipped in for longer or shorter than others
What wasn’t consistent in this practical? Why?
Enzyme concentration as the potato sample wasn’t completely smooth, so sometimes you’d get entire chunks of potato (and therefore more enzyme) and sometimes none
