Enzymes are sensitive to different temperatures, pH levels etc… Certain enzymes work best in acidic conditions, whereas others work best at alkaline conditions. In relation to Trypsin, it works best at acidic conditions. The reason for this is because Trypsin is an enzyme that is found in our stomach to breakdown proteins.
Some substances can actually block the active sites of an enzyme and not allowing the substrates to fit into the active site. These substances that block the active site of an enzyme are called inhibitors.
Here is how enzymes work:
This is how the substrate fits into
the active site of enzyme.
This shows the enzyme has broken
down the substrate.
When the active site is blocked the substrate can not fit into the
enzyme because there is another
substance in the active site,
this means there is no reaction
going to take place.
Enzymes are molecules that have a special shape and structure. Each enzyme only controls one type of reaction.
For example, a protein enzyme will only react with a protein substrate.
When there is more heat given, the particles move faster and they collide with one another more. When there is less heat there would be less energy and less collisions taking place.
The diagram below shows the difference in movement of particles in cold and hot conditions.
this means there is no reaction going
-Here there is not much -Heat is added so
heat added into the particles particles move at a fast rate
-Particles are moving because there is more energy.
at a slow rate because they have
less energy. –collisions take place at a fast
rate.
-There collisions occur less frequently.
taking place so the reaction
will take a long time to
take place.
The heat affects the enzyme by speeding up the rate of reaction. If there is more heat given then this means there is more energy given. This means there will be more collisions taking place between the substrate and the enzyme.
If too much heat is given to the enzyme, the enzymes will change shape and won’t have a stable active site for substrates to fit in and no reaction will be able to take place.
The enzymes need to use activation energy. This is a minimum amount of energy required for a reaction to begin.
When the particles (enzyme and substrate) collide, if they don’t have the activation energy the reaction will not occur. But if they collide they do have activation energy the reaction will occur.
APPARATUS:
- Semi-skimmed milk
- Trypsin solution
- Hydrochloric acid
- Test tubes
- Beakers
- Thermometers
- Stop-clock
- Measuring cylinders
- Pipettes
- Water Bath
- Ice
- Test tube
DIAGRAM:
METHOD:
1: First I will make a colour standard that I will compare with all of my other test tubes at different temperatures and compare it to see if the milk has been digested. To make the colour standard I will mix 5cm3 of hydrochloric acid with 5cm3 of semi-skimmed milk. The substances should then go translucent. This will show the milk digested.
2: Then I will measure the room temperature and add 5cm3 of trypsin and 5cm3 of semi-skimmed milk together. Then I will mix it together and start the stop clock. Once the mixture has become the same colour as the colour standard I will stop the stop clock and record the time taken for the milk to be digested on to a table.
3: Then I will repeat the experiment a few more times but changing the temperature and mixing the too solutions once they are both at same temperature. Then I will again compare it to my colour standard and record the time taken for the solution to be digested.
I will record my results onto a table at first and then plot my results onto a graph to see if there is a pattern or not.
I will be changing the temperature and I will be recording the time and stopping it once it has digested. I will need to be accurate for when I’m reading the temperatures off the thermometer.
I will use water baths and ice to change the temperatures.
I will need to make sure that I will mix the trypsin and semi-skimmed milk together at the same time.
RESULTS:
CONCLUSION: As you can see from my results that as I increased the temperature the reaction had taken place quicker. This shows that the enzyme trypsin worked better at a high temperature because a reaction took place and the milk (substrate) could fit into the trypsin’s active site so that the reaction can take place and the milk could get digested.
If you look at my graph you can see that when the temperature was at 5°C there was no activation energy so the milk couldn’t get digested and milk couldn’t fit into the active site of the trypsin. This means that the particles were moving very slowly and the there was not much heat and energy given to the particles to collide that’s why it denatured and no result was found while doing the experiment.
The same thing happened to the enzymes at 80°C. This time there was too much heat and activation energy given to the enzyme and milk and there were too many collisions taking place so the enzyme denatured so milk could not fit into the active site. This is also why no reaction took place and no result was found.
If you refer back to my conclusion you can see that I predicted that the higher the temperature would be, the faster the reaction will take place. I also gave rough predictions at what temperatures the enzymes will work best at and what temperatures the enzymes would denature at. My predictions was correct because at 24°C the time of reaction was very high and over 7 minutes, as for 55°C the time was very low and under 3 minutes. This shows that the milk digested at faster at 55°C.
In my graph you can see a smooth curve line of best fit. This line shows a pattern that my results had given. All the points went at the same direction apart from the point at 39°C. This point was the only anonymous point in my graph. This pattern shows the temperatures the enzymes work best at and it shows me where I might have gone wrong, for example the anonymous point.
I also predicted a rough graph of what I think my results would look like and it looks very similar to my final graph.
From my results I have learnt that enzymes work best at high temperatures and if there is too much heat given to the enzymes then there would be too much energy given, which would mean there would be many collisions and the enzymes will denature. Also I found out if there is too little energy given then there would be fewer collisions taking place and less heat and energy will be given this would denature the enzyme also.
EVALUATION: The experiment worked out quite well as I got good results to do a good graph in. I found one anonymous point that occurred at 39°C. This could of occurred because I might have not measured the trypsin solution properly or I might have not measured the milk properly. I could have not heated up the solution at the same temperatures and allowed it to be at different temperatures and then mixed the two solutions together.
There are many possibilities of why an anonymous point occurred. It could have been for various reasons such as whilst I was heating up the solutions in the water bath the window might have been opened and the wind could have altered the temperatures to be different. I might have not stopped the stop clocks at the time of the reaction had taken placed and might have overrun the time.
The results were quite accurate as I got a smooth line of best fit and I found a pattern that matched my prediction too.
If I were to do this experiment again I would write down the different temperatures that I want the solutions to be at and not have to wait until they are the same temperature because I would save more time like this. Also I would make sure I have a reliable stop clock that will stop when you press the stop button and also I would do the experiment again for about 4 times for accurate results from the stop clock and that the milk has been digested fully and has turned translucent. Finally because I was doing the experiment in a group and we were all over the place we didn’t know what results to put down because they were doing it at different temperatures so it was difficult to know what they were saying, so next time I would make sure thay knew what specific temperatures they were going to do so I know what to write down on my results table.
