Milk
Milk is made up of butterfat globules in a water based fluid as an emulsion. These fat globules are surrounded by a membrane consisting of phospholipids and proteins which act as emulsifiers and keep the individual globules from joining together into larger grains of butterfat. Consequently this protects the fat globules from the fat digesting activity of enzymes and therefore resistant to the pancreatic lipase we will be using. For lipolysis to occur these fat globules need to be disrupted by the work of bile salts to allow lipase to act on them.
Hypothesis
From the research I have carried out I predict that as the concentration of bile salts is increased, so will the activity of lipase on the breakdown of milk and therefore so will the rate of reaction. You will be able to see this activity increase because the rate at which the pH drops will increase because the rate at which the fatty acid are produced from the breakdown of milk will increase therefore lowing the pH. This is because the bile salts emulsify the lipids from large fat globules into smaller droplets providing a larger surface area for lipase to work on.
Consequently because one of the factors affecting enzyme activity is surface area by increasing the surface area you will increase the activity of the enzyme because there will be more successful collision between the enzyme and the substrate at the active site. In this case lipase is a water soluble enzyme and it can only work on the surface of the lipids and when the bile salts are not present it is still able to breakdown the lipids into fatty acids and glycerol but at a very slow rate. When the bile salts are present they increase the surface area available for lipase to work on, increasing the enzymes activity as there will be more successful collisions between the enzyme and the substrate. Therefore by increasing the concentration of the bile salts, more lipid molecules will be emulsified providing the lipase with a bigger surface area for it to work on. However if the concentration of the bile salts continues to increase the rate at which the rate of reaction is increasing will decrease as other limiting factor will begin to have a bigger effect on the rate of reaction. These factor being the variable I have to control during the experiment.
The prediction graph above shows the initial rate of reaction which was calculated by seeing how much the pH dropped in 10 seconds, over the bile salt concentration. As you can see I predict that as I increase the bile salt concentration I believe there will be a proportional increase in the amount the pH drops in 10secs. Because we are only seeing the initial rate of reaction we cannot see any limiting factor as these come into effect much later on during the reaction, this is why I believe there to be a linear relationship between bile salt concentration and initial rate of reaction.
Variables
Preliminary Trials
In our preliminary trials we wanted to see what the optimum conditions for the experiment to take place in were. In finding the optimum conditions it will enable us to get a good set of results which are easy to collect and compare.
Test 1
Our first preliminary test was a test to see the pH of all the solutions we would be using in the experiments. We did because this showed us whether we would need to use the bases or whether the pH of the milk was already provide the alkaline condition needed for lipase to work at its optimum. We found out from this test that milk had a pH of 6.5 so it was slightly acidic therefore we would have to use either sodium carbonate or sodium hydrogen carbonate to neutralise the acid conditions in the milk.
Test 2
The second of our preliminary tests was to test for which base to use either sodium carbonate or sodium hydrogen carbonate and for quantity of these two bases we should use. We decided to carry out this test because my background information informed me that hydrogen carbonate ions were used in the body to neutralise the chyme produced by the small intestines and provided alkaline conditions for pancreatic lipase to work on. Although this was true I also found out that sodium carbonate was a stronger base than sodium hydrogen carbonate from my first test and because of this we would need a smaller volume of sodium carbonate to bring about the same changes as that sodium hydrogen carbonate would bring, making my experiment more efficient. In the experiment we found out that using 2cm3 of sodium carbonate made the pH of the milk increase to pH 9.0 and for the same volume using sodium hydrogen carbonate made the pH of the milk to increase to 7.5. Although the obvious thing to do would be to use sodium carbonate because we would need a smaller volume to about bring the same changes, if you use sodium hydrogen carbonate it would be easier to control the pH of the milk more carefully which makes it easier for us to test which pH to start the experiment from as to determine the optimum pH of lipase which my background showed was between pH 7.5-9. This is because a small amount of sodium carbonate brings about a large pH change so it will be harder to control what amount we would need to put into the milk to make the pH of the milk the pH we want to start the experiment with.
Test 3
Our third preliminary test was to see which pH we should start the experiment from because my background research informed me the optimum pH for lipase was between 7.5-9. In this experiment we used sodium hydrogen carbonate as a base as it was easier to control the pH with. Subsequently when we started the experiment from pH 7 the rate at which the pH dropped seemed to be fast, when we repeated the test for pH 8 it proved to be even faster telling us that this pH was close to the optimum pH of lipase. Finally when we started the experiment at pH 9 we found it was the slightly slower than pH 8 telling us that we had correctly identified pH 8 as lipase’s approximate optimum pH. Therefore in my method I will choose to start the experiment from pH 8 and to achieve this pH we added 3cm3 of sodium hydrogen carbonate to the milk during this experiment, so I will use this volume or however much is needed of sodium hydrogen carbonate in my method to get the pH to 8.
Consequently this makes our results more precise since by starting at the same pH each time we carry out the experiment the enzyme will experience these same conditions making our results more precise.
Test 4
The forth test we carried out was to see what volume of each reactant we were going to use. During this trial we first started by putting in 20cm3 of milk with 20cm3 of bile salts and lipase. The reaction which resulted from putting them volumes was very fast so we decided to reduce the volume of the lipase and bile slats because my background informed me that when digesting fats the body produces as small quantity of lipase and bile salts which are reused. Consequently we decided to use a smaller volume of lipase and bile salts so we used 10cm3 with 20cm3 of milk. This had a very small effect to the rate at which the pH dropped so we were aware that the volume of the lipase or bile salts was not a limiting factor to the experiment. Subsequently I decided to use 20cm3 of milk and 10cm3 of lipase and bile salts during my method as there was no significant change in the rate at which fatty acids were produced there meaning that some of the active sites are unfilled.
Test 5
Our fifth test was to see whether what temperature lipase worked best at because we wanted to provide the optimum condition for it to work under as found in the body. Because our background information and previous knowledge from AS informed us that most enzyme working in the body had an optimum temperature which was the same as the body temperature, we decided to only carry to test for only three temperatures, the body temperature and a temperature above and below this. During the test we found that the biggest pH drop in the smallest amount of time was seen when we carried the test out at 37oC which is the body temperature. Therefore we disregarded doing our actual method with the other two temperatures of 50oC and 30oC as 37 proved to be close enough to the optimum than the other two temperatures.
Test 6
We decided to carry out another test because we were unsure whether a one percent drop in the concentration of bile salts would make such a difference in the results for it to be significant enough to be able to analyse. For this experiment we diluted the bile salts to 4% and to one 1%. The results for the experiment involving the 4% bile salts showed a big enough different compared to the results from the 5% bile salts that allowed us to be able to see the difference clearly and be able to analyse it. Therefore by dropping the concentration of the bile salts by 1% each time it will be enough to see clearly how the concentration of bile salts affect the activity of lipase. As a precaution we decided to also carry out the experiment at the lowest concentration of bile salts which we were going to use which was 1% so we can see whether the experiment still works at such a low concentration. The results from this experiment showed that the experiment worked fine at this concentration of bile salts, therefore in my method I have decided to use 5%, 4%, 3%, 2% and 1% of bile salts concentration.
Control
Our control for this experiment was to use distilled water instead of bile salts to see whether bile salts had an effect on the activity of lipase. My background information showed me that because lipase was a water soluble enzyme it could not act on the inside of the fat globules that the lipids formed therefore there was a smaller surface area for it to breakdown the lipids. However because bile salts emulsify these large fat globules to smaller droplets as these provide a larger surface area for lipase to act on therefore increasing the activity of the lipase. For this experiment we used the same volume of distilled water as we used for bile salts for the previous experiments therefore if bile salts did have an effect on the activity of lipase then adding water instead of bile salts would make to breakdown of milk by lipase slow down or cease to work. Consequently the experiment showed that lipase still functioned without the aid of bile salts although the rate at which the pH dropped was dramatically reduced meaning that bile does actually play an active role and it was not a coincidence that the activity of lipase increased in the presence of bile.
Apparatus
Risk Assessment
- Sodium hydrogen carbonate is an irritant and can cause severe irritation if contact it made with skin or eyes, therefore whilst handling this chemical gloves, goggles and a lab coat should be worn at all times. If contact is made with skin or eyes then rinse the place of contact with cold water for several minutes.
- Lipase can also irritant the skin if contact is made so gloves and goggles should be worn whilst handling it. If contact is made with the skin, the area of contact should be rinsed with cold water.
- Because reactions have to be carried out near a computer, special care should be taken not to spill any of the solutions onto the computer which could cause a fire or break components of the computer
- Glassware should be placed properly on the desk to help minimise the chance of them being knocked down and breaking as a result
- All containers should be labelled to prevent confusion as bases we will use are transparent and so is the distilled water
- Lab coat should be worn to prevent damage of clothing due to spillage and to protect exposed parts of the skin
- Safety goggles should be worn at all times throughout the experiments to prevent any chemicals coming into contact with eyes.
- Long hair should be tied up during the experiments to ensure that it does not get in the way or come into contact with any of the chemicals being used.
- Care should be taken when using glassware to help prevent breakages.
- The thermometers should be handled with care and placed in an appropriate position when not in use to ensure they do not role off the desk.
- When the experiment has been finished all equipment and desk should be cleaned well to remove any risks of other people being accidentally exposed to the chemicals.
- All chemicals should be disposed of in a careful manner and correctly according to what they are. When chemicals are being disposed of down the sink ensure tap is running when putting waste products down there.
- Make sure all gloves and tissue used are placed in the bin when finished with.
Dilution Method
In order to dilute a given solution in a quantitative manner, a known volume of the solution is transferred, via a pipette, to a volumetric flask. Addition of a solvent (usually water) is then added to the flask until the level of the solution reaches the graduation mark on the neck of the flask. The flask is then stoppered (some flasks have plastic caps rather than stoppers) and the contents are then thoroughly mixed.
Dilution to 4%
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Obtain a 100cm3 volumetric flask and move it to your working area
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Obtain a 20cm3 pipettes and move them to your working area
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Obtain a 100cm3 beaker and fill it with approximately 90cm3 of the 5% bile salts solution, then take it to your working area and label it 5% bile salts solution
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Obtain a 100cm3 beaker and fill it with approximately 40cm3 of distilled water, then take it to your working area and label it distilled water
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Using the 20cm3 pipette, suck into the pipette 20cm3 of 5% bile salts solution and then pour the solution into the volumetric flask
- Repeat step 5 another three time until you have 80cm3 of 5% bile salts solution in the volumetric flask
- Using the beaker with distilled water pour the distilled water into the volumetric flask until the solution in the flask reaches the graduation mark
- Put the stopper on the volumetric flask and shake thoroughly for several seconds
- Label the volumetric flask 4% bile salts solution
Dilution to 3%
- Obtain a second volumetric flask and move it to your working area
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Refill the beaker labelled 5% bile salts solution with some more of the 5% bile salts solution until it is approximately 80cm3
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Refill the beaker labelled distilled water with some more distilled water until it is approximately 60cm3
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Using the same 20cm3 suck into the pipette 20cm3 of the 5% bile salts solution and then pour it into the volumetric flask
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Repeat step 4 another two times so that you will have 60cm3 of the 5% bile salts solution in the volumetric flask
- Using the beaker with distilled water pour the distilled water into the volumetric flask until the solution in the flask reaches the graduation mark
- Put a stopper on the volumetric flask and shake thoroughly for several seconds
- Label this volumetric flask 3% bile salts solution
Dilution to 2%
- Obtain a third volumetric flask and move it to your working area
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Refill the beaker labelled 5% bile salts solution with some more of the 5% bile salts solution until it is approximately 60cm3
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Refill the beaker labelled distilled water with some more distilled water until it is approximately 80cm3
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Using the same 20cm3 suck into the pipette 20cm3 of the 5% bile salts solution and then pour it into the volumetric flask
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Repeat step 4 another time so that you will have 40cm3 of the 5% bile salts solution in the volumetric flask
- Using the beaker with distilled water pour the distilled water into the volumetric flask until the solution in the flask reaches the graduation mark
- Put a stopper on the volumetric flask and shake thoroughly for several seconds
- Label this volumetric flask 2% bile salts solution
Dilution to 1%
- Obtain a forth volumetric flask and move it to your working area
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Refill the beaker labelled 5% bile salts solution with some more of the 5% bile salts solution until it is approximately 30cm3
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Refill the beaker labelled distilled water with some more distilled water until it is approximately 90cm3
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Using the same 20cm3 suck into the pipette 20cm3 of the 5% bile salts solution and then pour it into the volumetric flask
- Using the beaker with distilled water pour the distilled water into the volumetric flask until the solution in the flask reaches the graduation mark
- Put a stopper on the volumetric flask and shake thoroughly for several seconds
- Label this volumetric flask 1% bile salts solution
Method
For the following method I believe by using the following bile salt concentrations you will be able to get the best range of data allowing any trends and patterns to be seen clearly as they showed so during the preliminary trails. The concentrations that you should use with this method are:
0% bile salt concentration
1% bile salt concentration
2% bile salt concentration
3% bile salt concentration
4% bile salt concentration
5% bile salt concentration
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Obtain a 100cm3 beaker and fill it with approximately 40cm3 of a pH buffer of pH 7 then take it to your working area and label it pH buffer 7
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Obtain a 100cm3 beaker and fill it with approximately 40cm3 of a pH buffer of pH 4 then take it to your working area and label it pH buffer 4
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Refill the beaker labelled distilled water used in the dilution and fill it with approximately of 40cm3 then take it back to your working area
- Take the pH probe rinse it with distilled water then put it into the beaker labelled pH buffer 7
- Calibrate the pH probe so that it reads this as pH 7 this can be done by pressing the button “set as pH 7” on the pH meter
- Rinse the pH probe with distilled water again and put it into the beaker labelled pH buffer 4 and then see what pH the pH meter reads
- If the pH meter reads pH 4 then you can continue to step 8 if not you must repeat steps 4-6
- Rinse the pH probe with distilled water and put it into the beaker labelled distilled water
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Obtain a 250cm3 conical flask and take it to your working area
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Refill the beaker labelled 5% bile salts with approximately 40cm3 and then take it back to your working area
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Obtain a 100cm3 beaker and fill it with approximately 90cm3 of 3% lipase, then take it back to your working area and label it 3% lipase
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Obtain a 100cm3 beaker and fill it with approximately 90cm3 of milk, then take it back to your working area and label it milk
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Obtain two 10cm3 pipettes, one 20cm3 pipette and a 2cm3 pipette and then take them to your working area
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Obtain a 50cm3 beaker and fill it with approximately 40cm3 of 0.1 sodium carbonate solution then take it to your working
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Take the 20cm3 pipette and suck 20cm3 of milk into the pipette then pour it into the conical flask
- Put the pH probe that was in the beaker labelled distilled water into the conical flask with the milk inside
- Obtain a thermometer and then put it into the conical flask with the milk inside
- Put the conical flask with the milk inside in a water bath to keep the temperature constant
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Take the 2cm3 pipette and suck 2cm3 of the sodium hydrogen carbonate solution and pour it into the conical flask
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Using the same pipette suck another 1cm3 of the sodium hydrogen carbonate solution and pour it into the conical flask
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Take one of the 10cm3 pipettes and suck 10cm3 of the 5% bile salts solution, then pour it into the conical flask
- Using the datadisk 32 program on the computer click record to record the changes in pH
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Take the other 10cm3 pipette and suck 10cm3 of the 3% lipase solution then, pour it into the conical flask
- After 2 minutes click stop to stop recording the changes in pH on the computer
- Rinse the pH probe with distilled water and put it into the beaker labelled distilled water
- Clean the conical flask and rinse it with distilled water then dry it so you can use it again or obtain another clean conical flask
- Repeat steps 15-26 three times to see if results are precise
- Repeat steps 15-27 with different concentrations of bile salts solution
I believe that by using the following method with the correct apparatus my results will be both precise and accurate. This is because in the method above the apparatus I indicate that should be used are very accurate pieces of apparatus such as the pipette which has an accuracy of +/-0.05 which is an accurate piece of glassware. Subsequently by having accurate apparatus it also makes the results more precise as there is less space for deviation of the results as the apparatus are accurate to several decimal places. In addition to this I believe that the procedures I have in my method such as starting from the same pH each time and starting the data logging before the reaction makes the results even more precise since each time we begin the experiment we have the same conditions.
References
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Essential AS Biology – Used for background information on enzymes. The information I obtained from this book, I believe is very reliable and accurate this is because unlike the internet any theories written in science books are checked several times by different scientist before they can be published to make sure they are accurate. In addition to this because it is a book we use during lessons I believe this to be one of the most reliable sources of information I have.
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Mammalian Physiology and Behaviour – Used for background information on bile and digestion of fats. The same can be said about the information I collected from this book, as it to is accurate and reliable. This is because again it is a scientific book checked by many scientist to make sure the theories in the book are accurate and it is also a book we use during lessons
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Biochemistry – Background information on fats. Again the information from this book is accurate and reliable for the same reasons as the books above. This is because before books are published they are checked several times to make sure the theories they say are the accurate and the latest. In addition to this it a book we use during chemistry lesson and because of this it can be seen as a very accurate and reliable source.
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– Used for background information on digestion of fats. The information from this website can be seen as accurate and reliable because it was obtained from a journal written by Department of Pediatrics, Georgetown University Medical Center, Washington, D.C. 2007. Subsequently for this to be published in a journal it must have underwent intense scrutiny from both the university and from other scientists.
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- Used for background information on fats. The information collected from this website is from the University of Bristol a well known and renowned university in England. Consequently the information that is presented on this website must be reliable and accurate since the university must check the information it publishes on its website to make sure its accurate.
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- Used for background information on enzymes. The information I collected from this internet website can be seen as accurate and reliable. This is because even though information on the internet is not always accurate and reliable, I believe the information from this internet encyclopaedia is since it is a well renowned website and the information people publish on it is checked by moderators before it is published on the website.
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– Used for background information on presence of inhibitors. Like before I believe the information collected from this website is accurate and reliable because the website is one of a well known and renowned internet encyclopaedia. Consequently the information it publishes is checked thoroughly to make sure it is accurate and reliable otherwise the website will lose its credibility. In addition to this the information I collected seems to agree with the other sources I read.
Results
By finding the standard deviation of the pH drop for each concentration it tells us the spread of the data around the mean pH drop at that concentration, the higher the standard deviation the higher the data are spread around the mean. As you see in the table above the standard deviation for 0% of bile salts, 0.54, is quite high compared to the others which means that the data collected from experiments using 0% bile salts was not very precise as the data was spread around the mean a lot as the lower the standard the more precise the data is as it is not spread around the mean very much so the data must be same or very close to the mean. Furthermore for the 4% concentration the standard deviation, 0.37, is also quite high and because this was an anomalous result is tells us that some of the data collected for the pH was much lower than the mean pH drop as causing the average pH drop is fall and the standard deviation to also be high.
Analysis
From the results above you can see that as the concentration of bile salts increases the rate of reaction per second also increases but begins to plateau off at higher concentrations. This can be seen as the rate of reaction for 0% bile salt concentration is 0.0064 and this increases to 0.011 for 1%, then 0.014 for 2%, then 0.016 for 3%, then 0.015 for 4% and finally 0.017 for 5%. Consequently this is because as the bile salt concentration increasing the activity of the enzyme also increases as more lipase enzyme will collide successfully with the fat molecules. Furthermore by calculating the gradient between each of the concentrations you can be able to see that the gradient is decreasing as the gradient between 0%-1% is 0.0046 which then decreases to 0.0026 between 1%-2% and continues to decrease to 0.0021 for 4%-5%. Consequently this tells us that the graph is beginning to plateau as the rate at which the rate of reaction is increasing is getting smaller meaning that increasing the bile salt concentration further will have a small effect of the rate of reaction.
Subsequently in my prediction I mentioned that at higher concentrations such as 5% there will be a higher rate of reaction of which there was as it was 0.017 and at lower concentration such as 1% there will be a lower rate of reaction which there was as it was 0.0064. This is because the bile salts emulsify large fat molecules into smaller droplets providing a larger surface area for the enzyme lipase to work on as it is water soluble and not lipid soluble so it can only act on the surface of the fat molecules. As a result this increases the enzymes activity as there will be more successful collisions between the enzymes and the lipid molecules increasing the rate of reaction as surface area is a factor affecting the rate of an enzyme catalysed reaction. Consequently more fat molecules will be broken down be lipase into fatty acids and glycerol lowering the
pH at a faster rate. Therefore we can deduce that bile salts do increase the enzyme lipase’s activity as it increases the rate of reaction.
Eventually, increasing the concentration of the bile salts will have very little effect on the rate of reaction as the enzyme lipase is already working at its optimum, subsequently other limiting factors such as temperature and pH will be affecting the enzymes activity other than increasing the surface area of the lipid molecules. You can see this using the graph or by taking the gradient at each concentration, this shows you that as you increase the concentration the gradient at each concentration becomes lower telling us that the graph is going to plateau at the gradient will eventually become 0 when increasing the concentration of lipase has no effect on the activity of lipase.
In my prediction I did not predict there will be a plateau as I thought that at such low concentration of bile salts the fat molecules would not be fully emulsified for there to be little difference in increasing the concentration. However as you can see in the graph it begins to plateau almost immediately indicating that a small amount of bile salts is able to emulsify a large amount of fat molecules and other factor affecting enzyme activity begin to limit the reaction at higher concentration of bile salts. Subsequently because we used low concentrations of the enzyme lipase I believe this to be the most significant limiting factor the lipase that is used in the body will be at higher concentrations and so will the bile salts because the body is able to reuse both.
Furthermore you can be able to see that even when the concentration of bile salts is 0% the rate of reaction is not 0 as I mistakenly predicted. This is because even though lipase’s activity is reduced it is still able to break down the lipid molecules into fatty acids and glycerol. Consequently I was mistake in thinking that without bile salts there will not be any reaction, as the body only uses the bile salts to increase the rate of reaction by increasing the activity of the enzyme lipase by providing a bigger surface area for it to work on. Therefore the enzyme is still able to work on the lipid molecules but they are so large it can only break it down at certain points which fit into its active site where the enzyme is able to weaken the bonds holding that molecules together at that point such as the induced fit theory indicates.
Conclusion
In conclusion I believe the overall results of my experiment agreed to some extent to what I had to say in my prediction. This is because our results showed us that as you increase the concentration of bile salts the rate of reaction increases. This is because the higher the concentration of the bile salts the higher the rate of reaction as you can see in the graph. Therefore we can deduced that bile salt concentration has an effect on the activity of lipase as all the other variable were kept constant and only bile salts concentration was changed. I believe it affects the enzyme activity as the bile salts emulsify the large fat molecules into smaller ones providing a larger surface area for lipase to work on. Consequently because surface area is a factor that affects enzyme activity by increasing the surface area the enzyme activity will also increase as the chances of successful collisions become greater therefore the bile salts have a direct effect on lipase’s activity as they increase the surface area. Therefore the rate at which the pH drops will increase as lipase breaks the fat molecules into glycerol and fatty acid lowering the pH.
Furthermore because the graph begins to plateau, we can conclude that as you increase the bile salt concentration eventually it will have no effect on the enzyme activity as the enzyme can only help catalyse the breakdown of a set amount of fat molecules. Therefore if you increase the number of fat molecules by emulsifying them into smaller droplets the enzyme will be not be able to catalyse the breakdown off all of them as there are only set amounts of enzyme and they cannot catalyse the breakdown of all the fat molecules simultaneously. Consequently enzyme concentration becomes a limiting factor and if you increase the enzyme concentration the rate of reaction will continue to increase.
Evaluation
Although the results from the experiment agreed with my prediction and my background information there did seem to be an anomalous result for the bile salt concentration of 4%. This is because the rate of reaction for 4% bile salts is lower than that of 3% which is mistaken according to my background information as by increasing the concentration of bile salts the more lipid molecules will be emulsified, providing a bigger surface area for lipase to work on increasing its activity and the rate of reaction. However for this particular concentration it does not seem to follow this trend in increasing rate of reaction as the concentration increases, indicating that either a procedural error or measurement error or both were to blame for this anomalous result. Subsequently I believe that errors in the procedures resulted in the anomalous result the fundamental error being the imprecise method of starting the pH between 8-9. This is because for the experiments we carried out we did not attempt to start at the same pH each time as it was difficult and we did as the method told us a put enough carbonate ions so that the pH was in-between 8-9. Consequently this meant that for some of the experiment the pH might have been at optimum and for other it might have affected the enzyme in a negative way. Additionally because at higher concentration of bile salts, increasing the concentration does not affect the activity much, other limiting factor come into play and because pH is another limiting factor you will be able to see the effect it has more clearly at higher concentration which is what you can see in this case as the concentration of the bile salts is 4%. Subsequently this anomalous result must have resulted from us starting with a higher pH than the other experiments which means the enzyme was further away from its optimum pH 8 making this a limiting factor as it was not closer to its optimum like in the other experiments we carried out.
Because of the many procedural errors in the method, I believe that this affected the accuracy of my results making them slightly less accurate and causing the anomalous which I explained above. Additionally as the majority of measurements I carried out were done with the pipette which is an accurate piece of glassware I believe that they did not have a major effect on the accuracy of the results. Consequently I believe that overall that my results where accurate to some extent as they showed the same pattern as would be seen when increasing substrate concentration in an enzyme catalysed reaction as the fat molecules are being emulsified into smaller droplets by the bile salts increasing the surface area and the substrate concentration.
In conclusion I believe our results are somewhat reliable considering the method, time restraints, and equipment available to us. We were able to answer the question and justify our findings with scientific knowledge, which means that the results were not completely incorrect. There were some anomalies and due to the procedural errors in the method we had. However using computers to minimise the human error, and accurate glassware to measure out volumes this made our results more reliable as these pieces of equipment we used wee more accurate and caused less room for human error. In addition to this the standard deviation which tells us the spread of the data around the mean was low although for some concentration it was higher than others telling us that our results were fairly precise meaning they must be reliable since the experiment was carried out many times by several groups which gave data that was not spread far from the mean. Furthermore because the overall trend of the results shows how at higher bile salts concentration the rate of reaction will be higher, we can therefore conclude that the results are reliable since this trend is similar to the trend shown when the substrate concentration is increased in an enzyme catalysed reaction which is what is occurring in our experiment at by emulsifying the fats into smaller droplets the substrate concentration is also being increased.
Even though our results had an anomalous result, I don’t believe it affected the validity of the conclusion you can draw from the results. This is because the results still show the trend of how increasing the concentration of bile salts increasing the rate of reaction which is scientific knowledge I research for my background suggested. Furthermore by having this trend it shows that bile salts have an effect on the activity of lipase when digesting fats as they seem to increase the rate at which the fats are digested so we can deduce they increase the enzymes activity. The anomalous result we got due to a procedural error is only significant is telling us that there are other limiting factors to the experiment one of them being pH in which case we did not control as effectively causing us to get an error.
Additionally even though the method I used had some procedural errors in it I believe that these errors affected the preciseness of the results more than the accuracy making the results only slightly imprecise as the standard deviation shows since it is low. However by taking the average of these results it made our results more accurate than just using one set of results as this set of results could have been inaccurate. Because of this and the fact that for some of the measurements I carried out I used accurate glassware I can say that my results were valid.