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Our aim is to study the effect of different temperatures and pH on the activity of salivary content, amylase on starch.
Theory
All living beings need energy to survive. It is from the food we consume that we get our energy. We know that the energy we are getting is by the process of digestion that breaks down the complex substance of starch into simpler molecules of glucose, which are further metabolized into CO2 and water through the process of glycolysis. The human digestive tract starts at the mouth and ends at the anus.
In the Beginning
The digestion of the food starts as soon as we put food in our mouth. Our teeth cut the food into small pieces and the salivary glands secrete saliva that mixes with these food materials. The saliva contains an enzyme called salivary amylase which hydrolyses starch into maltose. The complete digestion of starch occurs only in the small intestine by the action of pancreatic amylase.
The activity of enzymes is strongly affected by several factors, such as temperature and pH.
Effect of Temperature
All enzymes are proteinaceous in nature. At a lower temperature, the enzyme salivary amylase is deactivated and at the higher temperature, the enzyme is denaturated. Therefore, more time will be taken by an enzyme to digest the starch at lower and higher temperatures. Optimum temperature for the enzymatic activity of salivary amylase ranges from 32 °C to 37 °C. The optimum temperature means that the temperature at which the enzyme shows the maximum activity. At this optimum temperature, the enzyme is most active and hence, takes less time to digest the starch.
Effect of pH
The optimum pH for the enzymatic activity of salivary amylase ranges from 6 to 7. Above and below this range, the reaction rate reduces as enzymes get denaturated. The enzyme salivary amylase is most active at pH 6.8. Our stomach has high level of acidity which causes the salivary amylase to denature and change its shape. So the salivary amylase does not function once it enters the stomach.
How to test it?
The effect of temperature and pH on the activity of salivary amylase on starch can be studied by using the Iodine test. If we add saliva on starch, the salivary amylase present in saliva gradually acts on starch and converts it into maltose. Starch keeps on giving blue colour with iodine till it is completely digested into maltose. At this point, no blue colour is formed. This is the end point or achromic point.
Learning Outcomes:
- Students understand the process of digestion of starch by salivary amylase.
- Students understand the effect of temperature and pH on the activity of salivary amylase on starch.
- Students do the experiment better in the real lab having gone through the animation and simulation.
PhysioEx 9.0 Ex. 8: Chemical and Physical Processes of Digestion - Review Sheet ACTIVITY1 Assessing Starch Digestion by Salivary Amylase 1. List the substrate and the subunit product of amylase. _starch & maltose respectively__
2. What effect did boiling and freezing have on enzyme activity? Why? How well did the results compare with your prediction?__Boiling caused amylase to be denatured, thus inactivating the enzyme. Freezing has no effect. The function of an enzyme is directly related to its environment, like temperature.__
3. At what pH was the amylase most active? Describe the significance of this result. __ pH 7.0. Amylase is most active in neutral areas, such as the mouth and the small intestine (duodenum).__
…show more content…You can tell because the protein was not digested in tube #1. There was no color change & a density of 0.__ 2. Was your prediction correct about the optimal pH for pepsin activity? Discuss the physiological correlation behind your results. _Yes. The optimum pH matches the pH secreted by gastric glands. Gastric juice is also close to pH 2.___
3. What do you think would happen if you reduced the incubation time to 30 minutes for tube 5? _This would reduce digestion in tube 5.__
A C T I V I T Y 4 Assessing Lipase Digestion of Fat 1. Explain why you can’t fully test the lipase activity in tube 5. _Measurement of lipase activity uses a decrease in pH. Because the pH in Tube #5 is already very low, it is hard to tell if fatty acids are released.__ 2. Which tube had the highest lipase activity? How well did the results compare with your prediction? Discuss possible reasons why it may or may not have matched. __Test tube #1 should have the highest activity because the pH is closest to that of the small intestine.__ 3. Explain why pancreatic lipase would be active in both the mouth and the intestine. _Pancreatic lipase is most active at pH 7.0 The pH of the mouth is 7.0 & the pH of the small intestine is close to 8.0 so the enzyme would function in both places.___4. Describe the process of bile emulsification of lipids and how it improves lipase activity. _Fat globules are separated into droplets by bile salts through an emulsification