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Effect of pH on enzyme activity
Pepsin initiates the chemical digestion of
2. Effects of enzymes on a substrate
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Task 1
Extended Experimental investigation
Factors Affecting Enzyme Action
Focus Question:
This lab will be driven by the research question, which pH level has the most successful effect on the activity of the enzyme Pepsin (protease) in the breakdown of the substrate, albumin.
Introduction:
Pearson Baccalaureate: Standard Level Biology Developed Specifically for the IB Diploma describes enzymes as “protein molecules which act as catalysts for reactions. As catalysts, the real function of enzymes is to lower the activation energy of the reactions that they catalyze” (Ward, Tosto, McGonegal, & Damon, 2007). Enzymes are globular proteins that have an overall 3D structure. (George, 2014).
Glands in the mucous membrane of the stomach make and store an inactive protein called pepsinogen. Pepsin is secreted as an inactive form as it is a protein-digesting enzyme and this prevents the gastric gland being destroyed by its own enzyme through auto digestion (Roberts, Reiss, & Monger, 2000).
This inactive protein is kept in its zymogen (inactive) form until it is secreted into the gastric liquids of the stomach, where it is exposed and activated by the hydrochloric acid, and also by pepsin itself as a autocatalytic reaction (Ward, Tosto, McGonegal, & Damon, 2007). Once secreted, the mucus lining inside of the stomach prevents the functioning enzyme from attacking the cells (Roberts, Reiss, & Monger, 2000).
When food is digested, the food is forced down to the stomach by consecutive series of smooth muscle contractions called peristalsis. Once the food is in the stomach, it is held for a period of time in order to mix with the gastric juice (Cleveland Clinic , 2013). Gastric juice is a moist secretion containing hydroc...
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...tly. The enzyme and substrate form a reaction intermediate, and the reaction requires a less amount of activation energy when compared to the reaction between reactions without a catalyst present. (Royal Society of Chemistry, 2004).
The optimum pH of pepsin is 2.0 due to the lock and key theory and the collision theory that is most effectively reactive whilst in this very acidic environment.
This provides the necessary pH that sustains the shape or the properties in its most convenient state so that so that the reaction can be undertaken successfully in a shorter amount of time. Therefore, if the pepsin is placed in various pH environments of 0.5, 1, 1.5 and 2 molar HCL and the substrate, albumin is added to each test tube of pepsin, then the pepsin placed in 2.0 molar HCL will produce the maximum amount of enzyme activity, as it is the optimum pH of pepsin.
The affects of pH, temperature, and salt concentration on the enzyme lactase were all expected to have an effect on enzymatic activity, compared to an untreated 25oC control. The reactions incubated at 37oC were hypothesized to increase the enzymatic activity, because it is normal human body temperature. This hypothesis was supported by the results. The reaction incubated to 60oC was expected to decrease the enzymatic activity, because it is much higher than normal body temperature, however this hypothesis was not supported. When incubated to 0oC, the reaction rate was hypothesized to decrease, and according to the results the hypothesis was supported. Both in low and high pH, the reaction rate was hypothesized to decrease, which was also supported by the results. Lastly, the reaction rate was hypothesized to decrease in a higher salt concentration, which was also supported by the results.
Now the Cheetos have entered the stomach. The process of breaking down carbohydrates has already begun in the mouth and now more chemical and mechanical digestion will take place in the stomach. Once the bolus has entered the stomach, it mixes with gastric juice, starts protein digestion, and absorbs a limited amount. Here the chief cells secrete the inactive enzyme pepsinogen and the parietal calls secrete hydrochloric acid. When mixed together, they create pepsin. The pepsin works to breakdown the two grams of protein present in the Cheetos. Hormones are also present in the stomach and aid in the digestion process. The hormone, gastrin, increases the secretory activity of gastric glands. In the stomach, some salt from the Cheetos is absorbed through the wall. The Cheetos that entered the stomach has no...
The stomach naturally produces acid, which is mainly responsible for food digestion and the destruction of any foreign pathogen or bacteria ingested with food. Acid is secreted by stimulating the partial
The effect of a change in PH on enzymes is the alteration in the ionic
This hurdle is called the activation energy of the reaction. [IMAGE] By decreasing the activation energy, more substrate is changed to product in a certain amount of time. That is, the enzyme increases the rate of the reaction. [IMAGE] The activity of catalase can be measured by finding the rate of which the oxygen gas is released from the breakdown of Hydrogen Peroxide.
Jim Clark. (2007). The effect of changing conditions in enzyme catalysis. Retrieved on March 6, 2001, from http://www.chemguide.co.uk/organicprops/aminoacids/enzymes2.html
The independent variable for this experiment is the enzyme concentration, and the range chosen is from 1% to 5% with the measurements of 1, 2, 4, and 5%. The dependant variable to be measured is the absorbance of the absorbance of the solution within a colorimeter, Equipments: Iodine solution: used to test for present of starch - Amylase solution - 1% starch solution - 1 pipette - 3 syringes - 8 test tubes – Stop clock - Water bath at 37oc - Distilled water- colorimeter Method: = == ==
That means the active site and the substrate should be exactly complementary so that the substrate can fit in perfectly. Once they collide, the substrate and. some of the side-chains of the enzyme’s amino acids form a temporary. bond so that the substrate can be held in the active site. They combine to form an enzyme-substrate complex and the enzyme can start.
In this experiment as a whole, there were three individual experiments conducted, each with an individualized hypothesis. For the effect of temperature on enzyme activity, catalase activity will be decreased when catalase is exposed to temperatures greater than or less approximately 23 degrees Celsius. For the effect of enzyme concentration on enzyme activity, a concentration of greater or less than approximately 50% enzymes, the less active catalase will be. Lastly, the more the pH buffer deviates from a basic pH of 7, the less active catalase will be.
...on dioxide, within the body, affecting the pH balance of the blood. This will then affect proteins within the body, being known as enzymes, which can only function if their surrounding environment is in balance. Any alteration to this environment, will prevent the enzymes from functioning effectively.
...ve eaten, to break down the food into a liquid mixture and to slowly empty that liquid mixture into the small intestine. Once the bolus has entered your stomach it begins to be broken down with the help of the strong muscles and gastric juices which are located in the walls of your stomach. The gastric juices are made up of hydrochloric acid, water, and mucus- and the main enzyme inside of your stomach is what is known as pepsin, which needs to be surrounded in an acidic setting in order to do its job, that is to break down protein. Once the bolus has been inside of your stomach for long enough it begins to form into a liquid called chyme, and what keeps the chyme from flowing back into our esophagus are ring shaped muscles known as sphincters located at the beginnings and ends of the stomach and they have the task of controlling the flow of solids and liquids.
Once in the stomach, the glands that are there begin to secrete enzymes and a mucous that help to protect the stomach from its own acids. While this is being done, the muscles of the stomach are contracting. This causes the food to be turned and moved all throughout the stomach. This process turns the food into chyme, which is just a liquefied version of the food that was first taken...
The exocrine function of the pancreas is that it produces enzymes that aids in the digestion of food. There are three important enzymes that are crucial in helping with digestion. The first digestive enzyme is amylase. Amylase function is to break down carbohydrates. The amylase enzyme is made in two places: the cells in the digestive tract that produces saliva and the main one specifically found in the pancreas that are called the pancreatic amylase (Marie, Joanne; Media Demand, “What Are the Functions of Amylase, Protease and Lipase Digestive Enzymes”). The amylase in the pancreas passes through the pancreatic duct to the small intestines. This amylase in the pancreas completes the process of digestion of carbohydrates. Consequently, this leads to the production of glucose that gets absorbed into the bloodstream and gets carried throughout the body. The next enzyme that aids in digestion of food is protease. While amylase breaks down carbohydrates, protease breaks down protein. Protease breaks down protein into the building block form of amino acids. The three main proteases that it produces are: pepsin, trypsin and chymotrypsin (Marie, Joanne; Media Demand, “What Are the Functions of Amylase, Protease and Lipase Digestive Enzymes”). Pepsin does not occur in the pancreas but it is the catalysis in starting the digestion of proteins. Trypsin and chymotrypsin are the two proteases that occur in
Without enzymes, reactions wouldn’t occur and living organisms would die. For instance, the enzyme in the stomach breaks down large molecules to smaller molecules to absorb nutrition faster. Researchers experimented with enzyme activity with a potato extract. Researchers will test enzyme activity by increasing and decreasing pH levels, lowering and increasing temperature, and substrate concentration effects. In the first experiment, researchers hypothesized whether different pH levels would change how much Benzoquinone are created and how will the enzymes function in neutral pH levels than higher and lower levels. Researchers used potato extract and different levels of pH to test their hypothesis. In addition, researchers questioned at what temperature does the greatest amount of potato extract enzyme activity take place in. Researchers then hypothesized that the results would indicate the greatest amount of potato enzyme activity level will take place in room temperature. In this experiment, researchers used potato extract and different temperature levels to test the hypothesis. Moreover, researchers wanted to test the color intensity scale and how specific catechol oxidase is for catechol. In this experiment, researchers used dH2O, catechol solution, hydroquinone, and potato extract. Lastly, researchers tested the substrate concentration and how it has an effect on enzyme activity. In this experiment researchers used different measurements of catechol and 1cm of potato extract. Researchers hypothesized that the increase o substrate would level out the enzyme activity
It is then secreted within the small intestine where it helps to break down ethanol, fats and other acidic wastes including ammonia, into harmless substances.