Digestion of Starch

Digestion of Starch

AbstractThe human body consists of tiny living units called cells. These cells carry out various physiological processes that are essential for the survival of those cells; hence the whole body. Among these processes are biochemical reactions that make available nutrients in forms which are readily utilized in the body, i.e. digestion of food. Food consists of various components such as starch, proteins, lipids, minerals, and vitamins. These components are broken down (through digestion) by the cells such that they are readily utilized for various purposes such as providing energy, building up of cellular structures as well as facilitating other physiological functions. Digestion of food is made efficient by molecules known as enzymes that speed up rates of biochemical reactions so as to provide efficiency in making available of the said nutrients. These enzymes operate efficiently under optimum conditions in which the intracellular environments provide such as the pH and the temperature of the environment in which the cells are found, among others. When these conditions are inhibited, or otherwise interfered with, several aspects of these enzymes are altered in ways that make the said enzymes non-functional. An experiment is carried out in a laboratory simulating the human cell to understand further the consequences of changing one of these cellular environmental conditions (temperature) affecting the physical; hence the working properties of the enzyme that catalyzes digestion of starch.

Introduction
Digestion of starch is a biochemical process that occurs in the human body, more specifically, the human mouth, as does other metabolic processes at the same time. An experiment simulating the human body conditions is carried to determine the rate of digestion of starch.
Hypothesis
In a given time, the rate of digestion of starch by enzyme amylase increases with the increase of temperature until the optimum temperature is obtained; after which, the digestion rate decreases.
Procedure
Two sets of 5 tubes are set aside. One set is filled with 7 ml of 3 different solutions (1 ml of 6.8 pH buffer, 2 ml of 1% starch solution and 4 ml of distilled water) while the another set is filled with only 1 ml of enzyme amylase. Five water baths of different temperatures- ice (00C), 200C, 400C, 600C, and 800C are assembled, and two tubes, one from each set is placed in each water bath for 5 minutes to allow the solutions to warm up to the respective temperatures. The two test tubes of each water bath are mixed (one with % starch, water, and buffer and the second with amylase) and this is designated the reaction time. After the combination of the two tubes, a single drop of the reaction is taken and placed every 10s on a testing plate with two drops of iodine. A drop of the reaction of every 10s is taken and measured up to ten minutes for each of the reactions.
When starch is present, iodine will change color into dark blue, while no color change means that starch is no longer present.
Results
There was digestion of starch in:
520s for reaction in 00C
410s for reaction in 200C
320s for reaction in 400C
More than 600s for reaction in 600C where there was no observed colour change for ten minutes.
More than 600s for reaction in 800C where there was no observed colour change for ten minutes.
Inference
The rate of starch digestion is slower at lower temperatures and gradually speeds up as the temperature is increased. As the temperatures reach levels of 400C (which is close to the normal human body temperature-370C), the rate of starch digestion is at its peak, in that digestion of starch occurs in the shortest time possible. This rate gradually starts to decrease as the temperature gradually supersedes the optimum temperature. In this experiment, evidence of starch digestion is characterized by a change of iodine color from brown to dark blue. Where digestion of starch has not occurred, iodine will retain its original color. This process undergoes through a controlled environment such as that of required optimum pH level.
Discussion
At lower temperatures (such as at 00C), the starch molecules are heavy and have less kinetic energy and therefore move into the active site of amylase slowly. This, therefore, means that digestion of starch will occur at a slower pace. When the temperature is increased, there is increased the kinetic energy of substrate molecules which thus move at a quicker pace into active sites of amylase. Hydrolysis of starch is speeded up and is rapidly continuous as starch molecules occupy active sites of amylase, are digested, move out, and other starch molecules move in to replace the digested ones just as quickly. This is a continuous cycle until all starch is digested. At optimum temperatures, as in our experiment; 400C- starch molecules have obtained maximum kinetic energy to move into active sites of amylase while its shape is stable.
As the temperatures begin to exceed 400C, the shape of amylase starts to change. This is called denaturisation. High temperatures change the physical shape of enzymes as the sequence of amino acids (building blocks of proteins) is altered. This is in such a way that the grooves i.e. the active sites of the enzyme are changed that the substrate molecules cannot fit in those active sites anymore, much more like when a lock (active site of the amylase) is damaged, a key (starch molecule) cannot fit into the lock to open a door (digestion to occur).
Beyond 400C, as in at 600C and 800C, denaturisation of the enzyme amylase has occurred, which means that its shape has been changed. This means that the active site where the starch substrate can attach is no longer available and therefore the rate of reaction is slowed down incredibly to a stop.
Conclusion
Enzymes are proteins, which all have different chemical and physical properties. These structural features of proteins, hence enzymes are delicate in nature and can only be preserved in well-maintained environments of the required optimal conditions; such as the correct temperatures, pH among others. When these conditions are not met, the normal functioning of the enzyme amylase is inhibited. When these conditions are superseded, the structure (i.e. the shape of the enzyme) and chemical properties of the enzyme are altered. Hence amylase ceases to function as it would normally do. The human body is a balanced system of controlled homeostatic environment that carefully balances all the optimum conditions necessary for the different biochemical processes occurring in the body cells. Disruption of these processes or otherwise these environmental conditions infers abnormal functioning of the body, such as is the case with effects of diseases in the body.