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to investigate the volume of amino acid produced from broken down proteins

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BIOLOGY COURSEWORK 2004 Planning Aim: The aim is to investigate the volume of amino acid produced from broken down proteins, from the different concentrations of enzyme protease. By carrying out an experiment, we can find out whether the varied concentration on the enzyme had an effect on the amount of protein broken down, and therefore the volume of amino acid produced. Scientific Knowledge: What are enzymes? Enzymes are proteins that act as catalysts. They speed up the chemical reactions which occur inside living things. Without them, all reactions would be far too slow, and living organisms would not be able to function. Enzymes are extremely efficient at doing their job. Some of the chemical reactions, which take place in our cells, for example in the liver, produce a by-product called hydrogen peroxide. Hydrogen peroxide is very poisonous and it must be got rid of rapidly. Under the influence of an enzyme called catalase, the hydrogen peroxide is broken down into harmless water and oxygen. Catalase acts very quickly - one molecule of it can deal with six million molecules of hydrogen peroxide. One enzyme can be used many times over. This is because a catalyst is a chemical substance that speeds up a reaction but it does not get used up during the reaction. Types of enzymes Enzymes are made inside cells. Once formed, the enzyme may leave the cell and do its job outside. Such enzymes are called extracelluar enzymes. They include the digestive enzymes which brake down food in our gut. Other enzymes do their job inside the cell. They are called intracellular enzymes. Their job is to speed up chemical reactions occurring inside our cells. However, they do not only speed up the reactions, they control them. Effect of temperature on enzymes A rise in temperature increases the rate of most chemical reactions, and a fall in temperature slows them down. ...read more.


The different concentrations of protease were calculated, and then mixed. The protease was mixed in a combi plate. Each well was filled with 0.1 ml of protease enzyme, so if we wanted to mix 40% protease, we would take in 0.04 ml of protease enzyme in the syringe tip and 0.06ml of water. This would then add to 1ml, and it would be squeezed into the well, and it would be 40% concentration. Combi plate diagram: The same process was used to calculate the other concentrations of protease enzyme, and fill the wells in the dishes. When all the wells had been filled with different concentrations of protease, the dishes were placed back into the refrigerator. When they were taken out, the amount of amino acid was measured using a syringe. The amino acid was sucked out of the wells, and the reading on the syringe was taken, then the amino acid was squeezed back into the wells and placed back in the refrigerator. Safety: Protease enzyme is a hazardous and irritant substance. If it manages to enter the eye it can cause permanent blindness. To guard against this, safety goggles are worn. As it is an irritant, if it touches the skin it can cause irritation. Therefore if any protease enzyme ever came into contact with the skin, it was washed off immediately. When the gelatine was mixed with the boiling water, we had to be extremely careful not to spill any of the boiling water and scald the skin. Also, normal laboratory rules applied to the experiment, to guard against any injuries. Fair testing: To ensure that the experiment was a fair test, only a single variable was changed throughout, and the other variables must be kept at a constant during the experiment. For example, the pH or the temperature could not be changed, as this would lead to an unfair test. ...read more.


Also, we can see from the obtaining evidence section that repeat readings were take to increase the accuracy and reliability of the results. Three repeat readings were taken for each concentration, and then an average from that. As there were only two anomalies encountered, more repeat readings were not necessary, as these anomalies were discarded. Improvements that could have been made: A calibrated pipette end could have been used in order to fill the wells with the solution. This would have decreased the chance of the wells overflowing. If more time was available, the plates could have been left in the refridgerator for longer, to prevent the gelatine from melting. However this would have meant that the rate of reaction would have been slowed down significantly. A sharper and more accurate cutting tool could have been used to make the wells exactly circular. An instrument could have been used to suck out any surplus jelly that was left in the wells. Anomalies: As discussed in the errors section briefly, there were a number of reasons why anomalies occured: The gelatine began to melt and the temperature was increased when the gelatine was removed from the refridgerator. This would have increased the amount of amino acid produced. Also when the plates were being carried, the protease sometimes spilt out onto the jelly, which caused further inaccuracy. Due to the slightly different size of each well, there seemed to be a difference in the amount of diffusion, even with using the same concentration of protease. Instrumental error caused inaccuracy, and a main reason why anomalies could have been encountered. We can work out the instrumental error of the syringe by taking the accuracy of its measurement, and dividing it by the number of readings taken. 0.01/5 = 0.02% The syringe was used three times (mixing concentrations, pouring solution into wells, and extracting and measuring amino acid from the wells), so we multiply 0.02% by 3. We therefore obtain a final instrumental error for the syringe as 0.06%. Anraj Rayat Mr. Glanville 11M2 Biology coursework 2004 ...read more.

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