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Design Activity Enzymes

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Enzymes - design Aim: Finding the optimum temperature for decomposing sugar lactose by the enzyme lactase. Introduction: Enzymes, being globular proteins encoded by DNA are very important catalysts for many organisms. They take part in many reactions occurring in live organisms, and although they do not change the structures or amounts of products, they can increase rates of the reactions. It is important as some of the reactions needed to be carried out in an organism quickly to sustain life take too much time, so a catalyst is necessary for them to fasten the reaction. ...read more.


- 700 millilitres of milk - 7 test tubes - Thermometer - Stopwatch - Measuring glass - Lighter or any other source of fire Variables: - independent variable: temperature: 20�C,30�C,40�C,50�C,60�C,70�C,80�C. - dependent variable: how much time is needed by the reaction to occur - controlled variable: the same source of fire, stopwatch, test tubes, milk from the same source, pills of enzyme lactase from the same source - Instructions: 1) Using a measuring glass, pour to every test tube 100ml of milk. 2) Add four pills of enzyme lactase to every test tube. 3) Take first prepared test tube and put the thermometer into it. ...read more.


Note your observations and time for every test tube. Hypothesis: As we know from biology lessons, the activity of enzymes is mostly affected by four main factors: pH, substrate concentration, enzyme concentration and temperature. In this investigation we are going to focus on temperature only and omit the rest of the factors. It is known that most mammalian enzymes have a temperature optimum between 37-40�C. Therefore we can estimate that the milk will be most rapidly digested at the temperature of 40�C. At lower temperatures, the rate of the reaction will be lower, as the higher temperature, the higher rate of the reaction. Whereas at the temperatures higher than 40�C the enzyme may undergo a process called denaturation and will be no longer able to digest milk. ...read more.

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