Biology Open-Ended Investigation

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Biology Open – Ended Investigation

Assessment Task 1

Weighing: 20%

Due Date:
• Part A – Term 4, Week 7 Monday, 19th November, 2012 • Part B – Term 4, Week 7 Friday, 23rd November, 2012

Shamiran Khamis

Part 1 – Scientific Report

Title: Factors Affecting Enzyme Action

Introduction: Enzymes are catalysts, because they control the rate of the reaction that helps chemical reactions work properly within living organisms. They are specialised proteins that have a unique shape and chemical composition that creates an active site for connection between the enzyme and substrates. The substrate molecules bind to the active site, inducing a temporary change in the shape of the enzyme known as induced fit. Enzymes catalyse and modify the rate of biomechanical reactions without becoming a part of the product of reaction. Like all proteins, enzymes are made in the ribosomes by linking together amino acids from the cytoplasm. Their action is dependent upon their ability to fit with the molecule reactants; otherwise the reaction will not proceed. For example, study from previous experiments demonstrates that the maltose present will not turn into glucose until it enters the intestine (different catalyst). There are diverse types of enzymes that work best under certain optimum conditions including temperature, pH and substrate concentration. Enzymes can be used more than once and are very important to cell functioning; therefore only small quantities of them are required in the cell. The effect of temperature on enzyme activity is; lower temperatures (0 C) will cause the substrates to move at a significantly slow speed to collide and react with the enzyme therefore very little product will be produced, where as too high of a temperature (100 C) will cause denaturing in the enzyme and very little product will be produced, and lastly room temperature (37 C) will provide the most product of the temperatures being tested. In the presence of starch iodine turns blue/black in the temperatures of 0 C and 100 C (sometimes present in 37 C temperatures) and if no starch is present it is a pale yellowy-brown colour.  Iodine can therefore be used to monitor the breakdown of starch into sugar.  When the iodine no longer changes colour, you know all of the starch has been broken down. Lastly in the presence of maltose, the benedicts solution turns blue at 0 C and 100 C temperatures. Where as the salivary amylase catalyzes the breakdown of starch to maltose and it turns red.

Formula: Starch Disaccharide Monosaccharide


Enzyme activity occurs in a specific temperature range (37 C) in order to help chemical reactions work properly in living organisms. Aim: To test the effect of temperature on the ability of salivary amylase to catalyse the breakdown of starch to maltose.

• Clean test tubes 6x (3x for Benedict’s and 3x for Iodine) • Test tube rake 1x
• Glass rod
• 250mL Beaker 3x (big enough to act as water baths for test tubes) • Bunsen burner 2x
• Tripod 2x
• Gauze mat 2x
• Thermometers 3x
• Test tube holder 1x
• Ice cubes
• Starch solution
• Benedict’s exp
• Matches
• Kettle for boiling hot water
• Test tube pegs 6x
• Pipet 1x

Step 1: Set-up equipment as drawn below
Step 2: Place all 6 test tubes in the test tube rack holder and number them from 1-6 Step 3: Dribble 1cm of saliva into each of the four test tubes Step 5: Perform the following the test tubes:-
1. Test tube 1-37 C
• Put test tube 1 (benedict’s) and 4 (iodine) into a beaker of water at 37 C and keep at that temperature in a water bath Add about 10 drops of starch solution • Keep at 37 C for 15 minutes

• Test the contents of the test tube for sugar, with iodine • Record the colour...
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