Biology A level planning experiment of effect of lead ions Essay

Boiling tube Safety hazards / precautions Enzymes – All enzymes are potential allergens so contact an inhalation should be reduced to a minimum. Can cause asthma, cause irritation to nose and eyes do not wallow also if spilt on skin wash off immediately . So gloves and goggles are necessary. And when disposed of it must be diluted in 10 liters of water.

Iodine solution – Vapor is harmful to eyes and when inhaled. Use in a fume cupboard and wear eye goggles. Should again be diluted before disposed of. Avoid contact Witt skin as stains can occur.Lead salts – toxic, do not swallow, avoid inhalation of dusts, use eye protection, dispose of by heavy dilution Justifications for method The equipment used is accurate enough for the experiment by way of measuring and rope adding. I choose the amounts and concentrations specifically so the numbers become easier to work with for example when working out the concentrations also it makes the test more fair if the changes in concentrations change equally each time. I added the Lead nitrate solution and the amylase at the same time so not giving extra time for the lead ions to work (if they have an inhibiting effect).

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And also to avoid starch being reacted before the lead ions are added so it is a fair test. The reason for boiling tube 6 and test tubes F and IF are purely for a controlled experiment to see the pure reaction of Starch solution with the Enzyme Amylase so comparisons can be made. The reason for use of Iodine solution is because of iodine solutions reactions when it comes in contact with starch as it turns Blue / Black. So we can see by darkness of the colour change how much Starch is left in the solution Prediction To make a prediction we need to know a little more about substances we are dealing with.So we can base a prediction on such information. Now we can look at the enzyme it self so we can get an idea of the enzyme structure.

Amylase is a protein, which acts a catalyst, and so is called an Enzyme. Enzymes act as catalysts for many different reactions throughout the body, this is because the heat or energy needed to perform the reaction is too high for the body to sustain so a catalyst is used to lower this energy which is called the activation energy. Amylase is a starch-degrading enzyme. Starch is a mixture of two types of glucose polymers.We can only absorb small molecules so the action of amylase during digestion is essential for survival. All organisms make amylase, which breaks the glucose chain in the centre *1 . We can also use this source to give a thorough explanation of the structure of Amylase *2 lo– The enzyme is a globetrotting. Its single polypeptide chain tot about 4 96 amino acid residues has two SSH (Slothfully) groups and four disulphide bonds and contains a tight bound Ca+.

. 20– Amylase, like many proteins and enzymes, mostly contains wide arrangements of a-helices and b-sheets.The secondary structures are held tightly together by hydrogen bonds. Hydrogen bonds between amino acid residues are especially stable in the hydrophobic interior of the protein, where water molecules do not enter ND therefore cannot compete for hydrogen bonding. 30– Amylase’s tertiary structure consists of one domain of connected a-helices and b- sheets. The sheets and helices are connected by an array of loops and turns of hydrophilic amino acid residues, mostly valise, praline, and glycogen because they produce an abrupt change in direction of the polypeptide chain.By the way of denaturing them changing their shape there fore the substrate will not be able to fit in to the active site.

What causes the Denaturing is the action of the heavy metal ions on specific groups of the protein enzyme itself which is described below Heavy metals, such as lead (BP) and mercury (Hug) exert their poisoning effect by binding to instable or slothfully groups of proteins, including vital enzymes. Once hey bind to an essential functional protein, such as an enzyme, they denature and/ or inhibit it. 8 The sulfured groups are mentioned in the primary structure of the Enzyme Amylase. The action of these bonding to the ions causes the denaturing of the enzyme. From all of this information we can quite accurately make a prediction that the lead ions will more than likely have an inhibitory effect on the Amylase and the effect will be irreversible. As a result from the test I then believe that the higher the concentration of the lead nitrate solution the longer it takes for the enzymes to fully exact the starch solution.I also believe that the detect tot the lead ions (time taken tort starch to react) is proportional to the concentration I. E.

If we double the concentration the time taken will approximately double also. So I would expect a graph of time taken for starch to fully react plotted against concentration of lead ions to look like this: c It would not start from zero because even without an inhibitor it will take some time to react the starch. Also we are able to say from the sources that it will be non-competitive I.



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