Concentration Of The Substrate In An Enzyme example essay topic

The Effect of Concentration of Substrate Starch on the Rate of Reaction of the Enzyme Amylase Brief An enzyme is A compound that catalyzes biochemical reactions. Enzymes are proteins, which act with a given compound (the substrate) to produce a complex, which then forms the products of the reaction. The enzyme itself is unchanged in the reaction; its presence allows the reaction to take place. The names of most enzymes end in -ase, added to the substrate (e.g. lactase) or the reaction (e.g. hydrogenate).

Enzymes are extremely efficient catalysts for, and very specific to particular reactions. They may have a non-protein part (cofactor), which may be an inorganic ion or an organic constituent (coenzyme). The mechanism of action of most enzymes appears to be by active sites on the enzyme molecule. The substrate acting with the enzyme changes shape to fit the active site, and the reaction proceeds. Enzymes are very sensitive to their environment-e.g. temperature, pH, and the presence of other substances. Aim: In this experiment, my main objective is to investigate, how the concentration of the substrate starch, effects the rate of reaction of the enzyme amylase.

Therefore i will be testing for how the enzyme amylase is effected by the changes in concentration of the substrate starch while the enzyme is breaking down the starch in to dextrin. This means, i will note the time taken for the solution to clear. Background information: How enzymes work: Enzymes are catalysts. Catalysts speed up chemical reactions that would normally happen very slowly. Enzyme molecules have a complicated three-dimensional shape due to the particular way the amino acid chain that makes up the protein is folded. This tertiary protein structure gives the enzyme its catalytic ability.

A few of the amino acids on the surface of the molecule fold inwards to make a specific indentation, called the active site, into which a particular substrate can fit. Once the enzyme and the substrate are joined they form an enzyme-substrate complex. The formation of an enzyme-substrate complex makes it possible for substrate molecules to be brought together to form a product. The product is released and the enzyme is free again to take part in another reaction. Have a look at the animation to see how this process works.

An enzyme molecule is globular and very large but only a small part of it, the active site, is involved in the reaction. This animation shows how the shape of the active site matches that of the substrate molecule. The substrate molecule fits into the active site and is held there until the reaction is complete. The product is then released and the enzyme is once again ready to take part in the reaction. This is known as the lock and key hypothesis.

The active site has a distinct shape, rather like a lock. Just as only the right 'key' will fit a lock, so only the right substrate has the right shape to fit into the active site. If you increase the concentration of the substrate (the chemicals involved) in an enzyme controlled you will speed up the chemical reaction. The reason for this is as follows: The substrate and the enzyme need to come into contact with each other for a reaction to proceed. When the two meet they join for a brief moment while the reaction is catalyzed, before separating. If there are very few substrate particles in the solution, it will take time for them to bump into an enzyme molecule and therefore the reaction will be slow.

Increasing the substrate concentration means the chance of the collision between a substrate molecule and the enzyme is increased also. A little like packing more people into a room. The more people there are the more people you would bump into. This does not increase indefinitely though. There comes a point when the enzyme is working as fast as it can. As soon as one substrate molecule is converted into the products, another one comes along and takes its place.

The time taken for the enzyme to catalyst the reaction when they come into contact with each other limits how fast it can go. Equipment list: water bath x 1 - to enable the surrounding temperature of the enzyme to be at its optimum. thermometer x 1 - for measuring the temperature of the water bath - making sure it is accurate. test tubes x 5 - for adding the substrate solutions, the enzyme, and the indicator (i.e. iodine). test tube racks - to hold all the test tubes ensuring stability. starch (100%) 1 gram - to make the different concentrations of starch. amylase (100 ml) - to add enzyme to substrate solution. water (200 ml) - to make the different concentrations of the substrate (starch). syringe - for accurate measures of solutions etc. iodine solution (5 drops) - to indicate that starch is present, i.e. turning the solution blue, making it easier for the hydrolysis reaction to be seen (i.e. clearing of solution). black marker - to mark the bottom of the test tube enabling us to see when the solution goes clear. stop clock - to measure time taken for the reaction to take place. beaker - for making the 1% starch solution.