There are a whole range of enzymes that catalyse the breakdown of hydrogen peroxide, occurring in both microbial, plant and animal cells. According to the International Union of Biochemistry these are in group 1.11 of “peroxidase” enzymes as “acting on peroxide as acceptor”. The most well-known enzyme that breaks down hydrogen peroxide is called catalase or the full name is hydrogen-peroxide: hydrogen peroxide oxidoreductase (EC number 1.
11.1.6). Catalase breaks hydrogen peroxide down into oxygen and water.
The reaction is 2 H2O2 (+enzyme) = O2+ 2 H2O(+enzyme)Some other information about catalase and peroxidases:* Catalase is a relatively famous enzyme in that it it is an enzyme described as “virtual catalytic perfection” having the highest turnover and catalytic efficiency numbers numbers measured, catalysing over 10 million reactions per second.* In higher organisms catalase is located in organelles called peroxisomes, usually in the liver and kidneys in mammals. Here catalase plays an important role in how the body detoxifies various toxic molecules in the bloodstream, ethanol being one of the important toxic molecules! It also prevents formation of carbon dioxide microbubbles in the bloodstream.* Commercially catalase is used in conjunction with glucose oxidase in the production of dehydrated egg powders.* Peroxidases catalyse these reactions usually with the use of a co-factor; most are “hemoproteins” having a heme group attached to the protein (containing an Fe atom), the same group that is part of hemoglobin that transports oxygen in the bloodstream.* Catalase usually works in conjunction with another enzyme called superoxide dismutase that removes oxygen radicals.The actual organic mechanism of how an enzyme works is probably beyond your course, but if you would like further reading, I would suggest the textbook “Biochemistry” by Voet and Voet or any other good biochemistry textbook, which you could obtain from your local library.Gcse Science Investigation: Heating waterTask:I am going to be investigating the factors which affect how quickly a gas kettle heats (but not necessarily boils) water.
Plan:In this experiment, I am going to be measuring the volume and mass of water (input variable.) My outcome variable will be the temperature. Some variables that may affect the outcome variable are:1) The time of heating.2) The power supplied by the gas.3) The gas supplied to the Bunsen burner.4) The insulation.Prediction & Science:I predict that the larger the amount of the water, the slower the kettle will take to heat. Basically, more mass of water causes the temperature of the water to increase less quickly.
You see, the more mass of water you have, the more particles there are to heat. If you have more particles to heat, the kettle needs more energy supplied to it to heat the water. Some materials need larger amounts of energy than others to produce an increase in temperature. They are much better at storing thermal energy and so have much more to get rid of when they cool down. Notice that water has a particularly high specific heat capacity.
This makes it a useful substance for storing and for carrying energy.Such materials are said to have large specific heat capacities. The specific heat capacity of a material is the energy needed to raise the temperature of 1kg of it by 1 degree centigrade.Then, the total energy is given by:Eh = C.
m.?TMy quantitative prediction is that if you double the mass or the volume of the water, you will half the temperature increase making the same heat at double the amount of particles would result in half the temperature increase. However, there is a limit beyond which this relationship will no longer be true.
Using a Bunsen burner as my source of heat, my apparatus is fairly limited, especially the size of the beaker. The beaker size is restricted to 250cm3. Also, when the water reaches boiling point (1oo degrees centigrade) it cannot possibly get any higher in temperature. This is because the water is boiling.I will make this experiment a fair test by using the same apparatus for each experiment as to be sure not to make any miscalculations.
I will also repeat my experiments at least twice so the benefit of getting an average (mean) result. I will be sure to measure the amounts of water I put into the beaker very carefully to try and make the experiment as accurate as possible. I will also make sure that the thermometer is at room temperature (22 degrees) before starting a particular experiment.
Finally, I will make sure that the Bunsen burner always stays on a blue flame to keep the heat at a constant temperature.Method:Firstly, I set up the apparatus above. I filled my beaker with water and put a lid on it.
Then I lit the Bunsen burner and placed it under the beaker. At that point I started the stopwatch and took the temperature. At the end of the experiment, I measured the temperature again. I will make my measurements as accurate as possible by repeating them and finding an average. I will also use the same apparatus in each experiment and make sure I have measured the amounts of water correctly.
Finally I will make sure the Bunsen burner is always on a blue flame and the thermometer is at room temperature before every experiment.I will make my experiments safe by following the Laboratory safety rules carefully. After all, they’re there for a reason! I will be careful when handling the apparatus before and after the experiments and be cautious that the apparatus may be hot. I will tuck in my tie so it will not get burnt by the Bunsen burner and I will take care not to burn myself or anybody else with the hot water after the experiments.