The equation of the reaction in this experiment is 2H2O2+ catalase= 2H2O + O2.Catalese is an enzyme in the liver that break downs harmful hydrogen peroxide into oxygen and water, (Science Buddies, 2012). When catalase added into the hydrogen peroxide, it reacts rapidly and oxygen gas bubbles escape and foam created. Catalase rapidly destructs hydrogen peroxide in two steps. Firstly, a hydrogen peroxide molecule binds and broken apart. One oxygen atom is extracted and attached to an iron atom, and the rest is released as toxic water. The second hydrogen peroxide molecule which binds is broken apart and the pieces are combined with the iron-based oxygen atom, releasing water and oxygen gas, the reaction is assisted by the histidine and asparagine amino acids. (David Goodsell, 2004).
The plant or animal organelle involved in this experiment is peroxisomes. Peroxisomes is a small, membrane-enclosed organelles present in the cytoplasm of many cells, which contains the reducing enzyme catalase that involved in a variety of metabolic reactions. Peroxisomes play a key role in the oxidation of specific biomolecules to produce hydrogen peroxide. In animal cells, peroxisome acts an important role in detoxification by decreasing their rate of oxygen. The long chains of fatty acid is break down by peroxisome through oxidation and produced hydrogen peroxide. Harmful hydrogen peroxide will be decomposed by peroxisomes contain catalase enzyme that act as a catalysts and quickly convert into water and oxygen. After detoxification, the harmless water and oxygen is released back into the liver cell. In the experiment, liver that contain harmful hydrogen peroxide is decomposed by catalase in peroxisome and convert into hydrogen and water. When glowing splinter added into the boiling tube, the glowing splinter rekindled with bright red flame which means oxygen is released. In plant cell, peroxisome plays an important role in converting fatty acids to sugar and chloroplasts in photorespiration .During photosynthesis and photorespiration, hydrogen peroxide is produced generally.( Acta Biochim Pol. 2007). So, catalase enzyme in peroxisome is required to break down the hydrogen peroxide.
Pulping the liver has increase the rate of reaction in the experiment. When the liver was pulped, the total surface area of the liver increased. Larger area of liver was exposed to react with hydrogen peroxide. The frequency of effective collisions between the enzyme catalase and the hydrogen peroxide molecules increased. Hence, when the total surface area of enzymes increased, the rate of reaction between catalase enzymes and hydrogen peroxide increased.
There is no reaction occurred between the liver cells and hydrogen peroxide when the liver is boiled in 95?C. The catalase enzymes are made up of protein. The molecule will started to vibrant violently when heated the enzyme with high temperature .When the temperature reached the optimum temperature of enzyme, weak bonds like hydrogen bonds and hydrophobic interactions will break first and followed by the stronger bond, ionic bonds. The enzyme three dimensional structures including its active site will be altered. Enzyme loses its catalytic functions are said to be denatured. When the structure of the enzyme is fully destroyed, no catalysis takes place. Therefore, when glowing splinter is added into the test tube, there is no obvious observations occur.
The reaction between the fresh liver and hydrogen peroxide is very rapid and produced high amount of large bubbles , the glowing splinter is rekindled with bright reddish flame while the reaction between the fresh potato cubes and hydrogen peroxide is slow and produced small amount of small bubbles , the glowing wooden splinter do not rekindled. The difference between the reactions with fresh liver and with fresh potato cubes is the peroxidase in fresh liver is more than the fresh potato cubes. It is because in liver cell, the peroxidase plays a critical roles to detox the harmful hydrogen peroxide into hydrogen and water. In potato cells, do not have a lot of oxidation reaction or breaking down process, therefore have lesser amount of peroxisomes.
Boiling the liver and heating up the manganese dioxide produce different result and observation. When boiling the liver at 95?C, the temperature has reached the optimum temperature of the enzyme. Therefore, the enzyme is denatured and loses its catalytic function to binds to the active sites of products. Whereas, boiling the manganese dioxide with 95?C will not affect the result. It is because manganese dioxide is an inorganic catalyst, the high temperature did not change the structure and shape of the manganese dioxide molecule. So heating up the manganese dioxide with high temperature will not denature the catalytic function.