Plant Mitochondri Cytochrome Oxidase And The Cyanide Insensitive Alternative Oxidase Essay

The main function of the mitochondria is to convert fuel into a form of energy the cell can use. Specifically, the mitochondria is where pyruvate --derived from glucose-- is converted into ATP (Adenosine triphosphate) through cellular respiration. Cellular respiration involves four stages: glycolysis, the grooming phase, the citric acid cycle, and oxidative phosphorylation. The final two stages listed occur in the mitochondria.

Both photosynthesis and cellular respiration are the main pathways of energy transportation in organisms. However, the reactants and the products are exact opposites in photosynthesis and in cellular respiration.

The last step of cellular respiration is the Electron transport chain (ETC). The ETC takes place in the inner mitochondrial membrane. Electrons from Hydrogen are carried by NADH and passed down an electron transport chain to result in the production of ATP. Results are the production of ~32 ATPs for every glucose. Oxygen, which is the final electron receptor, finishes the process by creating a water molecule and combining the remaining hydrogen molecules. Oxygen is the final electron receptor. Without it, the process cannot be complete (Cellular Respiration, 2004). The waste products of cellular respiration are CO2 and H2O that are the same incrediants used in photosynthesis. Plants store chemical energy by photosynthese and then harvest this energy via cellular respiration.

Assay of succinate dehydrogenase of after isolation of mitochondria in Cauliflower (Brassica oleracea) using differential centrifugation.

The role of an enzyme is to catalyse reactions within a cell. The enzyme present in a potato (Solanum Tuberosum) is catechol oxidase. In this experiment, the enzyme activity was tested under different temperature and pH conditions. The objective of this experiment was to determine the ideal conditions under which catechol oxidase catalyses reactions. In order to do this, catechol was catalyzed by catechol oxidase into benzoquinone at diverse temperatures and pH values. The enzyme was exposed to its new environment for 5 minutes before the absorbance of the catechol oxidase was measured at 420 nm using a spectrophotometer. The use of a spectrophotometer was crucial for the collection of data in this experiment. When exposed to hot and cold temperatures, some enzymes were found to denature causing the activity to decrease. Similarly, when the pH was too high or low, then the catechol oxidase enzyme experienced a significant decrease in activity. It can be concluded after completing this experiment that the optimal pH for catechol oxidase is 7 and that the prime temperature is 20º C. Due to the fact that the catechol oxidase was only tested under several different temperatures and pH values, it is always possible to get a more precise result by decreasing the increments between the test values. However, our experiment was able to produce accurate results as to the

vulgaris plants, via the formation of a standard curve prepared using varying concentrations of bovine serum albumin (BSA) solution. Following absorbance readings of the various BSA solutions, they were plotted against their concentrations providing an indirect measure for determining protein concentrations of the plant samples within the assay tubes, and through further calculations the sample protein concentration. The mean protein concentration for the control group was calculated to be 3.34 ± 1.30 mg/mL, while the mean treated group concentration was 2.01 ± 1.26 mg/mL. These results similarly like the chlorophyll results correlate with the literature articles, as a reduced protein content within the Paraquat treated plants can be expected to some extent (Chia et al., 1981). This reduction in protein concentration is the result of those superoxide anions produced by Paraquat, disrupting the chloroplast membranes and allowing for intracellular components including some proteins to leak out, hence the decrease in protein concentration in comparison to the non-treated plants (Qian et al., 2009). A slight outlier may exist within the treated groups protein concentrations as one of the groups provided a negative value for protein concentration which is not valid, but even after exclusion of that data value, results are still supportive of the expected outcome. Though these results support the claim of Paraquat toxicity causing membrane deterioration and leakiness, protein concentration values are rather more purposeful when used to analyze malondialdehyde (MDA) values on per mg of protein

Cellular respiration is bioenergetic process, meaning that it is governed by enzyme activity. Referring to what was previously learned about enzymes, it is known that enzyme-substrate reactions can

oxidation in the mitochondria within each cell. Carbohydrates, proteins, and fats can all be metabolized as

Glycolysis is followed by the Krebs cycle, however, this stage does require oxygen and takes place in the mitochondria. During the Krebs cycle, pyuvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. This begins when pyruvic acid produced by glycolysis enters the mitochondria. As the cycle continues, citric acid is broken down into a 4-carbon molecule and more carbon dioxide is released. Then, high-energy electrons are passed to electron carriers and taken to the electron transport chain. All this produces 2 ATP, 6 NADH, 2 FADH, and 4 CO2 molecules.

Turnips and horse radish roots are rich source of this enzyme. In this experiment, we would carry out a reaction between hydrogen peroxide and guaiacol which is colorless dye, using peroxidase as a catalyst, to produce water and an oxidized form of guaiacol which is brown. The formation of brown color would serve as an indicator that the breakdown of Hydrogen Peroxide took place. The enzyme activity would be directly proportional to the brown color intensity. The color intensity would be measured using a spectrophotometer and standardized to find the corresponding concentration for each absorbance unit.

Cellular respiration and photosynthesis share many similarities in structural components and processes, such as the fact that both derive energy from electrons as they pass through a chain. With the use of electron transport chains, both processes move hydrogen ions across a membrane to form a chemiosmotic gradient. Both systems use this gradient to move hydrogen ions through the membrane passively and into an ATP synthase molecule, which yields ATP molecules. We see the intermediate molecule G3P in cell respiration and photosynthesis, which goes on to form glucose or other complex compounds. Both systems share unique and similar characteristics that make life possible for both plant and animal cells.

Mitochondria of B. oleracea florets were used because they do not contain chloroplasts (which contain SDH too) and both would be present in the pellet after differential centrifugation (Willeford et al., 1989); thus florets were used so that the source of electrons could be related to the activity of mitochondrial SDH, and isolated by mechanical disruption of the plasma membrane to release subcellular compartments, filtered (to remove unfractured cells and extracellular material) and then suspended components were separated from the mitochondria by differential centrifugation. Succinate was reacted with SDH, and its activity was quantified by DCIP and spectrophotometry to establish the rate of SDH enzyme activity. Three fractions (mitochondria-free (MFF), mitochondria (MF) and mitochondria with malonate (MF-M) fractions) and a control were prepared, and assay buffer was added to each of the four samples to provide a favourable environment to maintain the mitochondrial structure and optimal SDH activity (Schneider and Hogeboom, 1951). The rate of SDH activity was indirectly measured by a standard curve of the absorbance against concentration of DCIP (a colorimetric test). The rate of DCIP absorbance correlated with the rate of change in DCIP concentration (also related to the DCIP’s electron acceptance rate) and was presumed to indicate the rate of SDH activity.

The enzyme catechol oxidase, extracted from masticated potato (Solanum tuberosum) lowers activation energy, as it is a catalyst. This enzyme can react with catechol to produce benzoquinone and water. Catechol oxidase is tested against a multitude of phosphate buffers, acidic, neutral and basic pH values, and chilled temperatures to hot temperatures. The purposes of these testes were to determine the optimal temperature and pHs at which catechol oxidase performs at. The method to measure results was the usage of a spectrophotometer (Vernier Spectrouis Plus). The spectrophotometer measures the absorbance levels of the pigment excreted when catechol oxidase undergoes a reaction. The high the absorbance, the more products produced and vise versa. The highest absorbance for the catechol oxidase submitted to different temperatures measured an average 0.6018 nm, when at 20 C. The highest absorbance for the catechol oxidase submitted to different pH values measured two averages of 0.658 at pH 6 and 0.6464 at pH 7. The conclusion taken from the available data explains that the optimal pH for catechol oxidase was between pH 6 and 7 and the optimal temperature was at room temperature at 20C.

In plants, alae and other aerobic organisms, oxidative phosphorylation (OXPHOS) and photophosphorylation are the two most important energy transductionsliving organisms. These two processes together account for most of the ATP synthesized these living organisms. In eukaryotes, OXPHOS occurs in mitochondria, generate ATP from ADP and Pi by involving the reduction of O2 to H2O with electrons donated by NADH and FADH2. Photophosphorylation occurs in chloroplast or photosynthetic organisms which capture the energy of sunlight and use it to oxidise the H2O to O2 with NADP+ as electron acceptor to make the ATP. Despite their differences, these two highly efficient energy-converting processes have fundamentally similar mechanisms.

Cellular respiration is a procedure that most living life forms experience to make and get chemical energy in the form of adenosine triphosphate (ATP). The energy is synthesized in three separate phases of cellular respiration: glycolysis, citrus extract cycle, and the electron transport chain. Glycolysis and the citric acid cycle are both anaerobic pathways because they do not bother with oxygen to form energy. The electron transport chain however, is aerobic due to its use of oxidative phosphorylation. Oxidative phosphorylation is the procedure in which ATP particles are created with the help of oxygen atoms (Campbell, 2009, p. 93). During which, organic food molecules are oxidized to synthesize ATP used to drive the metabolic reactions necessary to maintain the organism’s physical integrity and to support all its activities (Campbell, 2009, pp. 102-103).