Photosynthesis, Respiration, and Energy

Photosynthesis and aerobic respiration are both processes that are linked to providing plants and animals' energy from the food that they eat. While both of these processes are complex, and similar, they are also both different from one another. One of the biggest differences in these two processes and how they work, is the presence and/or lack of oxygen in the environments of the cells and the cells hosts'. In either case, ATP, the most abundant form of energy for all cells. ATP is created and used as the main source of fuel in living organisms.

Plants use a process in which they take energy form the sun's light to produce sugars, from here with cellular respiration, the energy is then converted into ATP, this process is known as photosynthesis. "The conversion of unusable sunlight into usable chemical energy is associated with the actions of the green pigment chlorophyll" (Farabee, 2007). Through this complex system of turning the sons light into food and energy for the plants, the plants then have waste to get rid of, this waste that the plants let go of, is known as oxygen. "The chloroplasts first convert the solar energy into ATP stored energy, which is then used to manufacture storage carbohydrates which can be converted back into ATP when energy is needed" (Bergman, 1999).

Photosynthesis uses water and releases the oxygen that animals must have in order to survive. By this process as a whole, the use of sunlight, water, carbon dioxide, glucose/sugar, and oxygen are all needed to continue this cycle. Animals breathe the oxygen that the plants put off, and the byproduct of used oxygen from animals is carbon dioxide, which the plants take in as their source of "air" for lack of better terms. Again, this process between plants and animals is much like one hand washing the other.

The human body uses many types of energy in order to function. One of these energy sources is a molecule known as glucose or sugar. The process of the transfer from glucose into cell energy is called glycolysis. "In glycolysis energy is transferred from bonds in the glucose molecule to phosphate bonds in ATP and GTP, and hydrogen bonds in NADH and FADH. Your body then uses the ATP produced to power cellular processes" (The University of Arizona, 1999).

Glycolysis is just one of three stages used in the production of ATP. There is also the citric acid cycle and the electron transport (Bailey, 2012). During the electron transport process/cycle; is where and when oxygen, is of its most importance when producing energy in the cells. Electron Transport requires oxygen directly. "The electron transport "chain" is a series of electron carriers in the membrane of the mitochondria in eukaryotic cells. Through a series of reactions, the "high energy" electrons are passed to oxygen. In the process, a gradient is formed, and ultimately ATP is produced" (Bailey, 2012).

During the absence of oxygen, some organisms use the process of fermentation in order to produce energy. Fermenting organisms produce pyruvates by glycolysis. By this process of fermentation, these organisms are able to produce their ATP. The pyruvate that is created is reduced and not oxidized, which is linked to the oxidation of NADH, which is a must for glycolysis to continue in the absence of oxygen (University of Idaho, 2008).

In anaerobic ATP systems, which is unique to prokaryotic cells, a chemical compound is used called bacteriorhodopsin, this protein allows pigment to absorb light energy, and causes the cell to be able to produce ATP with very little oxygen, by using light as its primary source of fuel (Bergman, 1999).

"The chemical reactions that a cell carries out would normally occur only at temperatures that are much higher than those existing inside cells. For this reason, each reaction requires a specific boost in chemical reactivity. This requirement is crucial, because it allows