Week_3_Sci_230_Photosynthesis_and_Cellular_Respiration

Assignment: Photosynthesis and Cellular Respiration Energy Energy may be best defined as anything that produces work and may be seen in many forms. This week’s reading focused on photosynthesis which plants convert energy from a light source (sun) into organic molecules used as food and cellular respiration in which cells gather energy from metabolizing plant molecules. As the definitions would indicate, cellular respiration and photosynthesis are a form of energy, but within these forms one will find other energy processes taking place. In order to better understand these processes I will list them under their prospective source and give a brief definition of their purpose. Within photosynthesis are the energy forms: Light-dependent reaction is the first stage of photosynthesis requiring light. Light energy is absorbed by chlorophyll which then undergoes a chemical reaction producing adenosine triphosphate (ATP) (Pruitt & Underwood, 2006, pg. 301-303). The Calvin-Benson Cycle, also known as light-independent reaction, is the second phase of photosynthesis and does not require light. During this phase carbon dioxide, obtained from the air, is used to produce glucose (Pruitt & Underwood, 2006, pg. 304-305) Within cellular respiration are the energy forms: Glycolysis, the first stage of cellular respiration, is the metabolic process that converts glucose (done through several steps) into pyruvic acid (Pruitt & Underwood, 2006, pg. 290-291). The Krebs Cycle is the second stage and “central pathway in cellular metabolism.” The cycle is a cellular level conversion process that produces high-energy phosphate compounds which serves as a source of energy. It is also the link between aerobic and anaerobic phase that increases ATP synthesis (Pruitt & Underwood, 2006, pg. 292-293). Electron transport system is the third and final stage of cellular respiration. The system is a series of reactions in which electrons and protons are taken from each hydrogen element of NADH and FADH. The electrons transport the protons across the mitochondria’s membranes initiating ATP synthesis. *Note: In plants this process takes place in the thylakoid membrane (Pruitt & Underwood, 2006, pg. 294-296). What Is an Energy Wavelength' An energy wavelength is the distance between each adjacent wave crest. It is the measurement of the frequency of the wave being studied. The similarity between the wave in the ocean and any other wave is they both exhibit a frequency and amplitude. The difference is between any wave form is its frequency, shape, and amplitude (Pruitt & Underwood, 2006). It is simple to see what makes each of the above stages a form of energy; they each have to go through a process of chemical changes to reach their prospective result. This would be known as work in progress; work produces energy. Are there other forms of energy' Yes, however they are too many to list, but here a few examples taken from this week’s reading; electromagnetic energy, metabolism, kinetic energy, potential energy, aerobic, and anaerobic energy. Chloroplasts and Mitochondria Unlike the mitochondria, chloroplast is found only in plants and some protists and is where photosynthesis begins. The chloroplasts and mitochondria may have several similarities in structure such as they both contain DNA, ribosomes, and a double membrane. However, there is a major structural difference between chloroplasts and mitochondria. Chloroplasts contain a third membrane called the thylakoid membrane. It is here (thylakoid membrane), as seen in the inner membrane of the mitochondria, that electron transport takes place (Pruitt & Underwood, 2006). The major similarity in function is both chloroplasts and mitochondria are responsible for changing one form of energy into another form energy. They both act as power plants that fuel energy in order to sustain life. If one was to study the many similarities of both organelles, they may, as I have, theorize they are both of the same origin and were able to survive evolution due to endocytosis. The Calvin-Benson cycle of photosynthesis is also known as light-independent because this cycle does not need light for photosynthesis to take place. It is the second phase of photosynthesis in which carbon dioxide, obtained from the air, is used to produce glucose (Pruitt & Underwood, 2006, pg. 304-305). Cellular Respiration: Lactic Acid and ATP When the body has reached its maximum demand on the lungs and circulatory system, limiting the amount of oxygen available, lactic acid fermentation begins. Lactic acid is a product of pyruvate and does not produce energy. However, its purpose is to change NADH into NAD+ and regenerate it to aid, through anaerobic process, the process of glycolysis. The production of ATP in the electron transport differs from glycolysis and the Krebs cycle is; glycolysis is the breakdown of carbon and phosphoglyceraldehyde into pyruvates. This produces four ATP’s and two NADH, but two ATP’s are used in the process leaving only two ATP. The Krebs cycle converts pyruvate into acetyl CoA which produces two ATP’s, eight NADH’s and two FADH2. This cycle is repeated for each glucose molecule, therefore producing the net amount of two ATP, two FADH2, six CO2, and eight NADH. It is in the electron transport system (ETS) where the majority and last amount of ATP is produced. The ETS takes H+ from FADH2 and NADH and is broken down into protons and electrons. The electrons enter the ETS and travel through a complex system which the energy from the protons are transferred into the space between the outer and inner membrane of the mitochondria where energy is stored as proton gradient. For ATP to be released a process called mitochondrial ATP synthesis takes place, opening a pathway through the inner membrane. The energy flowing through this pathway combines with ADP and phosphate (chemiosmosis) to make a net amount of 32 ATPs (University of Illinois, n.d.). The process of chemiosmosis is where the major difference of ATP production can be seen. In glycolysis and the Krebs cycle production of ATP, phosphates are first connected to a metabolic intermediate before being transferred to a ADP molecule. In chemiosmosis, phosphates and ADP (due to ATP synthesis) is already combined and flows as protons down their gradient (Pruitt & Underwood, 2006, para. 4, pg. 296). Why Do Humans Need to Breath Oxygen It is oxygen, connected to hemoglobin of erythrocytes, which carries life sustaining nutrients to our cells. Without oxygen our cells would begin to die. Muscle cells may store some nutrients for energy however, once those nutrients are used and they are not replaced, the cells will begin to die. Another aspect to look at is that nerve cells do not store nutrients and the process of cell death begins unless the nutrients received via oxygen are not restored. Therefore our nervous system is totally dependent on the nutrients oxygen carries via hemoglobin of erythrocytes. This in itself would lead to the question; could the blockage of adequate supply of oxygen to nerve cells be a cause of neurological disorders (Clermont College, n.d.)' References Clermont College. (n.d). Cellular Respiration and Fermentation. Retrieved from http://biology.clc.uc.edu/courses/bio104/cellresp.htm Pruitt, N. L., & Underwood, L. S. (2006). Bioinquiry: Making connections in biology (3rd ed.). Hoboken, NJ: John Wiley & Sons. University of Illinois. (n.d). Glycolysis, Krebs Cycle, and other Energy-Releasing Pathways. Retrieved from http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect12.htm Bibliography: UOP student with a GPA of 3.98. Major is Medical Records Administration and Billing and coding. Have 25 plus years as a nurse with 6 of those years spent as a prior authorization nurse for Medicaid.