Anatomy And Physiology: Cellular Metabolism

Reference Page

Donald, Rizzo C. "Cellular Metabolism." Fundamentals of Anatomy and Physiology. 3rd ed. New York: Delmare, 2010. 64-70. Print.
"The Guide: Glycolysis." ThinkQuest. Oracle Foundation, n.d. Web. 25 June 2012. <http://library.thinkquest.org/27819/ch4_4.shtml>.
"Specialized Cell Structure and Function." : Cellular Respiration — FactMonster.com. 2000–2012 Pearson Education, Publishing as Fact Monster, n.d. Web. 25 June 2012. <http://www.factmonster.com/cig/biology/cellular-respiration.html>.
"Fermentation." McGraw-Hill Higher Education: Anatomy & Physiology Prep. Mcgraw-Hill, 2007. Web. 25 June 2012. <http://www.jlhahnconsulting.com/prepsteps1/bioF6.html>.
Smith, S.E., and O. Wallace. "Why Is Metabolism
The first step in glycolysis occurs in the cytoplasm of the cell. As a result of the breaking down of an ATP molecule into ADP and PO4, energy is released that allows for the phosphate to be added to the glucose. The glucose phosphate quickly changes to another sugar phosphate(C6) called fructose phosphate. ATP is then broken down again into ADP and PO4 to release energy to ass a phosphate to the fructose phosphate, thus creating fructose diphosphate. In order for ATP to be created, two ATP will be used in the first step of the glycolysis process and will need to be paid back out of the end production amount of ATP. Next, the fructose diphosphate splits into two phosphoglyceraldehyde molecules known as PGAL. The two PGALs oxidize because each loses two hydrogen atoms to the electron carrier molecule NAD to form two phosphoglyceric acids(PGA). Lastly, the two PGAs get broken down to two pyruvic acid(C3) molecules due to high energy releasing reactions(Rizzo 65). The energy in the molecule of pyruvic acid is converted to four ATP molecules, but two of which has to be paid back. Overall, anaerobic glycolysis produces two ATP in the breakdown of one molecule of glucose into two pyruvic acid molecules. When oxygen is present, eight ATP are produced because of the loss of two hydrogen atoms from both of the PGALs that were given to the NAD via the electron transport system thus producing two NADH2+
Just like in glycolysis, yeast cells break glucose down to produce two molecules of pyruvic acid, two ATP, and two NADH2+. Seeing how oxygen is not being used, the difference between fermentation and glycolysis is that the pyruvic acid molecules do not go on to the Krebs cycle. Instead the pyruvic acid is broken down into acetaldehyde(CO2 and C2 compound) by the yeast enzyme decarboxylase(Rizzo 70). Unlike the aerobic respiration, NADH2+ does not give its electrons to oxygen, but rather donate its two hydrogen atoms to acetaldehyde by using another yeast enzyme causing the regeneration of NAD and forms ethyl alcohol. The fermentation process as well as the anaerobic production of ATP by the muscles are less efficient in ATP production than the aerobic respiration because only two ATP molecules are produced for every one molecule of glucose compared to eight ATP molecules produced in the aerobic process. Other food compounds are used as energy sources because the substances in food are converted to usable chemical energy known as ATP. The body takes what we ingest and breaks down the substances to rebuild useful substances to promote energy. Carbohydrates(like starch and glycogen) and sugars(like monosaccharides and disaccharides) can be stored in the body as a backup supply to form ATP. Fatty acids are broken down to glycerol to be used in glycolysis. Proteins are broken down to amino acids the body can be used