Learning Objectives Define aerobic respiration. Give the overall chemical reaction for aerobic respiration. Name the four stages of aerobic respiration. Summary Aerobic respiration is the aerobic catabolism of nutrients to carbon dioxide, water, and energy, and involves an electron transport system in which molecular oxygen is the final electron acceptor.
In this way, protons behave little differently than, say, water that "wants" to move from an area of higher elevation to an area of lower concentration — here, under the influence of gravity instead of the so-called chemiosmotic gradient observed in the electron transport chain. Like a turbine at a hydroelectric plant harnessing the energy of flowing water to do work elsewhere in that case, generate electricity , some of the energy established by the proton gradient across the membrane is captured to attach free phosphate groups P to ADP molecules to generate ATP, a process called phosphorylation and in this instance, oxidative phosphorylation.
In fact, this happens over and over in the electron transport chain, until all of the NADH and FADH 2 from glycolysis and the Krebs cycle — about 10 of the former and two of the latter — is utilized. This results in the creation of about 34 molecules of ATP per glucose molecule. There are three different points in the electron transport chain at which protons can cross the inner mitochondrial membrane to enter the space between this later and the outer mitochondrial membrane, and four distinct molecular complexes numbered I, II, III and IV that form the physical anchor points of the chain.
The electron transport chain requires oxygen because O 2 serves as the final electron-pair acceptor in the chain. If no oxygen is present, the reactions in the chain quickly cease because the "downstream" flow of electrons ceases; they have nowhere to go.
Among the substances that can paralyze the electron transport chain is cyanide CN -. This is why you may have seen cyanide used as a deadly poison in homicide shows or spy movies; when it is administered in sufficient doses, aerobic respiration within the recipient stops, and with it, life itself. It is often assumed that plants undergo photosynthesis to create oxygen from carbon dioxide, while animals use respiration to generate carbon dioxide from oxygen, thereby helping preserve a neat ecosystem-wide, complementary balance.
While this is true on the surface, it is misleading, because plants make use of both photosynthesis and aerobic respiration. Because plants cannot eat, they must make, rather than ingest, their food.
This is what photosynthesis, a series of reactions that takes place in organelles animals lack called chloroplasts, is for. Powered by sunlight, CO 2 inside the plant cell is assembled into glucose inside chloroplasts in a series of steps that resemble the electron transport chain in mitochondria. The glucose is then released from the chloroplast; most if it becomes a structural portion of the plant, but some undergoes glycolysis and then proceeds through the rest of aerobic respiration after entering the plant cell mitochondria.
Kevin Beck holds a bachelor's degree in physics with minors in math and chemistry from the University of Vermont. Formerly with ScienceBlogs. More about Kevin and links to his professional work can be found at www. The complete chemical reaction describing aerobic respiration is:. The Krebs Cycle Made Easy. What Does Glycolysis Yield? How Does Glycolysis Occur? Enzyme Activity in Photosynthesis. Aerobic and anaerobic respiration Aerobic respiration Respiration using oxygen to break down food molecules is called aerobic respiration.
Anaerobic respiration Most organisms cannot respire without oxygen but some organisms and tissues can continue to respire if the oxygen runs out. This table compares aerobic and anaerobic respiration: Aerobic respiration Anaerobic respiration Oxygen Present Absent or in short supply.
Oxidation of glucose Complete Incomplete. All of the energy available from glucose is not released. Reactants of respiration Glucose and oxygen Glucose. Yeast - ethanol and carbon dioxide and ATP. Some plants - ethanol and carbon dioxide and ATP. Absent or in short supply. Glucose and oxygen. Carbon dioxide and water and ATP. Mammalian muscle - lactic acid and ATP.
0コメント