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Glycolysis and Krebs cycle The biochemistry of aerobic respiration only in sufficient detail to show that: • glycolysis involves the oxidation of glucose to pyruvate with a net gain of ATP and reduced NAD; • pyruvate combines with coenzyme A to produce acetylcoenzyme A; • acetylcoenzyme A is effectively a two-carbon molecule which combines with a four-carbon molecule to produce a six-carbon molecule which enters Krebs cycle; • Krebs cycle involves a series of oxidation reactions and the release of carbon dioxide leading to the production of ATP and reduced coenzyme (NAD or FAD); • synthesis of ATP is associated with the electron transport chain. Mitochondria The structure and role of mitochondria in respiration. Aerobic Respiration Define the following: • • • • Respiration Breathing Aerobic respiration Anaerobic respiration Aerobic Respiration Respiration is the process that releases energy in organic molecules such as sugars and lipids. Respiration takes place in all cells all of the time Breathing is the mechanical process that supplies oxygen to the body for respiration and that removes carbon dioxide produced. Breathing ventilates the gas exchange surfaces. Aerobic Respiration is respiration with oxygen – most organisms respire aerobically releasing a relatively large amount of energy. Anaerobic respiration is respiration without oxygen – some organisms mainly bacteria can only respire anaerobically others can switch to anaerobic when oxygen levels are low. Aerobic Respiration Aerobic respiration describes the cell processes that require oxygen to release energy from all organic molecules. Respiration involves the breakdown of many molecules from the food we eat. Humans respire mainly sugars but also some amino acids and fatty acids. Aerobic Respiration • For any chemical reaction to occur energy is required to break bonds. • The process of forming new bond can either release energy of require eenergy • For there to be a release of energy the products of respiration must be at a lower energy level than the reactants. Aerobic Respiration • What is the basic equation for respiration? • C6H12O6 + 6O2 6CO2 + 6H20 + ENERGY • In reality cell respiration takes place in a series of stages , these can produce a up to 36 molecules of ATP per molecule of glucose • The steps involved in respiration rely on a series of redox reactions Aerobic Respiration Energy in molecules Combustion has one step and occurs very rapidly Glucose and oxygen CO2 +H2O Time Glucose and oxygen Energy in molecules CO2 +H2O Time Energy is lost as heat Respiration occurs in small steps and releases energy in controlled amounts. Less energy is lost as heat Aerobic Respiration NH 2 N N OOO O - P - O - P - O - P - O - CH2 OO O N O adenosine AMP ADP ATP N Aerobic Respiration ATP + H2O AMP + H2O ADP + H2O 30.5 kJ mol Pi -1 30.5 kJ mol Pi -1 adenosine 14.2 kJ mol Pi -1 Aerobic Respiration The process of aerobic respiration can be divided into 4 distinct processes: • • • • Glycolysis Pyruvate Oxidation The Krebs cycle The electron transport chain Aerobic Respiration Stage Site Within Cell Overall process Number of ATP molecules produced Glycolysis Cytosol Glucose is split into 2 molecules of pyruvate 2 per glucose molecule Pyruvate Oxidation Matrix – inner fluid of mitochondria Pyruvate is converted to acetyl co A none Krebs Cycle Electron Transport Chain Aceytyl co A drives a cycle 2 per turn of reactions to produce so 4 per hydrogen glucose Inner memebrane Hydrogen drives a series of mitochondria of redox reactions to produce ATP Up to 32 per glucose