KIN 292 1st Edition Lecture 7 These come from the slideshows provided by the professor and include extra notes and explanations Highlighted or bolded information are things that I believe to be information that is important to look over multiple times The notes in red are my personal additions and quotes of Professor Starnes from the class lecture Outline of Last Lecture I 3 3 Reaction Rates II 3 4 ATP The Medium of Energy Exchange continued from Friday III 3 5 Glucose Oxidation The Central Reaction of Energy MetabolismFour basic types Outline of Current Lecture I 3 6 Stages of Glucose Oxidation Glycolysis finish last lecture the Krebs Cycle and Oxidative Phosphorylation II 3 7 Energy Storage and Use Metabolism of Carbohydrates Fats and Proteins Current Lecture Stages of Glycolysis 6 carbon F1 6BP slit in half to two 3 carbon molecules very big increase in entropy randomness Note the two molecules are different when first split but both become glyceraldehyde 3 phosphate almost immediately Pi is attached to 3 carbon NAD coenzyme needed to take H removed form C1 so Pi can bind to the available C Both Pi groups are subsequently put on ADP to form ATP via substrate level phosphorylation further down the line NADH must be These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute recycled back to NAD or else glycolysis will slow down Law of mass action Knowing how NAD is re supplied is very important Summary of Glycolysis NADH To mitochondria or to lactate Your author says O2 availability decides the fate However lactate is produced even when oxygen is present Let s see why Also will either go into mitochondria or to lactate reaction glucose 2 NAD 2 ADP 2 Pi 2 pyruvate 2 NADH 2 H 2 ATP Two ways to regenerate NAD from NADH so that Gly 3 P DH is not slowed Option 1 Mitochondria NADH shuttles move H from cytosol to mitochondria and thereby re supply cytosolic NAD to Gly 3 P DH Mitochondrial membrane impermeable to NAD NADH Cytosol requires high NAD NADH mitochondria needs high NADH NAD This option regenerates cytosolic NAD and contributes to mitochondrial ATP synthesis cytosol high NAD low NADH Mitochondria high NADH low NAD Option 2 LDH reaction Occurs when O2 concentration is too low for mitochondria to work author or When rate of glycolysis exceeds capacity of mitochondria shuttles to re supply NAD even when high O2 is present In this case elevated NADH pushes LDH reaction toward NAD lactate Mass action Author does not seem to appreciate the latter point No ATP production from NADH but glycolysis can continue at a very fast rate Won t get NAD from the ATP directly UNDERSTANDING EXERCISE clarifications regarding anaerobic glycolysis Weight lifter Author says muscle cells depend on anaerobic glycolysis because they need a lot energy quickly and blood flow to tissue is not fast enough to provide the needed O2 for oxidative phosphorylation Cells do need to use glycolysis as a major energy source because it can synthesize ATP faster than the aerobic phase of glucose oxidation or fatty acid catabolism Glycolysis is always anaerobic whether O2 is present or not Even when O2 availability is high the lifter would be using glycolysis as the dominant pathway for ATP synthesis and there would be lots of lactic acid produced because the high glycolytic rate would be producing more NADH than the mitochondria shuttles can handle Distance runner Author says will not be using maximum exertion during most of a 2 mile run therefore the runner does not require anaerobic glycolysis for energy as the weight lifter does There is plenty of O2 available to her muscles and she may not be utilizing ATP as fast as the lifter but she is still using anaerobic glycolysis because it is always the first phase of glucose oxidation Author says In a race runner would sprint at the end and use lots of anaerobic glycolysis Even in this case there is plenty of O2 getting to her muscles She needs to increase the rate of glycolysis to increase her rate of ATP synthesis and there will be lots of lactic acid produced to supplement the saturated mitochondria NADH shuttles Efficiency of glycolysis Glucose to Lactate Glucose 686 kcal 2 Lactates 317 kcal each 634 686 634 52 kcal expended 2 ATPs produced 7 x 2 14 kcal 14 52 27 Why is this different from your book Glycolysis Glucose A to 2 Lactates B 52 C to D 14 for 2 ATPs 27 efficient Efficiency of glycolysis Glucose to Lactate 14 52 27 Why is this different from your book She does not consider the potential energy still remaining in lactate she uses the energy released when glucose is catabolized to completion 6CO2 and 6H2O where 38 ATP are synthesized Your book 14 686 2 Where does the energy in lactate go What happens to the lactate produced in a muscle Lactate Shuttle 1 Lactate released by a muscle is catabolized to CO2 and H2O in another organ It s converted to pyruvate enters mitochondria later the highest ATP demand What happens to the lactate produced in a muscle Lactate Shuttle 2 Released lactate may also be used for synthesis of glucose glycogen in liver Liver organ that has so it will have more lactic acid The organs taking up lactate have high mitochondria content which means they have a lots of NADH shuttles Therefore the NADH produced when lactate is converted to pyruvate goes into mitochondria and does not alter cytosolic NAD NADH ratio Pyruvate enters mitochondrion PDH complex Links glycolysis to Krebs cycle compare with Fig 3 16