Week 7 Notes
Week 7 Notes FSCN 1112
U of M
Popular in Principles of Nutrition
Popular in Nutrition and Food Sciences
This 4 page Class Notes was uploaded by Alexandra Cummins on Sunday October 25, 2015. The Class Notes belongs to FSCN 1112 at University of Minnesota taught by Mashek, Douglas in Summer 2015. Since its upload, it has received 16 views. For similar materials see Principles of Nutrition in Nutrition and Food Sciences at University of Minnesota.
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Date Created: 10/25/15
Week 7 Metabolism How do we get energy from food 0 O O Food02gt C02H20energy as ATP and heat Gross energy the total potential energy of the food if you were to light it on fire this is how much energy would be released as light and heat Digestible energy energy the body can absorb through digestion this is the gross energy minus the fiber we eat because we can t digest fiber this is about 5 less than the gross energy Metabolized energy all of the energy that makes it to the cells about 5 of the energy is digestible but not metabolized An example of this might be urea in the blood Net Energy the actual energy the body can use stored as ATP I 60 of the gross energy is lost through heat Important definitions 0 O Metabolism coordinated network of reactions in the body that keep an organism alive Metabolic pathway set of reactions that occur from beginning to end to preform a specific function Intermediates Metabolites compounds formed in the middle of a pathway Anabolic pathways that build compounds carbs proteins needs energy Catabolic pathways that break down compounds give off energy I Anabolic and catabolic reactions are closely linked ATP adenosine triphosphate the body s basic source of energy when ATP is broken down it gives off energy The body gets energy from proteins carbs lipids and alcohol Those are digested and then absorbed Amino acids monosaccharides and fatty acids are all converted into acetyl CoA before they are used to make energy AcetylCoA goes into the citric acid cycle to make end products Review of oxidation and reduction reactions 0 O O O O Electrons are transferred Oxidized looses electrons gains 0 atoms or looses H atoms Reduced gains electrons loosed O atoms or gains H atoms Coenzymes help carry electrons ex NADH comes from niacin Ex Glucose is oxidized to release energy C02 and H20 are reduced ATP production from carbs O O 0 Cellular respiration oxidizes removes electrons to get ATP Aerobic respiration need oxygen yields 3032 ATP per glucose in the mitochondria Anaerobic respiration doesn t need oxygen yields 2 ATP per glucose Used by cells without mitochondria red blood cells and in muscle cells during extreme exertion Steps of ATP production 0 Glycolysis 1 glucose is made into 2 pyruvate molecules need glucose 2NAD 2ADP and 2 Pi produces 2 pyruvate 2ATP H20 and 2 NADH happens in cytosol o The transition reaction 1 pyruvate makes 1 acetylCoA molecule multiply everything by 2 for one glucose molecule makes NADH and C02 pyruvate looses a carbon acetylCoA is produced 0 Citric acid cycle multiply everything by 2 for one glucose molecule Need acetylCoA 3NAD FAD GDP then converted to ATP Produced C02 1 ATP as GTP 3 NADH and FADH2 0 Electron transport chain Uses the electrons that the carriers have NADH Also called oxidative phosphorylation Minerals are very important for processing iron and copper NADH and FADH2 donate electrons and protons H H is pumped in between membranes in mitochondria to build a gradient H is then released back and when it crosses membrane it makes ATP Oxygen is needed to take away electrons so the process can con nue Brown fat studies have found that H ions are leaked in brown fat cells when the body needs more heat Anaerobic metabolism 0 0ccurs in cells without mitochondria o Pyruvate is converted into lactic acid instead of acetylCoA ATP production from fat 0 Lipolysis triglycerides are broken down into fatty acids and glycerol 0 Fatty acid go into the blood and then into the cells 0 Fatty acids are then oxidized Takes place in the mitochondria Carnitine gets the fatty acids into the mitochondria Yields acetylCoA 0 Beta oxidation Process chops off 2 carbons at a time A lot of acetylCoA is produced a 16 carbon fatty acid makes 8 acetylCoA The process also produces NADH and FADH2 0 Complete oxidation of a fatty acid yields about 106 ATP fat is very energy dense Carbs aid fat digestion 0 Broken down glucose can be made into other intermediates of the citric acid cycle speeding up the process 0 Ketogenesis when acetylCoA builds up because there are not enough carbs in the citric acid cycle it turns into ketone bodies this happens in the liver I Ketones are acids in the blood and can cause ketoacidosis Steps to ketogenesis Insulin levels are low The body decides to burn fat Fatty acids are broken down into acetylCoA If there are not enough sugars present acetylCoA becomes ketones Protein metabolism 0 Deamination the amino acid looses the amine group which is processed in the liver and excreted as urea 0 After the amine group is gone the remaining molecule is just a carbon backbone that can be used for energy I Ketogenic amino acids goes to acetylCoA to be burned I Glucogenic amino acids the backbone can be turned into pyruvate which can be burned like glucose I Glucogenesis the process where amino acids are form glucose Other molecules that can become glucose glycerol and lactate Fatty acids can t be converted straight to glucose Most processes take place in the mitochondria it is the major site of energy production in a cell except for glycolysis which takes place in the cytosol Synthesis of fatty acids 0 Most are made from extra sugars o Happens mostly in the liver 0 AcetylCoA is taken in the liver to build chains 2 carbons at a time up to 16 carbons o This process is driven by glucose and insulin levels Alcohol metabolism 0 You get acetylCoA and lots of NADH 0 Fatty liver develops when too much acetylCoA builds up in the liver and has to get converted to fat Regulation of Energy Metabolism 0 System is very complex body wants to maintain homeostasis a level of constant supply 0 ATP concentration energy concentrations regulate the rate of production 9WNH39 o The concentrations of nutrients and metabolites play a big role in in regulating systems Fasting 0 First glycogen is broken down 0 Then fat will be burned 0 Protein will be burned once there is no more fat 0 Glucogenesis increases as time goes on Feasting o Glycogen is stored then fat is stored protein is stored and urea is synthesized 0 Fatty acids and alcohol can t be converted to glucose but just about everything can be made into fat for storage Inborn errors of metabolism 0 Mutations occur that change specific pathways making those products and the foods they come from impossible to use 0 PKO phenylketonuria the body can t digest phenylalanine so it builds up in the brain and can cause damage 0 Galactosemia the body is unable to metabolize galactose found in milk 0 Glycogen storage disease the body can t make glucose from glycogen so blood sugar must be closely monitored to prevent hypoglycemia