CHAPTER 9 ENERGY METABOLISM Metabolism Metabolism is the sum of all chemical and physical processes by which the body breaks down and builds up molecules Chemical reactions require or release energy Chemical Reactions in the Body o Metabolic Pathway group of biochemical reactions that occur in a progression from beginning to end o Intermediates compounds formed in one of the many steps in a metabolic pathway o Anabolic Pathway build compounds requires energy o Catabolic Pathway breakdown compounds release energy Energy for the Cell o Adenosine Triphosphate ATP Body s main source of NRG Utilized directly by the cells Hydrolysis of the high energy phosphate bonds releases energy creating ADP free P o Adenosine Diphosphate ADP Recycled back into ATP with the addition of a free P o Adenosine Monophosphate AMP Hydrolysis of ADP Oxidation Reduction Reactions ATP synthesis depends on the transfer of electrons in a series of reactions from NRG yielding compounds to oxygen Reactions occur together Oxidized substance Reduced substance loses electron s gains oxygen loses hydrogen gains election s loses oxygen gains hydrogen enzymes control oxidation reduction reactions Vitamins act as coenzymes The reduction of O to form water is vital to synthesis of ATP Oxidation vs Reduction LEO the lion goes GER OIL RIG Oxidation is loss of electrons Reduction is gain of electrons Penis Gaining and oxygen oxidation Losing an oxygen reduction Metabolic Pathways Metabolic pathways are chemical reactions that occur sequentially to achieve a particular goal Occur in specific types of the cell May be limited to specific organs or tissues energy production in the cell is the site of Cellular Respiration The of obtaining energy in order to produce molecules Oxidation of food molecules to form is the final electron acceptor Aerobic With Anaerobic With Aerobic Cellular Respiration of Glucose 4 Staged Figure 9 5 1 Glycolysis 1 glucose is oxidized to 2 producing NADH H Occurs in the Net ATP 2 Transition reaction CHAPTER 9 ENERGY METABOLISM is oxidized and joined with producing and NADH H an releasing CO2 as waste Occurs in 3 Citric acid cycle CAC enters producing NADH H FADH2 D ATP GTP intermediate and CO2 Occurs in Net ATP from GTP 4 Electron transport chain ETC NADH H FADH2 oxidized to NAD and FAD Occurs in At the end of ETC is combined with H ions to form Net ATP from NADH FADH and GTP Most formed in ETC Mitochondria is the powerhouse of cell Anaerobic Metabolism Anaerobic Glycolysis Occurs in cells with and in cells when there is limited is converted to is picked up by the liver Liver synthesizes compounds used in aerobic metabolism Pyruvate glucose or other aerobic intermediates Not as efficient as aerobic metabolism Net ATP Glycolysis Pathway ATP Production from Fats Lipolysis Breakdown of triglycerides and Free fatty acids are used for or is converted to pyruvate then to Acetyl CoA for entry into the CAC Regulated by hormone sensitive lipase Carnitine shuttles fatty acids from into Fatty acid oxidation Further breakdown of for energy production Fatty Acid Oxidation Beta Oxidation Occurs in Cleaving of carbons at a time Converts into 16 C FA yields net ATP vs 6 C glucose yields net ATP Yields NADH H and FADH2 CHO Aids Fat Metabolism needed to run CAC 1 step in CAC Other intermediates produced via CAC enter different biosynthetic pathways This slows CAC which eventually leads to insufficient can be converted to So as FA create the cells increase the to supply enough Alternate Fat Metabolism Ketogenesis Ketone bodies formed by an fatty acid oxidation Occurs mainly with hormonal imbalances CHAPTER 9 ENERGY METABOLISM E g inadequate insulin to balance glucagon Build up of Contain Cs that become glucose Any part of carbon skeleton that bodies ketosis Some converted to Some are excreted Ketosis In Type 1 Diabetes In semistarvation or fasting Energy from Protein The body prefers using carbohydrates and fats for energy Protein is reserved for metabolic functions that cannot be performed by others Building and repairing body tissues Protein is used for fuel during total energy or low intake Protein Metabolism Primarily in the Muscles metabolize only leucine isoleucine and valine Deamination Loss of the amine group from AA Left with a carbon skeleton Requires vitamin B 6 Carbon skeleton is utilized Enter CAC as Others form or Protein Metabolism Paths for the Carbon Skeleton Amino Acids Contain Cs that become glucose form pyruvate Any part of carbon skeleton that can Or bypass Acetyl CoA synthesis and enter CAC directly Amino Acids becomes Acetyl CoA Key between the two Can part or all of carbon skeleton of AA yield a new oxaloacetate during metabolism Because 2 are needed to form glucose Gluconeogenesis A metabolic pathway that results in the generation of from carbon substrates such as pyruvate lactate glycerol glucogenic amino acids and odd chain fatty acids Only in and certain kidney cells Begins in mitochondria returns to cytosol Requires B vitamins and ATP Typical fatty acids cannot be converted to glucose although glycerol can Protein Metabolism What happens to the amine group Disposal of Excess Amino Groups Catabolism of AA yields amine groups NH2 in the Converted to NH3 Excreted by in the urine with urea cycle Nitrogen in blood is used as Dx tool Ammonia build up in blood disease Urea build up in the blood disease Regulation of Energy Metabolism Liver Major role Location of nutrient interconversions and storage ATP Concentrations CHAPTER 9 ENERGY METABOLISM High ATP promotes rxns High ADP stimulated rxns Enzymes Hormones Vitamins and Minerals metabolic pathways Vitamins and Minerals in Cell Metabolism Overview of Macronutrient Metabolism Fasting and Feasting Fasting encourages breakdown breakdown Synthesis of bodies Feasting encourages Glycogen Fat and Protein Urea Metabolism of ATP Yielding Compounds Table 9 2 Stored Energy Stored energy can be used during times of Extra energy is stored as Glycogen Carbohydrate in limited amounts in and Triglycerides Fat in unlimited amounts in tissue limited in liver and muscle Body has no mechanism for storing or Synthesizing Macronutrients Gluconeogenesis Making glucose from non glucose substrates Primarily from Small amount from Maintains levels during sleep fasting illness and exercise Protein catabolism For production can draw on tissue proteins skeletal heart and organ proteins Lipogenesis Making fat from substrates such as Occurs when consuming calories beyond