Hun1201 Study Guide Test 3 Ch 7 9 14 Ch 7 Why is Metabolism Essential For Life Metabolism sum of all chemical and physical changes that occur in body tissues Calorimeter instrument in which food can be burned and the amount of heat that is released can be measured measures energy content of food The process of making larger chemically complex molecules from smaller more basic ones is called anabolism Process is critical for growth repairing and maintaining the body s tissues and synthesizing the chemical products essential for human functioning Energy that fuels anabolic reactions is chemical energy Catabolism breakdown or degradation or larger more complex molecules to smaller basic molecules releases chemical energy Begins with digestion macro nutrients are broken down into amino acids fatty acids glycerol and monosaccharide s and transported to body cells and when cells need energy they can catabolize into smaller molecules Used to break down old cells or tissues that need to be repaired or replaced Energy to fuel anabolic reactions comes from body s catabolic reactions Body balances the two reactions exceptions occur when there is an excess anabolic state during childhood growth When cells catabolize nutrients such as glucose they package the energy that is released during the reaction in a compound called adenosine triphosphate ATP When these bonds are broken their energy is released and can be used to perform the work of the cell Energy is used to build new molecules break down old molecules and keep the cell functioning optimally Adenosine diphosphate ADP a metabolic intermediate that results from the removal of one phosphate group Adenosine monophosphate AMP low energy compound resulting from removal of two phosphate groups Metabolic pathways are clusters of chemical reactions that occur sequentially and achieve a particular goal Condensation is an anabolic process where smaller compounds are joined by the removal of water A OH H B A B H2O Hydrolysis is a catabolic process where large molecules are broken apart by the addition of water A B H2O A OH H B Phosphoralation is the addition of one or more phosphate groups to a chemical compound Example of when glucose enters a cell o C6H12O6 A P P P C6H12O6 P A P P Oxidation reduction reactions are reactions in which electrons are lost by one compound oxidation and simultaneously gained by another compound reduction Enzymes are essential for the metabolism of the energy containing macronutrient In order to function they require substances called coenzyme and cofactor o Coenzymes are the smaller non protein part of an enzyme FAD FADH2 and vitamins are coenzymes o Cofactors are typically minerals such as iron magnesium or zinc that are required for enzyme activity The enzyme that activates the metabolic reaction in the phosphorylation of glucose is called glucokinase The glucose absorbed from carbohydrates has one of many fates Glucose can be phosphorylated and stored in liver and glycogen or Glucose can be released and used up by other cells as fuel or stored Or if energy needs are met then they can converted to fatty acids used for energy in muscle tissue as glycogen and stored as adipose tissue Energy extracted from Carbohydrates Glycolysis is a sequence of chemical reactions that converts glucose to pyruvate occurs in the cytosol anaerobic requires 2 ATPs but produces 4 ATPs 2 net ATPs to be used as energy 2 Hs that are released are picked up by the coenzyme NAD thus forming NADH Pyruvate molecules can be used up as energy after undergoing metabolic steps or can be resynthesized to glucose through gluconeogenesis In the absence of oxygen the pyruvate produced in gylcolysis can be anaerobically converted to lactate or lactic acid Occurs in a one step reaction where H is acquired Lactate is produced from the NADH H yielded during gylcolysis so the production of lactate therefore regenerates the NAD required for the continued function of the gylcolysis pathway Occurs in cells with few or no mitochondria and in muscles during high intensity exercise when oxygen delivery to the muscles is limited In the presence of oxygen pyruvate is converted to a two carbon compound known as Acetyl CoA and occurs in the mitochondria Reactions takes in NAD and produces NADH H Acetyl CoA is a two carbon compound where the third C from pyruvate end up with the gas CO2 which the lung exhales Acetyl CoA cant be resynthesized to glucose like lactate can but can be metabolized to produce ATP or redirected into fatty acid synthesis when ATP is abundant The tricarboxylic acid TCA cycle creb cycle is a repetitive series of 8 metabolic reactions located in cell mitochondria that metabolizes acetyl CoA for the production of carbon dioxide high energy GTP and reduced coenzymes NADH and FADH2 Oxaloacetate and other metabolic intermediates are necessary for continued functioning of the TCA cycle Oxaloacetate is mostly derived from dietary carbohydrates Every glucose after gylcolysis produces 2 pyruvate s leading to two acetyl CoA s So 1 glucose molecule 2 TCA cycles Final stage in glucose oxidation is called oxidative phosphorylation Occurs in the electron transport chain a series of metabolic reactions that transports electrons from NADH or FADH2 through a series of carriers resulting in ATP production The complete process of glucose oxidation starts with glucose and ends with the production of carbon dioxide water and ATP Energy extracted from Fats Lipolysis is the enzyme driven catabolism of triglycerides into free fatty acids 3 and glycerol Triglycerides are broken down though the enzyme lipoprotein lipase in lipoproteins and by hormone sensitive lipase in adipose cells The glycerol part of the triglyceride doesn t produce much energy but can be converted to pyruvate or used for regeneration of glucose The fatty acids are attached to albumin a blood protein and transported to cells that need energy They are catabolized for energy through the process oxidation fatty acid oxidation o The fatty acid must first be activated by Coenzyme A before its shuttled across the mitochondrial membrane by carnitine o More acetyl CoA and more ATP are produced during oxidation than during glucose catabolism o Fatty acids have a higher energy potential 9 kcal g compared to carbohydrates 4 kcal g o There is no metabolic pathway that converts fatty acids to glucose If there is a low intake of carbohydrates then the TCA cycle will slow its production because it needs
View Full Document
Unlocking...