* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Human Physiology - Maryville University
Survey
Document related concepts
Electron transport chain wikipedia , lookup
Microbial metabolism wikipedia , lookup
Genetic code wikipedia , lookup
Proteolysis wikipedia , lookup
Light-dependent reactions wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Biosynthesis wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Transcript
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 5 Cell Respiration & Metabolism 5-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 5 Outline Glycolysis Aerobic Respiration Fat & Protein Metabolism 5-2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Metabolism Is all reactions in body that involve energy transformations Divided into 2 categories: Catabolism breaks down molecules & releases energy Is primary source of energy for making ATP Anabolism makes larger molecules & requires energy Source of body’s large energy-storage compounds 5-3 Glycolysis 5-4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis Is metabolic pathway by which glucose is converted to 2 pyruvates Does not require oxygen Overall net equation is: glucose + 2NAD + 2ADP + 2Pi 2 pyruvates + 2NADH + 2 ATP 5-5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis continued Glycolysis is exergonic - produces net of 2ATPs & 2NADHs However, glucose must be activated with 2ATPs (phosphorylation) before energy can be obtained Phosphorylation traps glucose inside cell Below can see 2ATPs added & 4 are produced for a net gain of 2 ATP Fig 5.1 5-6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis continued Fig 5.2 5-7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lactic Acid Pathway To avoid end-product inhibition, NADHs produced in glycolysis need to give Hs away In absence of O2, NADH gives its Hs to pyruvate creating lactic acid (anaerobic respiration) Makes muscles feel fatigued Fig 5.3 5-8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lactic Acid Pathway continued RCCs don't have mitochondria; use only lactic acid pathway Occurs in skeletal & heart muscle when oxygen supply falls below critical level During heavy exercise or vascular blockage 5-9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycogenesis & Glycogenolysis For osmotic reasons cells can't store many free glucoses Instead store glucose as glycogen (glycogenesis) Skeletal muscle & liver store lots of glycogen Glycogenolysis clips glucose out of glycogen as glucose 6-phosphate Phosphate groups trap molecules in cells 5-10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycogenesis & Glycogenolysis continued Skeletal muscles use trapped glucose-6phosphate for own energy needs Only liver has glucose-6phosphatase that removes phosphate groups So glucose can be secreted Fig 5.4 5-11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cori Cycle Some skeletal muscle lactic acid goes to liver Where it is converted back through pyruvate to glucose & glycogen Called gluconeogenesis Also can happen with amino acids & glycerol Fig 5.5 5-12 Aerobic Respiration 5-13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aerobic Respiration Begins when pyruvate formed by glycolysis enters mitochondria C02 is clipped off pyruvate forming acetyl CoA (coenzyme A is a carrier for acetic acid) C02 goes to lungs Energy in acetyl CoA is extracted during aerobic respiration in mitochondria Fig 5.6 5-14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Krebs Cycle Fig 5.7 Begins with acetyl CoA combining with oxaloacetic acid to form citric acid In a series of reactions citric acid converted back to oxaloacetic acid to complete the pathway 5-15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Krebs Cycle continued Produces 1 GTP, 3 NADH, & 1 FADH2 NADH & FADH2 carry electrons to Electron Transport Chain (ETC) 5-16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Krebs Cycle continued Fig 5.8 5-17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Electron Transport & Oxidative Phosphorylation The electron transport chain is a linked series of proteins on the cristae of mitochondria Proteins are FMN, coenzyme Q, & cytochromes Fig 3.10 5-18 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Electron Transport & Oxidative Phosphorylation continued NADH & FADH2 from Krebs carry electrons to ETC Which are then shuttled in sequence through ETC NAD & FAD are regenerated to shuttle more electrons from Krebs Cycle to ETC 5-19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Electron Transport & Oxidative Phosphorylation continued As each protein in ETC accepts electrons it is reduced When it gives electrons to next protein it is oxidized This process is exergonic Energy is used to phosphorylate ADP to make ATP Called oxidative phosphorylation Fig 5.9 5-20 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chemiosmotic theory Energy gathered by ETC is used to pump H+s into mitochondria outer chamber Creating high H+ concentration there As H+s diffuse down concentration & charge gradient thru ATP synthase, & back into inner chamber, their energy drives ATP synthesis (Chemiosmotic theory) Fig 5.10 5-21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Function of Oxygen Fig 5.10 Electrons added to beginning of ETC are passed along until reach end Have to be given away or would stop ETC O2 accepts these electrons & combines with 4H+s O2 + 4 e- + 4 H+ 2 H20 5-22 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP Formation ATP can be made 2 ways: Direct (substrate-level) phosphorylation Where ATP is generated when bonds break Both ATPs in glycolysis made this way 2 ATPs/glucose in Kreb's made this way Oxidative phosphorylation in Kreb's Where ATP generated by ETC 30-32 ATPs made this way 5-23 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP Formation continued 3H+s pass thru ATP synthase to generate 1 ATP This yields 36-38 ATPs/glucose However some of these are used to pump ATPs out of mitochondria So net yield is 30-32 ATPs/glucose Really takes 4H+s to generate 1 exported ATP 5-24 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Production of ATP by ETC 2.5 ATP produced for each pair of electrons NADH donates 1.5 ATP produced for each pair of electrons FADH2 donates Net of 26 ATP produced in ETC 5-25 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Net Production of ATP 26 ATP produced in ETC 2 from glycolysis 2 from direct phosphorylation in Kreb’s For total of 30 ATPs for each glucose 5-26 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5-27 Fat & Protein Metabolism 5-28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fats & Proteins as Energy Sources Fats can be hydrolyzed to glycerol & fatty acids These can be modified to run thru Kreb's Proteins can be broken down to amino acids Which can be deaminated & run thru Kreb's These pathways can be used to interconvert carbohydrates, fats, & proteins 5-29 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Energy Storage When more energy is taken in than consumed, ATP synthesis is inhibited Glucose converted into glycogen & fat Fig 5.11 5-30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Acetyl CoA Is a common substrate for energy & synthetic pathways Fig 5.12 5-31 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fat Synthesis (Lipogenesis) Acetyl CoAs can be linked together to form fatty acids Fatty acids + glycerol = Fat (triglycerides) Occurs mainly in adipose & liver tissues Fat is major form of energy storage in body Yields 9 kilocalories/g Carbs & proteins yield only 4/g 5-32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lipolysis Is breakdown of fat into fatty acids & glycerol Via hydrolysis by lipase Acetyl CoAs from free fatty acids serve as major energy source for many tissues 5-33 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Acetyl CoA from Fat --Beta-Oxidation Beta-oxidation clips acetyl CoAs off fatty acid chains Which can be run thru Kreb's giving 10ATPs each Plus oxidation itself yields 4 ATPs Fig 5.13 5-34 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brown Fat Amount of brown fat greatest at time of birth Major site for thermogenesis in the newborn Brown fat produces uncoupling protein, causing H+ to leak out of inner mitochondrial membrane Less ATP produced, causes electron transport system to be more active Heat produced instead of ATP 5-35 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ketone Bodies Triglycerides are continually broken down & resynthesized Ensures blood will contain fatty acids for aerobic respiration During fasting & diabetes lots of fat is broken down Causes high levels of ketone bodies Fat metabolites Gives breath an acetone smell 5-36 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Amino Acid Metabolism Nitrogen (N) ingested primarily as protein Which is used in body as amino acids Excess is excreted mainly as urea 5-37 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nitrogen (N) Balance Nitrogen balance = N ingested minus N excreted Positive N balance: more N ingested than excreted Negative N balance: less N ingested than excreted In healthy adults amount of N excreted = amount ingested Excess amino acids can be converted into carbos & fat 5-38 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Essential & Non-essential Amino Acids 20 amino acids used to build proteins 12 can be produced by body 8 must come from diet (= essential amino acids) 5-39 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Transamination New amino acids can be obtained by transamination Which is addition of -NH2 to pyruvate or Kreb's cycle ketones to make a new amino acid Catalyzed by transaminase 5-40 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig 5.14 Transamination continued 5-41 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Oxidative Deamination Is process by which excess amino acids are eliminated -NH2 is removed from glutamic acid, forming keto acid & ammonia Ammonia is converted to urea & excreted Keto acid goes to Kreb’s or to fat or glucose Fig 5.15 5-42 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Gluconeogenesis Occurs when amino acids are converted to Keto acids, then pyruvate, then glucose 5-43 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Uses of Different Energy Sources Different cells have different preferred energy substrates Brain uses glucose as its major source of energy 5-44