metabolism - Cellular Metabolism s Energy as it relates to...

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Unformatted text preview: Cellular Metabolism s Energy as it relates to Biology Metabolism s s Catabolism (ATP production) s Glycolysis and the TCA Cycle Protein Synthesis s Anabolism (Synthetic pathways) s Metabolism Metabolism s Definition = “All chemical reactions that take Definition place within an organism.” place Metabolic pathways = network of linked reactions Basic feature: coupling of exergonic rxs with endergonic rxs. (direct vs. indirect coupling) (direct s s Review: Review: s Energy = capacity to do work s Usually from ATP s Enzymes = biological catalyst s Lower activation energy s Return to original state s Opportunity for control Metabolism Catabolism → Energy Anabolism → Synthesis Energy transferred commonly measured in calories: 1 cal = ↑ 1 g of H2O by 1° C 1 Kcal = ↑ temp. of 1L H2O by 1o C. = Calorie (capital C) Energy released in catabolic reactions is trapped in Energy 1) Phosphate bonds 1) 2) Electrons Metabolic pathways: Network of interconnected chemical reactions interconnected Linear pathway Intermediates Circular pathway Branched pathway Control of Metabolic Pathways Control (Chapter 6) 1. 1. Enzyme concentration (already Enzyme covered) covered) Enzyme modulators Enzyme - Feedback- or end product inhibition inhibition - Hormones - Other signaling molecules 1. Different enzymes for Different reversible reactions reversible Enzyme isolation Energy availability (ratio of Energy ADP to ATP) ADP 1. 2. Catabolic Pathways: ATP-Regeneration ATP Amount of ATP produced reflects on usefulness of metabolic pathways: Aerobic pathways Anaerobic pathways Different biomolecules enter pathway at different points ATP = Energy Carrier of Cell (not very useful ATP for energy storage) ATP Cycle ATP : ADP ratio determines status of ATP synthesis reactions Glycolysis Glycolysis s From 1 glucose (6 carbons) to 2 From pyruvate (3 carbons) molecules pyruvate Main catabolic pathway of cytoplasm Does not require O2 ⇒ common for (an)aerobic catabolism (an)aerobic Starts with phosphorylation of Starts Glucose to Glucose 6-P Glucose s s s s (“Before doubling your money you first (“Before have to invest!”) have The Steps of The Glycolysis Glycolysis Net gain? Pyruvate has 2 Possible Fates: Anaerobic catabolism: Pyruvate Lactate Aerobic catabolism: Pyruvate Citric Acid Cycle Intermediate Step Intermediate Glycolysis Glycolysis Citric Acid Cycle Citric Other names ? Takes place in ? Energy Produced: 1 ATP 3 NADH NADH 1 FADH FADH Electron transport System Energy Yield of Krebs Cycle NADH NADH NADH FADH2 Final step: Electron Transport Final s s System Chemiosmotic theory / oxidative phosphorylation Transfers energy from NADH and FADH2 to ATP (via e- donation and H+ transport) (via donation s Mechanism: Energy released by movement of e- through transport system movement is stored temporarily in H+ gradient is NADH produces a maximum of 2.5 ATP NADH FADH2 produces a maximum of 1.5 ATP FADH 1 ATP formed per 3H+ shuttled through ATP Synthase s s Organelles Organelles Electron Transport Chain Electron s On the inner membrane of the On mitochondria mitochondria s Protein complexes including enzymes and Protein iron-containing proteins called cytochromes cytochromes Movement of electrons through the etc to Movement produce ATP produce s Chemiosmotic Theory s Steps to produce ATP Steps s s s s Pairs of high-energy electrons pass from complex to Pairs complex along the etc. complex Energy released by these reactions is used to pump Energy H+ from the mitochondrial matrix into the intermembrane space. intermembrane The movement of protons creates a concentration The gradient gradient As the protons move down their concentration As gradient into the matrix potential energy stored in the concentration gradient is transferred to the high – concentration energy bond of ATP Oxidative Phosphorylation Oxidative s Oxygen is required as the final electron Oxygen and proton acceptor and ATPsynthase ATPsynthase s s s When the protons move back into the When mitochondrial matrix through a pore in ATPsynthase stored energy is converted into chemical-bond energy chemical-bond The ATPsynthase transfers KE to the highenergy phosphate bond of ATP energy A portion of this energy transfer is released portion as heat and absorbed into the blood as Electron Transport Chain Electron Summary of CHO catabolism Cellular Respiration Respiration Maximum potential yield for aerobic glucose metabolism: 30-32 ATP synthesized from ADP H2O is a byproduct Glycogen Synthesis Glycogen Made from glucose Stored in all cells but especially in s Liver (keeps 4h glycogen reserve for between meals) Liver (keeps s Skeletal Muscle → muscle contraction Skeletal Gluconeogenesis Glycolysis in reverse From glycerol, aa and lactate All cells can make G-6-P, only liver and Kidney can make glucose Water Soluble Vitamins Water s B1 (Thiamine) s Part of coenzyme cocarboxylase s Transformation of pyruvic acid to acetyl CoA Beriberi s s s s s s s Deficits s Decreased appetite Vision disturbances Unsteady gait Loss of memory and confusion Fatigue tachycardia Water Soluble Vitamins Water s B2 (Riboflavin) s FAD and FMN s Hydrogen acceptors in body s Deficits Cracking of lips Cracking s Tongue turns purple red and shiny s Light sensitivity s Decreased energy s Water Soluble Vitamins Water s B3 (Niacin) s s Constituent of NAD Deficits s s s s s s s s s Listlessness Headache Weight loss and loss of appetite Sore red tongue and lips Nausea Nausea Vomiting Diarrhea Photosensitivity Cracked and ulcerated skin Water Soluble Vitamins Water s B6 (Pyridoxine) s Coenzyme pyridoxal phosphate Functions in amino acid metabolism s Formation of antibodies and hemoglobin s s Deficits Increased risk of heart disease s Seborrhea around eyes and mouth s In infants: nervous irritability and convulsions s Water Soluble Vitamins Water s B5 (Pantothenic acid) s Coenzyme A s Deficits Loss of appetite s Abdominal pain s Depression s Muscle spasms s Water Soluble Vitamins Water s Biotin s s Coenzyme for Krebs cycle Deficits s s s s s s s Scaly skin Muscle pain Pallor Anorexia Nausea Fatigue Elevated blood cholesterol Water Soluble Vitamins Water s C (Ascorbic Acid) s Antioxidant s Formation of connective tissue s Converts tryptophan to serotonin s Enhances iron absorption s Deficits Joint pains and poor both and tooth growth s Poor wound healing s scurvy s Water Soluble Vitamins Water s B12 (Cyanocobalamin) s s s s Coenzyme in gastrointestinal cells, nervous tissue Coenzyme and bone marrow and Synthesis of DNA Division of erythrocytes Deficit s Pernicious Anemia s s s s Pallor Anorexia Dyspnea Weight loss Water Soluble Vitamins Water s Folic Acid s s s s s Coenzymes for synthesis of methionine and other Coenzymes amino acids amino DNA synthesis Formation of red blood cells Formation of normal neural tube in embryonic Formation development development Deficits s s s s s s s Megaloblastic anemia Gastrointestinal disturbances Diarrhea Spina bifida in new born Low birth weight Neurological deficits Increased risk of heart attack and stroke Fat Soluble Vitamins Fat s A (Retinol) s Synthesis of photoreceptor pigments s Development of teeth and bone s Antioxidant s Deficits Night blindness s Dry skin and hair s Dry eyes s Defects to developing embryo s Fat Soluble Vitamins Fat s D (Antirachitic factor) s s s s s Functionally a hormone Increases calcium in blood by enhancing Increases absorption absorption Acts with PTH to remove calcium from bones Assists in blood clotting mechanism Deficits s Demineralization of bones and teeth s s Rickets or osteomalacia Restless muscle syndrome Fat Soluble Vitamins Fat s E (Antisterility factor) s s s s Antioxidant for free radicals Prevents oxidation of fatty acids and cholesterol Prevents atherosclerosis Deficits s Possible decrease in life span s K (Coagulation vitamin) s s Formation of clotting proteins Deficits s Easy bruising and prolonged bleeding Easy Protein Catabolism Protein s s s Proteases Peptidases Deamination (removal Deamination of the NH3) of s NH3 becomes urea becomes s Pyruvate, Acetyl CoA, Pyruvate, TCA intermediates are left. left. Transamination Transamination Lipid Catabolism Lipid s Lipolysis s Lipases break lipids Lipases into glycerol (3-C) into s Glycerol enters the Glycerol glycolytic pathway glycolytic s Called β-oxidation Called Beta-Oxidation Beta-Oxidation Synthetic Pathways Synthetic Anabolic reactions synthesize large Anabolic biomolecules biomolecules Unit molecules Glucose Amino Acids Macromolecules nutrients & energy required Polysaccharides Lipids DNA Protein ...
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