MC 101 - LP - Bioenergetics PDF

BIOENERGETICS MC 101 – LP - BIOCHEMISTRY Define metabolism and differentiate catabolism from anabolism. Discuss the Citric Acid Cycle and its significance. Discuss the electron and proton transport and their physiological roles. Explain chemiosmotic pump theory and the production of energy. LEARN...

BIOENERGETICS MC 101 – LP - BIOCHEMISTRY Define metabolism and differentiate catabolism from anabolism. Discuss the Citric Acid Cycle and its significance. Discuss the electron and proton transport and their physiological roles. Explain chemiosmotic pump theory and the production of energy. LEARNING OBJECTIVES What is Bioenergetics? The study of energy in living systems (environments) and the organisms (plants and animals) that utilize them Energy Required by all organisms May be Kinetic or Potential energy Kinetic Energy Energy of Motion Heat and light energy are examples Potential Energy Energy of position Includes energy stored in chemical bonds  Two Types of Energy Reactions  Endergonic Reactions Chemical reaction that requires a net input of energy. Photosynthesis Light SUN Energy photons 6CO2 + 6H2O C6H12O6 + 6O2 (glucose) 8 Exergonic Reactions Chemical reactions that releases energy Cellular Respiration Energy C6H12O6 + 6O2 6CO2 + 6H2O+ ATP (glucose) 9  Metabolic Reactions of Cells What is Metabolism? The sum total of the chemical activities of all cells. 11 Two Types of Metabolism oAnabolic Pathways oCatabolic Pathways 12  Anabolic Pathway Metabolic reactions, which consume energy (endergonic), to build complicated molecules from simpler compounds. Photosynthesis SUN light energy 6CO2 + 6H2O C6H12O6 + 6O2 (glucose) 13  Catabolic Pathway Metabolic reactions which release energy (exergonic) by breaking down complex molecules in simpler compounds Cellular Respiration energy C6H12O6 + 6O2 6CO2 + 6H2O + ATP (glucose) 14 Cellular Energy - ATP COPYRIGHT CMASSENGALE  ATP Components: 1. adenine: nitrogenous base 2. ribose: five carbon sugar 3.phosphate group: chain of 3 adenine phosphate group P P P ribose 16  Adenosine Triphosphate Three phosphate groups-(two with high energy bonds Last phosphate group (PO4) contains the MOST energy 17  Breaking the Bonds of ATP Process is called phosphorylation Occurs continually in cells Enzyme ATP-ase can weaken & break last PO4 bond releasing energy & free PO4 18  How does ATP work ? Organisms use enzymes to break down energy-rich glucose to release its potential energy This energy is trapped and stored in the form of adenosine triphosphate(ATP) 19 How Much ATP Do Cells Use? It is estimated that each cell will generate and consume approximately 10,000,000 molecules of ATP per second 20  Coupled Reaction - ATP The exergonic hydrolysis of ATP is coupled with the endergonic dehydration process by H 2O transferring a phosphate group to another molecule. H 2O 21  Hydrolysis of ATP ATP + H2O ADP + P (exergonic) Adenosine triphosphate (ATP) P P P Hydrolysis (add water) + P P P Adenosine diphosphate (ADP) 22 Hyrolysis is Exergonic Energy Used by Cells 23 Dehydration of ATP ADP + P ATP + H2O (endergonic) Dehydration (Remove H2O + P P P Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) P P P 24 Dehydration is Endergonic Energy is restored in Chemical Bonds 25  Nicotinamide H O NAD+, Nicotinamide Adenine Adenine C NH 2 Dinucleotide, is an electron acceptor Dinucleotide O in catabolic pathways.  + N nicotinamide O P O CH2 O The nicotinamide ring, derived from H H the vitamin niacin, accepts 2 e- & 1 H+ H OH OH H (a hydride) in going to the reduced O NH 2 state, NADH. N N NADP+/NADPH is similar except for Pi. NADPH is e donor in synthetic  O P O CH2 N O N adenine pathways. O H H H H esterified to OH OH Pi in NADP+ NAD+/NADH H O O H H C C NH2 NH2 + N  2 e + H+ N R R NAD+ NADH The electron transfer reaction may be summarized as : NAD+ + 2e + H+  NADH. It may also be written as: NAD+ + 2e + 2H+  NADH + H+  dimethylisoalloxazine O O H H H C N C  + C N C H3C C C C NH 2e +2H H3C C C C NH H3C C C C C O H3C C C C C O C N N C N N H H H CH2 CH2 HC OH HC OH HC OH HC OH FAD Adenine FADH2 HC OH O O Adenine HC OH O O H2C O P O P O Ribose H 2C O P O P O Ribose O- O- O- O- FAD (Flavin Adenine Dinucleotide), derived from the vitamin riboflavin, functions as an e acceptor. The dimethylisoalloxazine ring undergoes reduction/oxidation. FAD accepts 2 e + 2 H+ in going to its reduced state: FAD + 2 e + 2 H+  FADH2 NAD+ is a coenzyme, that reversibly binds to enzymes. FAD is a prosthetic group, that remains tightly bound at the active site of an enzyme. The citric acid cycle enzymes are found in the matrix of the mitochondria Substrates have to flow across the outer and inner parts of the mitochondria TCA – Net Output Each triboxylic cycle produces: Two molecules of carbon dioxide. Three molecules of NADH. Three hydrogen ions (H+). One molecule of FADH₂ One molecule of GTP (Guanosine-5'-triphosphate) Each molecule of glucose produces two molecules of pyruvate, which in turn produce two molecules of acetyl-coA. Therefore, each molecule of glucose produces double the net output of each cycle. Regulation of the TCA Cycle The TCA Cycle is regulated in a variety of ways: Metabolites: Products of the cycle provide negative feedback on the enzymes that catalyse it. For example, NADH inhibits the majority of the enzymes found in the TCA cycle. Citrate: Inhibits phosphofructokinase, a key enzyme in glycolysis. This reduces the rate of production of pyruvate and therefore of acetyl-coA. Calcium: Accelerates the TCA cycle by stimulating the link reaction.  ETC The final stage of aerobic respiration is the electron transport chain, which is located on the inner mitochondrial membrane The inner membrane is arranged into folds (cristae), which increases the surface area available for the transport chain The electron transport chain releases the energy stored within the reduced hydrogen carriers in order to synthesize ATP This is called oxidative phosphorylation, as the energy to synthesize ATP is derived from the oxidation of hydrogen carriers Oxidative phosphorylation occurs over a number of distinct steps: One glucose molecule is metabolized to yield 38 ATP molecules during cellular respiration. The electron transport system produces 34 molecules of ATP out of a total of 38 molecules. THANK YOU