* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slide 1
Butyric acid wikipedia , lookup
Metalloprotein wikipedia , lookup
Mitochondrion wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Basal metabolic rate wikipedia , lookup
NADH:ubiquinone oxidoreductase (H+-translocating) wikipedia , lookup
Phosphorylation wikipedia , lookup
Nicotinamide adenine dinucleotide wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Photosynthesis wikipedia , lookup
Electron transport chain wikipedia , lookup
Microbial metabolism wikipedia , lookup
Light-dependent reactions wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Citric acid cycle wikipedia , lookup
TO DO- check it out! • http://www.khanacademy.org/ This vast website has many short lectures on various aspects of Biology. They will help with your understanding of difficult concepts. HOW CELLS HARVEST CHEMICAL ENERGY (CELLULAR RESPIRATION) Important points to review…. • Energy is one-way flow. • Energy is not created or destroyed it can only be converted from one form to another. Solar energy (sun) Chemical energy (stored in glucose molecule) Overview Photosynthesis Reaction: 6CO2 + 12 H2O C6H12O6 + 6O2 + 6 H2O 2nd Important Energy Reaction Overview Cellular Respiration Reaction: C6H12O6 + 6O2 6CO2 + 6 H2O + (32 ATP) Cellular respiration is an exergonic process that transfers energy from the bonds in glucose to form ATP. Photosynthesis and cellular respiration provide energy for life - 4 important points 1. 2. 3. 4. © 2012 Pearson Education, Inc. Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts The connection between photosynthesis and cellular respiration CO2 Glucose H2O O2 Cellular respiration in mitochondria (for cellular work) ATP Heat energy Breathing supplies O2 for use in cellular respiration and removes CO2 O2 The connection between breathing and cellular respiration Breathing CO2 Lungs CO2 Bloodstream O2 Muscle cells carrying out Cellular Respiration Glucose O2 CO2 H2O ATP CONNECTION: The human body uses energy from ATP for all its activities The average adult human needs about 2,200 kcal (the same as a food Calorie) of energy per day. – About 75% of these calories are used to maintain a healthy body. – The remaining 25% is used to power physical activities. Cells tap energy from electrons “falling” from organic fuels to oxygen The energy necessary for life is contained in the arrangement of electrons in chemical bonds in organic molecules. An important question is how do cells extract this energy? – When the carbon-hydrogen bonds of glucose are broken, electrons are transferred to oxygen. – Oxygen has a strong tendency to attract electrons. – An electron loses potential energy when it “falls” slowly to oxygen. That energy can be picked up by ATP! Cells tap energy from electrons “falling” from organic fuels to oxygen Energy can be released from glucose by simply burning it. The energy is dissipated as heat and light and is not available to living organisms. On the other hand, cellular respiration is the controlled breakdown of organic molecules. Summation: Energy is – ___________________________________ – ___________________________________ – ___________________________________ Cells tap energy from electrons “falling” from organic fuels to oxygen The movement of electrons from one molecule to another is an oxidation-reduction reaction, or redox reaction. Cells tap energy from electrons “falling” from organic fuels (glucose) to oxygen Enzymes are necessary to oxidize glucose and other foods. NAD+ – is an important enzyme in oxidizing glucose, – accepts electrons, and – becomes reduced to NADH. Cells tap energy from electrons “falling” from organic fuels to oxygen There are other electron “carrier” molecules that function like NAD+. – They form a staircase where the electrons pass from one to the next down the staircase. – These electron carriers collectively are called the electron transport chain. – As electrons are transported down the chain, ATP is generated. Overview: Cellular respiration occurs in three main stages Cellular respiration consists of a sequence of steps that can be divided into three stages. – Stage 1 – ______________________ – Stage 2 – ______________ and ___________________ – Stage 3 – ______________________ Mitochondria Overview: Cellular respiration occurs in three main stages Stage 1: Glycolysis Glycolysis harvests chemical energy by oxidizing glucose to pyruvate In glycolysis, – a single molecule of ____________ is enzymatically cut in half through a series of steps, – two molecules of _____________ are produced, – two molecules of NAD+ are reduced to two molecules of ____________, and – a net of two molecules of _________ is produced. P P NAD NAD P NADH P NADH H H P P P ADP P 1,3-Bisphosphoglycerate P 3-Phosphoglycerate ADP 6 ATP ATP P P P 2-Phosphoglycerate H2O H2O P P ADP ATP ADP Phosphoenolpyruvate (PEP) ATP Pyruvate Glycolysis harvests chemical energy by oxidizing glucose to pyruvate The steps of glycolysis can be grouped into two main phases. – In steps 1–4, the energy investment phase, – energy is consumed as two ATP molecules are used to energize a glucose molecule, – which is then split into two small sugars that are now primed to release energy. – In steps 5–9, the energy payoff, – two NADH molecules are produced for each initial glucose molecule and – 4 ATP molecules are generated. (net gain of 2!) Glycolysis harvests chemical energy by oxidizing glucose to pyruvate ATP is formed in glycolysis by substrate-level phosphorylation during which – an enzyme transfers a ____________ group from a substrate molecule to ADP and – ATP is formed. Overview: Cellular respiration occurs in three main stages Stage 2: The citric acid cycle Pyruvate is oxidized prior to the citric acid cycle Two molecules of pyruvate are produced for each molecule of glucose that enters glycolysis. Pyruvate does not enter the citric acid cycle, but undergoes some chemical grooming in which – a carboxyl group is removed and given off as _______, – the two-carbon compound remaining is oxidized while a molecule of NAD+ is reduced to __________, – coenzyme A joins with the two-carbon group to form acetyl coenzyme A, abbreviated as acetyl CoA, and – acetyl CoA enters the citric acid cycle. The citric acid cycle completes the oxidation of organic molecules, generating many NADH and FADH2 molecules The citric acid cycle – is also called the Krebs cycle (after the German-British researcher Hans Krebs, who worked out much of this pathway in the 1930s), – completes the oxidation of organic molecules (glucose), and – generates many NADH and FADH2 molecules. Acetyl CoA During the citric acid cycle the two-carbon group of acetyl CoA is added to a four-carbon compound, forming citrate, citrate is degraded back to the four-carbon compound, two CO2 are released, and ___ ATP, ___ NADH, and __-FADH2 are produced. CoA CoA 2 CO2 Citric Acid Cycle 3 NAD FADH2 3 NADH FAD 3 H ATP ADP P The citric acid cycle completes the oxidation of organic molecules, generating many NADH and FADH2 molecules Remember that the citric acid cycle processes two molecules of acetyl CoA for each initial glucose. Thus, after two turns of the citric acid cycle, the overall yield per glucose molecule is – 2 ATP, – 6 NADH, and – 2 FADH2. Acetyl CoA CoA CoA 2 carbons enter cycle Oxaloacetate 1 Citrate NADH H NAD 5 NAD NADH 2 H Citric Acid Cycle CO2 leaves cycle Malate FADH2 Alpha-ketoglutarate 4 3 FAD CO2 leaves cycle NAD Succinate ADP Step 1 Acetyl CoA stokes the furnace. P Steps 2 – 3 ATP NADH, ATP, and CO2 are generated during redox reactions. NADH H Steps 4 – 5 Further redox reactions generate FADH2 and more NADH. Overview: Cellular respiration occurs in three main stages Stage 3: Oxidative phosphorylation Use _____________ and __________ already formed in previous stages Produce ___ ___ ___ Most ATP production occurs by oxidative phosphorylation Electrons from NADH and FADH2 travel down the electron transport chain to ______. Oxygen picks up H+ to form water. Energy released by these redox reactions is used to pump H+ from the mitochondrial matrix into the intermembrane space. In __________________, the H+ diffuses back across the inner membrane through ________________complexes, driving the synthesis of ATP. H Intermembrane space H H H H Mobile electron carriers Protein complex of electron carriers H ATP synthase IV I II FADH2 Electron flow NADH Mitochondrial matrix H H III Inner mitochondrial membrane H NAD FAD 2 H 1 2 O2 H2O H ADP P ATP H Electron Transport Chain Oxidative Phosphorylation Chemiosmosis Review: Each molecule of glucose yields many molecules of ATP Recall that the energy payoff of cellular respiration involves – glycolysis, – alteration of pyruvate, – the citric acid cycle, and – oxidative phosphorylation. The total yield is about 32 ATP molecules per glucose molecule. This is about 34% of the potential energy of a glucose molecule. In addition to the ATP, _______and _______are produced. https://Cellular Respiration Rap CYTOPLASM Electron shuttles across membrane 2 NADH Mitochondrion 2 NADH or 2 FADH2 6 NADH 2 NADH Glycolysis 2 Pyruvate Glucose Pyruvate Oxidation 2 Acetyl CoA Citric Acid Cycle 2 FADH2 Oxidative Phosphorylation (electron transport and chemiosmosis) Maximum per glucose: 2 ATP by substrate-level phosphorylation 2 ATP by substrate-level phosphorylation about 28 ATP by oxidative phosphorylation About 32 ATP http://Cellular Respiration Animation Watch it until it makes sense! Glycolysis - Fermentation Animation Fermentation enables cells to produce ATP without oxygen Fermentation is a way of harvesting chemical energy that does not require oxygen. Fermentation – takes advantage of glycolysis….so.. – produces _____ ATP molecules per glucose, and – reduces NAD+ to _________. The trick of fermentation is to provide an anaerobic path for recycling NADH back to NAD+. Your muscle cells and certain bacteria can oxidize NADH through lactic acid fermentation, in which NADH is oxidized to NAD+ and pyruvate is reduced to lactate. The baking and winemaking industries have used alcohol fermentation for thousands of years. In this process yeasts (single-celled fungi)oxidize NADH back to NAD+ and convert pyruvate to CO2 and ethanol. Animation: Fermentation Overview Right click on animation / Click play EVOLUTION CONNECTION: Glycolysis evolved early in the history of life on Earth Glycolysis is the universal energy-harvesting process of life. The role of glycolysis in fermentation and respiration dates back to – life long before oxygen was present, – when only prokaryotes inhabited the Earth, – about 3.5 billion years ago. The ancient history of glycolysis is supported by its – occurrence in all the domains of life and – location within the cell, using pathways that do not involve any membrane-bounded organelles. Cells use many kinds of organic molecules as fuel for cellular respiration Although glucose is considered to be the primary source of sugar for respiration and fermentation, ATP is generated using – carbohydrates, – fats, and – proteins. © 2012 Pearson Education, Inc. Food, such as peanuts Carbohydrates Sugars Fats Proteins Glycerol Fatty acids Amino acids Amino groups Glucose G3P Pyruvate Glycolysis Pyruvate Oxidation Acetyl CoA ATP Citric Acid Cycle Oxidative Phosphorylation Food molecules provide raw materials for biosynthesis Cells use intermediates from cellular respiration for the biosynthesis of other organic molecules. You should now be able to 1. Compare the processes and locations of cellular respiration and photosynthesis. 2. Explain how breathing and cellular respiration are related. 3. Provide the overall chemical equation for cellular respiration. 4. Explain how the human body uses its daily supply of ATP. You should now be able to 5. Explain how the energy in a glucose molecule is released during cellular respiration. 6. Describe the general roles of dehydrogenase, NADH, and the electron transport chain in cellular respiration. 7. Compare the reactants, products, and energy yield of the three stages of cellular respiration. You should now be able to 9. Compare the reactants, products, and energy yield of alcohol and lactic acid fermentation. 10. Briefly explain how carbohydrates, fats, and proteins are used as fuel for cellular respiration. Aerobic respiration…… an animation to help you visualize http://www2.nl.edu/jste/aerobic_respiration.htm Cellular respiration has three stages generates oxidizes uses produce some produces many energy for glucose and organic fuels (a) (b) (d) to pull electrons down (c) cellular work (f) by a process called chemiosmosis uses (g) H diffuse through ATP synthase (e) uses pumps H to create H gradient to Proton Pump/Chemiosmosis AN OVERVIEW OF AEROBIC RESPIRATION