7887327-Cellular-Respiration

7887327-Cellular-Respiration - Cellular Respiration Nelson...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Cellular Respiration Nelson Biology Chapter 7 Pages 204 ­ 228 General Learning Outcome • Explain the role of cellular respiration in releasing potential energy from organic compounds Focusing Questions • How is the energy in organic matter released for use by living systems? • How do humans in their application of technologies impact photosynthesis and cellular respirations Importance of Cellular Respiration • Cellular respiration is the process where – cells break down glucose into carbon dioxide and water, releasing energy C6H12O6(s) + O2(g) CO2(g) + H2O(l) + energy Importance of Cellular Respiration • When cells require energy it is supplied by ATP – This is the role of cellular respiration • Both plant and animal cells release energy – Energy is stored in bonds of glucose Electron Carriers • NADH – Donates electrons in cellular processes • NAD+ – Accepts electrons in cellular processes • FADH2 – Donates electrons in cellular processes • FAD+ – Accepts electrons in cellular processes L.E.O. goes G.E.R. • Loss Electrons Oxidation • Gain Electrons Reduction • The transfer of electrons releases energy • This energy can be used to make ATP STOP!! Practice Questions • What is the primary function of cellular respiration? • How do redox reactions in electron transfer help to form ATP? Energy, Cells & ATP Energy, Cells & ATP • Energy for most cellular processes are supplied by: • Typical human cell estimated to contain 1.0x109 molecules ATP – Continually broken down to ADP + Pi – Release energy to do work – Reformed to be used again ATP Active Transport • Used to move substances into or out of the cell • Is against a concentration gradient – Often referred to as “pumps” • Utilizes membrane­bound carrier proteins and energy from ATP Sodium-Potassium Pump Large Scale Motion • Critical use of ATP – Energy from ATP used for movement of muscle Glucose & ATP • ATP not abundant in food – Provide relatively small amounts of energy per molecule Carbohydrates - They are Good! • Most useable source of energy – Notably in the form of glucose • Along with oxygen is a substrate of cellular respiration – Some energy in glucose is converted into ATP ATP is like GOLD • The cell is like a Western amusement park – Operates off gold coins – Stores only accept gold coins Bars vs. Coins • Glucose is like bars of gold – Contains 100x more energy than an individual ATP coin – Have to exchange the bars for coins to be useful • Virtually all process conducted require ATP – ATP is immediate source of energy STOP!! Practice Questions • How do carrier proteins use ATP to transport molecules across the membrane? • One glucose molecule has 100x more stored energy than one ATP molecule. – Why can’t cells use glucose to run their processes? Breaking the Bonds, Releasing the Energy • Respiration ­ chemical bonds of food molecules are broken down – New bonds form in resulting chemical products • ALWAYS takes energy to break chemical bonds • Energy is ALWAYS released when new bonds form • More energy is released than consumed Starting Substance Exchange Rate • Food molecules such as glucose have high energy content – Trade in one $100 gold bar for individual coins • Exchange rate is at best 36% • For every 1 gold bar, will only receive $36 in gold coins – 64% is lost as heat 2 Types of Cellular Respiration • Aerobic Cellular Respiration – Takes place in presence of oxygen – Complete oxidation of glucose • End products: CO2, H2O, 36 ATP molecules • Anaerobic Cellular Respiration – Takes place in absence of oxygen – Glucose not completely oxidized • Broken into 2 main types Aerobic Respiration • • • • Stage 1: glycolysis Stage 2: pyruvate oxidation Stage 3: the Krebs cycle Stage 4: ETC and chemiosmosis C6H12O6 + 6O2 +36ADP +36Pi 6CO2 + 6H2O + 36 ATP Anaerobic Cellular Respiration • Stage 1: glycolysis • Stage 2: fermentation C6H12O6 + 2 ADP + 2 Pi 2C3H6OH + 2CO2 + 2 ATP ethanol C6H12O6 + 2 ADP + 2 Pi 2C3H6O3 + 2 ATP lactic acid Glycolysis • • Greek for “Sugar splitting” Glucose molecule (6 carbon sugar) breaks down to two pyruvate molecules (3 carbon sugar) • • • Takes place without the presence of oxygen Occurs in the cytosol of the cell Pyruvate (pyruvic acid) moves into the mitochondria via a transport protein • Uses a hydrogen carrier NADH • Produces a net of 2 ATP molecules – Also produces two NADH molecules – Photosynthesis uses NADPH Key Steps in Glycolysis 1. Two ATP molecules are used ­ an investment of energy 2. Redox reactions occur ­ 2 positive NAD+ ions remove H+ from the pathway to form 2 NADH molecules 3. Enough energy is released to join 4 ADP molecules with 4 Pi molecules this forms 4 ATP molecules Glycolysis • When complete, cell has • consumed – one glucose molecule and REACTANTS Glucose 2 NAD+ 2 ATP 4 ADP + Pi PRODUCTS 2 pyruvate 2 NADH 2 ADP 4 ATP • produced – two ATP molecules, two NADH molecules and two pyruvate molecules – These ATP molecules are available for cellular functions (the gold coins) Glycolysis 1 glucose + 2 ADP + 2Pi + 2 NAD+ 2 pyruvate + 2 ATP + 2 NADH + 2 H+ • Alone glycolysis is not a highly-efficient energyharnessing mechanism – Transfers only ~2.2% of free energy in glucose to ATP • Some energy released as thermal energy • Majority is trapped in pyruvate and NADH molecules • ALL organisms carry out glycolysis - either as only ATP source or as first step in more energyproductive process – EX. Cellular Respiration RECALL: Aerobic Respiration • Stage 1: glycolysis • Stage 2: pyruvate oxidation • Stage 3: the Krebs cycle – 10 step process in cytoplasm – 1 step process in mitochondria – 8 step cyclical process in mitochondria – Multi­step process in inner mitchondrial membrane • Stage 4: ETC and chemiosmosis C6H12O6 + 6O2 +36ADP +36Pi 6CO2 + 6H2O + 36 ATP Mitochondria ­ Round or sausage­ shaped organelles in cell’s cytoplasm ­ Specialize in large production of ATP ­ Cannot proceed without free oxygen Mitochondrial Powerhouse • Cristae – Folds in inner membrane – Increases surface area – Site of ATP synthesis – Site of the Citric Acid Cycle • Mitochondrial Matrix Stage 2: Pyruvate Oxidation • By the end of Stage 1 cell has formed 2 ATPs, 2 NADHs, and 2 pyruvate molecules Stage 2: Pyruvate Oxidation • Pyruvate oxidation is a chemical pathway connecting glycolysis in cytoplasm with the Kreb’s cycle in the mitochondrial matrix – The 2 pyruvate molecules must be transported through the two mitochondrial membranes into the matrix Key Steps in Pyruvate Oxidation 1. One CO2 is removed from each pyruvate ­ released as a waste product 2. Remaining 2­carbon portions are oxidized by NAD+ 1. 1. Gains 2 H+ (2 protons and 2 electrons) from pyruvate Remaining 2­C compounds become an acetic acid group 1. High energy hydrogens are transferred to NAD+ 3. Coenzyme A (CoA) attaches to acetic acid group ­ forms acetyl­CoA 1. This acetyl­CoA can enter the Krebs cycle Stage 3: the Krebs Cycle Key Features of the Krebs Cycle 1. Krebs cycle occurs twice for eachmolecule of glucose processed 2. Acetyl­CoA enters and releases the CoA, which is recycled for the next pyruvate 3. During one cycle 1. 2. 3. three NAD+s and one FAD are reduced forms three NADHs and one FADH2 one ADP + Pi combine to form one ATP two CO2 molecules are produced and released as waste Key Features of the Krebs Cycle • ALL 6 carbon atoms of glucose have been oxidized to CO 2 – Released from cell as metabolic waste • All that remains is some free energy in form of ATP and high­energy NADH and FADH 2 • NADH and FADH2 go on to Stage 4 – Here much of their energy will be transferred to ATP Stage 4: Electron Transport and Chemiosmosis Stage 4 • Occurs on the inner mitochondrial membranes • NADH and FADH2 eventually transfer the hydrogen atom electrons through the electron transport chain – The energy associated with the electrons pumps H+ ions into the intermembrane space Oxygen - the Final Acceptor • Oxygen accepts the 2 e­ from the final carrier – Also uses 2 H+ ions from the matrix • Forms water H O 2 • This is why all aerobic organisms must obtain oxygen from the environment on a continual basis Chemiosmosis & Oxidative ATP Synthesis • The production of ATP in mitochondria is very similar to that which occurs in the thylakoid membranes in photosynthesis •In photosynthesis, the use of light energy in ATP synthesis is called photosphosphorylation • In cellular respiration, it is referred to as oxidative phosphorylation, or oxidative ATP synthesis • Named because the energy used to drive ATP synthesis comes from the energy released in the ETC ­ from a series of oxidation reactions Where does the ATP go? • After ATP molecules are formed by chemiosmosis they are transported through both mitochondrial membranes – Used to drive processes requiring energy All in the Family • The three stages of aerobic cellular respiration ­ pyruvate oxidation, the Krebs cycle, and ETC & chemiosmosis) are all linked to each other – Dependent on glycolysis for the production of pyruvate Anaerobic Cellular Respiration • Glycolysis changes NAD+ to NADH – Without NAD+ this reaction does not occur • Cells have a limited supply of NAD+ • Without a way to convert NADH to NAD+, glycolysis will come to a halt – ATP no longer will be produced and cell death occurs • Evolved in organisms as a way of recycling NAD+ • One method involves transferring H atoms of NADH to specific organic molecules – Process called fermentation • Lactic acid fermentation • Alcohol fermentation Anaerobic Cellular Respiration – Allows glycolysis to continue Anaerobic Cellular Respiration • Occur in only 2 stages – Glycolysis: same process as that in aerobic cellular respiration – Fermentation: products of glycolysis recycled in 2 different ways • Carbon dioxide and ethanol are final waste products (alcohol fermentation) • Lactic acid is the final waste product (lactic acid fermentation) Alcohol Fermentation • NADH molecules pass their H atoms to acetaldehyde – This forms ethanol • Same type of alcohol used in alcoholic beverages • The 2 ATP produced are enough to satisfy the organism’s energy needs – Recycles NAD+ and allows glycolysis to continue Alcohol Fermentation Application • Can be carried out by a single-celled fungi – Ex. Saccharomyces cerevisiae C6H12O6 + 2 ADP + 2 Pi 2C3H6OH + 2CO2 + 2 ATP ethanol Lactic Acid Fermentation • Under normal conditions, humans obtain energy from glucose by aerobic cellular respiration – During strenuous exercise, the ATP demand is greater than what can be supplied by aerobic respiration alone Lactic Acid Fermentation • NADH transfers its H to pyruvate in the cytoplasm – Regenerates NAD+ – Pyruvate changes into lactic acid Exercise Phsiology • Most common problem faced by athletes shortage of energy – Aerobic fitness factor in judging overall fitness Exercise Phsiology • Muscle cells require energy from ATP • ATP production requires oxygen • Thus assume ATP production increases if more oxygen is absorbed by body cells Maximum Oxygen Consumption • VO2 max – Measure of the body’s ability to generate energy required for activity • You will develop a concept map indicating the criteria for aerobic and anaerobic respiration. This concept map will indicate: – – – – – – – Three similarities between the two processes. Two types of cells that perform each process. Location in the cell where each process occurs. Oxygen requirements for each process. Reactants and products for each process. Energy output for each process. Two different types of anaerobic respiration. • • Reactants and products for each. Types of cells that perform each process. ...
View Full Document

This note was uploaded on 12/04/2009 for the course BIOL 230 taught by Professor Gibson during the Spring '09 term at Tennessee Martin.

Page1 / 60

7887327-Cellular-Respiration - Cellular Respiration Nelson...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online