Bioenergetics Learning Goals. 1. Understand laws of thermodynamics and how they relate to biological systems 2. Understand that organisms are interdependent, open systems that respond to their environment by managing their energy resources
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Bioenergetics Learning Goals 1. Understand laws of thermodynamics and how they relate to biological systems 2. Understand that organisms are interdependent, open systems that respond to their environment by managing their energy resources 3. Understand how mitochondria and chloroplasts work with the cell to harvest chemical energy, or convert solar energy to chemical energy 4. Understand the fundamental cellular process of chemiosmosis and its central role in ATP production
The Good News: You know most of this stuff already Enzymes Semipermiable Membranes Active Transport Potential/Kinetic/ Chemical Energy Macromoleules/Mono- mers ATP Kinases Metabolism The New Ideas: Catabolism and Anabolism The Stages of Cellular Respiration Chemiosmosis Oxidative Phosphorylation Light Dependent/Light Independent Reactions Photophosphorylation Metabolism/Cellular Energetics(The central concept of Semester 1)
Key Concepts • Metabolism • Energy: Free Energy: • Spontaneous vs. non spontaneous reactions • ATP couples Reactions • Dynamic Equilibrium
College Board “Performance Objectives” • Describe the role of ATP in coupling a cell’s catabolic and anabolic reactions. • Explain how chemiosmosis functions in bioenergetics • How are organic molecules broken down by the catabolic pathways of cellular respiration • Explain the role of oxygen in energy-yielding pathways of cellular respiration • Explain how cells generate ATP in the absence of oxygen.
Definitions • Metabolism: • Metabolic Pathway: • Catabolism: • Anabolism:
Energy • Energy: • Kinetic Energy: • Potential Energy: • Chemical Energy
The laws of energy transformation • 1st Law of Thermodynamics: (pg. 143) • 2nd Law of Thermodynamics:
More definitions • Free Energy: • Exergonic = • Endergonic =
How does this apply to Biological Systems? A or BS: C:
How are Catabolism and Anabolism “coupled”? The hydrolysis of ATP yields 7.3kCal/mole of ATP
How does ATP Perform Work? ATP Phosphorylates other molecules!
Bioenergetics: The Big Picture • Producers • Consumers
Bioenergetics: The Big Picture • The Equations: • In general… • Organic Molecules • Food • Combustion or Oxidation of Glucose (∆G) = • Number of ATP/Glucose Molecule • Regeneration of ATP (from ADP & Pi) (∆G) =
Consumers (start with organic molecules, give off CO2) • Some Details: Glycolysis • FermentationCellular Respiration These are re-dox reactions
Cellular Respiration • Oxidation of Food Molecules by Oxygen • Releases Energy • Cumulative Function of 3 metabolic stages • Glycolysis • Citric Acid (Kreb’s) Cycle • Oxidative Phosphorylation
Our Objective • Learn the important details about the 3 metabolic stages of cellular respiration • Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation • Remember that the cell is using glucose to make ATP (it’s harvesting energy) • Remember these stages are connected!
Glycolysis Fig 9.8 • Literally… • (2 phases)
Glycolysis 1: Energy Investment • What happens, why? • What’s the “end” product?
Glycolysis 2: Energy Return • G3P is… • SLP… • The “end” product(s): • ATP • NADH • Pyruvate
Citric Acid Cycle: • It is a cycle! • Where does it happen? • What are the outcomes? Citrate (6-C) Oxaloacetate (4-C)
Citric Acid Cycle:The Bottom Line… Pyruvate is completely oxidized and the energy is converted to NADH and FADH2 (ETC) and ATP via S.L.P. 8 NADH and 2 FADH2 per glucose molecule The intersection between Glycolysis and OXY PHOS
Oxidatative Phosphorylation Overview: During oxidative phosphorylation, chemiosmosis couples electron transport to ATP Synthesis.
Oxidative Phosphorylation 1:E.T.C. • Where? • What? • How? • What else happens? P.C.
Oxidative Phosphorylation 2 • So What? • E.T.C. drives… • ATP Synthase
Oxidative Phosphorylation 3: Putting it all together 1) 2) 3) Chemiosmosis! An energy-coupling mechanism that uses energy stored in the form of a H+ gradient across a membrane to drive cellular work. [ ] 2) 3) 1) [ ]
Hints for building ETC Model • Start with aligning yourselves from least electronegative (greatest Potential energy) to most electronegative. This should be a physical change in height. Use stools, chairs, bench tops etc. • Get comfortable passing electrons down from least electronegative molecule to most electronegative molecule. (I suggest saying “Grrrr” when you get reduced. Perhaps the “Grrr” gets louder as electo-negativity increases.) • Once you are comfortable passing electrons, add in the protons moving across the protein complexes, into the intermembrane space and then through ATP synthase to generate ATP. • Use your textbook, each other, and me as a resource. I will be videotaping the process and product.
Cellular Respiration: Review (F9.16)(don’t look at the book, let’s work this out together.) Reactants, Products, major intermediates, processes, specific locations Net ATP Production Mode of ATP Production
ATP Accounting? ATP/NADH ATP/FADH2 ATP/H+ • Catabolism of Glucose, ∆G = -686 kCal/mol • Anabolism of ATP from ADP + Pi, ∆G = 7.3 kCal/mol • About 36-38 mol ATP/mol glucose • ATP synthesis is roughly… …efficient • Where does the rest of the energy go?
Fermentation: an alternate pathway for energy production (ATP synthesis) • Fermentation is… • fermentation starts with... • F.A… • O.A…
Fermentation: (2 processes) • What do these pathways have in common? • What’s different? • What’s the significance of alcohol fermentation? • What’s the significance of lactic acid fermentation? • What else do these pathways have in common?
Comparing Fermentation and Cellular Respiration • Commonalities: • Differences: Oxidative Phosphorylation
Glycolysis is ancient… • How old is it? • Est. to be ________ • What else do we know
Enzymatic Regulation:Allosteric RegulationFluctuating concentrations ATP vs. ADP + Pi