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High School Biology Unit 3 Cellular Energetics
- 1. Unit 3: CellularEnergetics Cellular Respiration and Photosynthesis
- 2. Chapter 9: CellularRespiration and Fermentation C6H12O6 + 602 6CO2 + 6H2O + ATP becomes oxidized becomes reduced
- 3. Chapter 9: CellularRespiration and Fermentation • The three steps: 1. Glycolysis: occurs in the cytoplasm 2. Citric Acid Cycle: occurs in the matrix 3. Electron Transport Chain: occurs in the inner membrane
- 4. Chapter 9: CellularRespiration and Fermentation • Glycolysis – Where? • cytoplasm – What happens? • Glucose is split into 2 pyruvate molecules • Requires 2 ATP • Substrate level phosphorylation makes 4 ATP • 2 NAD+ pick up H+ from glucose and turn it into 2 NADH ETC – What is produced? • 2 pyruvate molecules • 4 ATP (net gain of 2!!!!) • 2NADH
- 5. Chapter 9: CellularRespiration and Fermentation • Junction between glycolysis and Citric Acid Cycle – Where? • Intermembrane space – What happens? • 2 pyruvates are converted to 2 Acetyl CoA • 2 CO2 are released • 2 NADH are produced ETC – What is produced? • 2 Acetyl CoA • 2 CO2 • 2 NADH
- 6. Chapter 9: CellularRespiration and Fermentation • Citric Acid Cycle (Krebs cycle) – Where? • Mitochondrial matrix – What happens? • 3 CO2 are released (X2) • 3 NADH are produced (X2) • 1 FADH2 is produced (X2) • 1 ATP is produced (X2) – What is produced? • 6 CO2 • 6 NADH • 2 FADH2 • 2 ATP
- 7. Chapter 9: CellularRespiration and Fermentation • Electron Transport Chain – Where? • Inner membrane space – What happens? • NADH drops H+ off at first protein complex • Electrons from H+ are passed from protein to protein; energy from this is used to pump H+ into the intermembrane space • An chemical gradient (chemiosmosis) across the inner membrane with high H+ concentration in the intermembrane space • Electrons join O2 and H+ to make H20 • H+ diffuse through ATP synthase; powering ATP synthesis – What is produced? • H20 • Up to 32 ATP
- 8. Chapter 9: CellularRespiration and Fermentation
- 9. Chapter 9: CellularRespiration and Fermentation
- 10. Chapter 9: CellularRespiration and Fermentation What if there is no oxygen available??!! That’s when fermentation or anaerobic respiration takes place
- 11. Chapter 9: CellularRespiration and Fermentation • Organisms can still go through GLYCOLYSIS Prokaryotes Facultative: not harmed in the presence of oxygen Obligate: will die in the presence of oxygen Only convert pyruvate into ethanol Eukaryotes Animals: pyruvate is converted into lactic acid (helps recycle NAD+) Lactic acid fermentation Yeast: pyruvate is converted to ethanol (helps recycle NAD+) Alcoholic fermentation
- 12. Chapter 9: CellularRespiration and Fermentation
- 13. Chapter 9: CellularRespiration and Fermentation Controlling cellular respiration • Why? – Cells don’t waste energy with overproduction • How? – NEGATIVE FEEDBACK!
- 14. C6H12O6 Pyruvate ATP When more ATP ismade than used, it builds up Excess ATP inhibits an enzyme used in glycolysis. This stops cell respiration until more ATP is needed.
- 15. Chapter 10: Photosynthesis •Who? – Autotrophs (plants, photosynthetic protists, cyanobacteria) • What? – Converting solar energy (sunlight) to chemical energy (carbohydrates) • How? – 6CO2 + 12H2O C6H12O6 + 6H2O +6O2
- 16. Chapter 10: Photosynthesis •Green portions of autotrophs (i.e. leaves) serve as the site for photosynthesis
- 17. Chapter 10: Photosynthesis •Stomata: – Pores on the bottom of the leaf that allow water out (helps with transpiration) – Will close if conditions are too dry to prevent water loss – Also allows CO2 into the leaf
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- 20. Chapter 10: Photosynthesis Light Reactions •Produce ATP and NADPH in the thylakoids Calvin Cycle • Reduces CO2 to a carbohydrate in the stroma
- 21. Chapter 10: Photosynthesis •The light reactions: – Use pigments (chlorophyll and carotenoids) to absorb visible light – Two photosystems (II and I) gather solar energy to make ATP and NADPH
- 22. Chapter 10: Photosynthesis •Photosystem II (P680) – Electrons in chlorophyll are excited by sunlight – The excited electrons are captured by a primary electron acceptor – Water splits in order to replenish the lost electrons; releasing oxygen – These electrons enter an electron transport chain creating a H+ gradient – The result? • ATP is produced!!!!
- 23. Chapter 10: Photosynthesis •Photosystem I (P700) – As sunlight excites the second photosystem, a new set of electrons enter another electron transport chain – Electrons from PSII replenish these – Newly energized electrons pass to NADP+ – The result? • NADPH is produced!
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- 25. Chapter 10: Photosynthesis •Calvin Cycle 1. CO2 fixation • One molecule of CO2 is converted to two 3- carbon compounds with the help of RuBP 2. CO2 reduction • ATP and electrons from NADPH (from the light reactions) are used to create 3-carbon sugars 3. Regeneration of RuBP • The enzyme that fueled step one must be recycled
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- 28. Work with apartner to complete the graphic organizer in your note packet.
- 29. Chapter 10: Photosynthesis •The evolution of photosynthesis…. – Not all climates are considered equal – Different adaptations have developed for plants in different environments When might this be a problem?
- 30. • Photosynthetic activitydeclines on hot, dry days because stomata close • Oxygen builds up binding with Rubicsco photorespiration (uses ATP and produces no sugar) • Rice, wheat, maples, tulips C3 Plants • The light reactions and the Calvin cycle take place in different cells (mesophyll cells and bundle sheath cells respectively) • This separates Rubisco from O2 preventing photorespiration • Sugarcane, corn, grass C4 Plants • Close stomata during the day to conserve water; open only at night • Stores CO2 it absorbs during the night as crassulacean acid and releases it as CO2 during the day when photosynthesis can occur • Cacti, pineapple CAM plants