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CP BIO Chapter 9 Cellular Respiration

CP BIO Chapter 9 Cellular Respiration. How Cells Harvest Chemical Energy. All life activities need energy. CP BIO: Ch. 9 Cell Respiration. a. Maintain homeostasis ; do life functions breathe, circulate blood active transport, synthesize molecules regulate temperature, etc.

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CP BIO Chapter 9 Cellular Respiration

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  1. CP BIOChapter 9Cellular Respiration How Cells Harvest Chemical Energy

  2. All life activities need energy CP BIO: Ch. 9 Cell Respiration • a. Maintain homeostasis; do life functions • breathe, circulate blood • active transport, synthesize molecules • regulate temperature, etc. • b. Physical and mental activity • c. Cells use energy in ATP molecules

  3. Food energy is measured in calories calorie = energy needed to raise the temperature of one mL water 1 degree Celsius Food labels: Calorie (Kcal) = 1000 calories

  4. Gas exchange is by diffusion In the lungs: Oxygen from air - diffuses into blood - carried to body cells Carbon dioxide from blood - diffuses into air sacs - removed from body

  5. Cells need oxygen for respiration In cells: - oxygen diffuses IN - CO2 goes OUT

  6. All organisms do respiration • Need oxygen - aerobic • No oxygen - anaerobic Energy flow is one-way - sun plants  ATP Chemicals recycle

  7. Basics of Cellular Respiration • Breaks down glucose in many small steps • a biochemical pathway • Energy released is stored in molecules of ATP • Each ATP has enough energy for one cell task • One glucose molecule yields 36 ATP

  8. Electron Acceptors • Help in reaction pathway, re-used • 2 in respiration: NAD and FAD • Accept hydrogen ions and electrons from glucose as it breaks down • Transfer them to another molecule later in pathway • makes ATP

  9. Mitochondria – “power house” Compartments - for different stages • Matrix • Space enclosed by inner membrane • Inner membrane • Deeply folded, more surface • Many reactions at the same time • Cristae - folds in membrane • Intermembrane space • Between inner and outer membrane

  10. Oxygen and Energy Aerobic respiration harvests the most ATP from glucose AerobicAnaerobic Breaks down glucose completely Glucose partly broken down Yields max amount of ATP Yields 2 ATP/glucose Most organisms Only a few microorganisms 3 stages of breakdown 2 stages of breakdown Glycolysis Glycolysis Kreb’s cycle Fermentation Electron Transport Chain

  11. Stages of Cell Respiration • Glycolysis • In cytoplasm • Splits glucose in half • Kreb’s Cycle • In mitochondria • Finishes glucose breakdown • 3. Electron Transport Chain • In mitochondria • Generates the most ATP

  12. Glycolysis 1st stage in cell respiration Glycolysis = “sugar splits” Glucose  two smaller molecules small amount of energy released Need 2 ATP to start a. Two ATP attach to glucose b. glucose splits in two c. 3-carbon PGAL forms d. PGAL goes through several more reactions

  13. Glycolysis breakdown • Each PGAL loses hydrogen to NAD+ a) makes NADH b) PGAL changes to pyruvic acid 2) 4 ATP are produced, but net yield is 2 Products of glycolysis: 1) 2 ATP 2) 2 NADH 3) 2 pyruvic acid

  14. All organisms do glycolysis • Need no oxygen or special organelles • Probably evolved very early in history of life • Can meet energy needs of some simple organisms

  15. Sir Hans Krebs 1900-1981 • German chemist, 1930s • Described the cycle of reactions that make energy in cells • Received Nobel in 1953 • “Krebs Cycle” or “Citric Acid Cycle”

  16. Pyruvic Acid Breakdown PREPARES pyruvic acid for Kreb’s cycle NOT a separate stage • Hydrogen removed  NADH • Carbon removed  CO2 • Acetyl-CoA forms • Ready for Kreb’s cycle

  17. Kreb’s Citric Acid Cycle Stage 2 in aerobic respiration In MATRIX Completes breakdown of glucose to carbon dioxide Makes many molecules of NADH and FADH2 (make energy later)

  18. Products of Kreb’s Cycle • 2 ATP/glucose molecule (one each “turn”) 2. Several molecules of NADH and FADH2 • These will yield energy in stage 3 3. Last carbons in glucose form CO2 and diffuse out of cell

  19. Electron Transport ChainStage 3 in aerobic respiration MOST ATP made here What is it? • Chain of proteins in inner membrane (cristae) • Transfer electrons • Electron energy makes ATP • Only happens if oxygen is available to take • electrons at end of chain and form WATER • O + 2 H+ + 2 e- H2O

  20. Electrons power ATP synthaseenzyme makes ATP • Total ATP yield per glucose: • Glycolysis – 2 ATP • Krebs – 2 ATP • ETC - 32 ATP • Total = 36 ATP

  21. Summary of Aerobic Respiration

  22. Anaerobic Respiration FERMENTATION follows glycolysis • Needs no oxygen • Makes no additional ATP after glycolysis • NAD+ is reused • Pyruvic acid is changed into a final product

  23. 0 Fermentation: two kinds Alcohol lactic acid

  24. Alcohol Fermentation • Some yeasts • pyruvic acid  ethyl alcohol + CO2 • Baking, brewing beer and wine • CO2 gas makes bread dough rise, bubbles in beer and champagne No more ATP made

  25. Lactic Acid Fermentation • Pyruvic acid  lactic acid • Anaerobic bacteria -make lactic (and other) acids • Commercial uses: cheese, yogurt, soy products, sauerkraut, vinegars • Muscle cells – can do fermentation only temporarily • lactic acids builds up  “oxygen debt” • Muscles fatigue, cramp • With fresh oxygen: Lactic acid  blood  liver, changed back to pyruvic acid  Kreb’s cycle

  26. Other foods in respiration • Carbs are #1 choice for cell energy: 4 cal/g • Fats: twice the calorie store: 9cal/g • Proteins: LAST choice: • – needed for many important roles • 4 cal/g • Fats and proteins are also broken down in many small steps • Amount of ATP depends on molecule

  27. Photosynthesis and Respiration Photosynthesis – makes food Light energy  chemical energy 6 H2O + 6 CO2 C6 H12 O6 + 6 O2 Respiration – breaks down food for cell energy C6 H12 O6 + 6 O2  6 H2O + 6 CO2 Energy in food  energy in ATP

  28. Breathing supplies oxygen to cells 1) Breathing brings oxygen into the body 2) Oxygen in lungs diffuses into blood 6) Blood carries CO2 back to lungs - exhaled 5) CO2 diffuses out of cells into blood 3) Blood delivers oxygen to all body cells 4) Oxygen is used in cell respiration.

  29. Pyruvic acid is broken down to CO2 and acetyl (2-C) • -- joins to coenzyme A 2) starting molecule – acetyl CoA 4. Carbon “fixed”  6 C citric acid 3) 4-C compound in matrix 8) 4-C compound recycled 5) two carbons  CO2 7) hydrogens removed - NAD, FADH reduced 6) one ATP forms

  30. Chemiosmosis 6) Final electron acceptor is oxygen O + H+ + e-  H2O 5) ADP + P  ATP 1)Starting molecules NADH, FADH2 release H+ and electrons 2)Electrons pass from one protein in transport chain to next 4) H+ ions diffuse through ATP synthase (chemiosmosis) 3)Electron energy pumps H+ across membrane - Forms H+ gradient

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