Respiration..... It ain't just breathin' anymore!!

1. Respiration..... It ain't just breathin' anymore!!

2. How Do Organisms Supply Themselves With Energy?

3. Key Questions • How do organisms supply themselves with energy? • How do organisms extract energy from glucose? • How is the energy in glucose used to make ATP?

4. How Do Organisms Supply Themselves With Energy? • All organisms need energy • Ultimate source of energy on the Earth is the sun • Autotrophs make their own food; • examples: plants, some bacteria • Heterotrophs obtain chemical energy from other organisms • Examples?

5. Energy Currency • Adenosine Triphosphate or ATP • Cellular respiration produces ATP • Aerobic versus anaerobic

6. Cellular Respiration

7. Steps of Cellular Respiration • Step 1: glycolysis • Step 2: acetyl-CoA formation • Step 3: citric acid cycle • Step 4: electron transport and oxidative phosphorylation

8. Cellular Respiration — Chemical Equation • C6H12O6 + 6O2 Glucose Oxygen • 6CO2 + 6H2O + ATP Carbon Water Energy Dioxide

9. What Is Oxidation? • Oxidizing agent or electron acceptoraccepts an electron • Reducing agent or electron donor donates an electron • Oxidation and reduction always go hand in hand • Examples of acceptors: O2, NAD+, FAD

10. Step 1: GlycolysisOccurs in Cytoplasm • Part 1: 6- carbon Glucose split into two 3-carbon molecules and are phosphorylated; uses ATP • Part 2: Phosphates and electrons are removed; electrons added to NAD+ to make NADH; produces 2 ATP

11. Step 1: Glycolysis Cont. • Part 3: • More electrons and phosphates are removed from the two 3-carbon molecules; • phosphates are added to ADP to make ATP

12. Glycolysis Overview • Breaks glucose into 2 molecules of pyruvate, generating 2 molecules of ATP and 2 molecules of NADH • Aerobic or anaerobic? • The pyruvate enters a cell’s ______. • When compounds are reduced, they ___ electrons. • When compounds are oxidized, they ___ electrons. • Which molecules/coenzymes from Glycolysis accept electrons? ANAEROBIC MITOCHONDRIA ACCEPT DONATE NAD+

13. Step 2: Acetyl CoAOccurs in ______ MITOCHONDRIA • Oxygen needed for this reaction; aerobic • Pyruvate loses a carbon and 2 oxygens in the form of CO2 • Enzymes link coenzyme A to the acetate • CoA synthesizes fatty acids.

14. Step 3: Citric Acid CycleOverview • High energy electrons are captured in the form of NADH and FAD • Occurs in the matrix of the mitochondria • With each turn of the cycle, citrate loses a total of 8 electrons to electron acceptors such as NAD+

15. Step 3: Citric Acid Cycle • 3 parts • Part 1: 6-carbon citrate and isocitrate formation • Part 2: conversion of isocitrate into a 4-carbon compound • Part 3: production of another molecule of OAA, which starts the cycle over again

16. Citric Acid Cycle

17. What If There Is No Oxygen? • After glycolysis, if there is no oxygen, fermentation will occur • Cells must regenerate more NAD+ from NADH • Yeast — form ethanol (terminal reaction produces CO2 ) • Animals — form lactic acid (ouch)

19. Biochemical Pathway Intersections Figure 6-7 • Catabolism — breakdown of complex molecules such as food; produces energy, involves oxidation • Anabolism — synthesis of complex molecules; uses energy

20. How Do Other Food Molecules Enter Metabolism? • Fat, carbohydrates and proteins enter the cellular respiration pathway at different points • The most likely point is at acetyl CoA

21. Electron Transport Chain

22. Step 4: Electron Transport & Oxidative Phosphorylation • The pathway of electrons from one carrier to another is called ____ ____ _____; • Each electron carrier passes its electrons to the next carrier (bucket brigade) • Most of the electrons to the electron transport chain are received from what cycle? • A reduced carrier becomes oxidized when it gives up its electrons (forms ATP from ADP) • Oxygen accepts electrons ELECTRON TRANSPORT CHAIN KREB’S

23. How Do Cells Harvest Energy? • Proton gradient — flow of electrons through the electron transport chain creates this gradient (ATP is made from this gradient) • Chemiosmosis— harnessing of the energy stored in the chemical gradient; some machinery in the membrane must do this process

24. Generating a Proton Gradient • Mitochondria — inner and outer membrane • Intermembrane space — space between 2 membranes • Matrix — space within the inner membrane; makes up about 2/3 of the volume; ETC is embedded in this inner membrane

25. Pumping Protons • pH & cytochromes assist w/ transport of electrons. • Gradient is produced when…..

26. ATP Synthase • Proton complex • Protons flow through these channels back into the matrix • Works like a turbine • Uses energy to make ATP

27. Key Concepts • Cellular respiration converts the chemical energy of food molecules into the chemical energy of ATP • Most cells can use glycolysis to obtain energy • ATP production from cellular respiration depends on oxidative phosphorylation