1. The Big Picture

2. The Circle of Life... Photoautotophs: organisms that can build all the organic compounds required for life from simple ________________ materials, using _____________ in the process. Green plants and photosynthetic microorganisms Heterotrophs: organisms that feed on other organisms to obtain _____________ energy. Animals, fungi, most protists and bacteria Chemoautotrophs: organisms that can build all the organic compounds required for life from simple _______________ materials without using _____________ energy. Some archaebacteria Likely the first organisms on Earth

3. Glucose With the exception of chemoautotrophs, all organisms use glucose. Through a series of enzyme-controlled redox reactions, covalent bonds broken and rearranged into more stable configurations. Therefore, a _______________ of energy.

4. Aerobic Cellular Respiration glucose is oxidized to carbon dioxide and oxygen is reduced to water. Takes about 20 reactions. Aerobic Cellular Respiration: oxygen is used.

5. Oxidation of Glucose Contains number of C-h bonds. Oxygen oxidizes these bonds in two ways C-H bonds relatively nonpolar (0.4), therefore, electron pairs are shared almost ____________. 12 hydrogen atoms break away from glucose and attach to six oxygen atoms from the six oxygen (O2) molecules  six H2O molecules.

6. Called oxidation: hydrogen atoms carry electrons away from the carbon atoms. When H forms covalent bonds with oxygen, shared electron pairs occupy positions closer to the oxygen nuclei than they did when they were part of glucose. H moves from EN C atoms in glucose to highly EN oxygen atooms  lose potential energy. Decrease in potential energy + increase in entropy  decrease in free energy (of the system)  overall exergonic process.

7. What about the Carbon Dioxide? Remaining oxygen atoms must be attached to carbon atoms, forming the six carbon dioxide molecules on the product side of the overall equation. C-O bonds are polar, therefore, oxidation reaction. More stable configuration  release of free energy.

8. Aerobic Oxidation of Glucose Overall: involves the movement of valence electrons from a higher free energy state in glucose to a lower free energy state in carbon dioxide and water. Decrease in potential energy, increase in entropy.

10. Combustion of Glucose When glucose is burned in test tube, carbon dioxide, water, and heat + light (flame) are formed. It would not be good for the glucose in living cells to combust and give off energy as heat. Cells have evolved methods to trap energy (about 34%). Positions of electrons in certain molecules (like ATP) moved to higher free energy states  become readily available source of free energy to power _______________processes.

12. Glucose and Activation Energy If reaction occurred every time glucose and oxygen came into contact, ____________________________. All living things would be converted to ________________, ___________________, and ___________________. Amount of ________________________ needed for combustion of glucose is relatively high. Therefore, ______________ needed!

13. Enzymes and Respiration Specific enzymes catalyze every step in the aerobic respriration process. Lower _________________________ and allow reactions to occur at a rate that is __________________ with the needs of the _____________. Available free energy transferred to a number of energy-carrier molecules, including _______.

14. Spontaneous Human Combustion? What do you think? http://www.youtube.com/watch?v=yYyBPdxS2e8&feature=related

15. Other ways of Obtaining Energy Obligate Aerobes: have to use aerobic respiration: obtain energy by oxidizing organic substances using oxygen. _______________, ___________________, ______________, __________ Obligate Anaerobes: cannot live in the presence of oxygen and obtain energy by oxidizing inorganic substances (NO2, SO4, CO2, and Fe 3+ ) Mostly bacteria Examples: Clostridium tetani (tetanus), Clostridium perfringens (gas gangrene). Facultative Anaerobes: obtain energy by oxidizing inorganic substances with or without oxygen mostly bacteria Examples: Vibrio cholerae (colera) and Salmonella enteritidis (food poisoning).

16. Summary

17. Classwork/Homework Pg. 93, #1-5

18. Cellular Respiration – Introduction to the Details There are many steps to cellular respiration, and it may seem overwhelming at times. Keep in mind the overall equation: _______________________________________________ There are three overall goals of the process 1) To break 6 C-C bonds in glucose to make 6 CO2 2) To move hydrogen atom electrons from glucose to oxygen, forming 6 H2O. 3) To trap as much of the free energy released in the process as possible in the form of _____.

19. Parts of the Mitochondria

20. Cell Respiration can be divided into 4 Parts: 1) Glycolysis 2) Oxidation of Pyruvate / Transition Reaction 3) The Krebs Cycle 4) The Electron Transport Chain and Chemiosmotic Phosphorylation

21. 1) Glycolysis 10-step process occurring in the cytoplasm. Glucose  pyruvate Uses substrate-level phosphorylation. ATP is formed

22. 2) Pyruvate Oxidation 1-step process occuring in the mitochondrial matrix Pyruvate  acetyl CoA Releases NADH

23. 3) The Krebs Cycle Also called the tricarboxylic acid cycle, TCA or the citric acid cycle. 8-step cylical process occurring in the mitochondrial matrix

24. 4) Electron Transport and Chemiosmosis (oxidative phosphorylation) Multistep process occuring in the inner mitochondrial membrane.

25. Ultimate Goal for all of these steps? To ________________ energy from nutrient molecules and store it in a form that the ____________ can use for its many and varied _____________-requiring activities. The primary energy transfer is from ______________ to __________________.

26. Energy Transfer Cell wants to capture as much of the available free energy as possible in the form of ___________. Two energy-transfer mechanisms Substrate-level phosphorylation Oxidative phosphorylation

27. Substrate-Level Phosphorylation ATP formed directly in an enzyme-catalyzed reaction. Phosphate-containing compound transfers a phosphate group directly to ADP. ADP + Pi + energy  ATP ∆G= 31 kJ/mol For each glucose molecule processed 4 ATP generated this way in glycolysis 2 ATP generated this way in the Krebs cycle

29. Oxidative Phosphorylation APT formed indirectly Involves a series of redox reactions, with oxygen being the final electron acceptor. Much more complex than substrate-level phosphorylation!

30. Steps in Oxidative Phosphorylation FORMING NADH 1) Coenzyme Nicotinamide adenine dinucleotide, NAD+: removes 2 hydrogen atoms (2P + 2e-) from portion of original glucose molecule. 2) Dehydrogenase enzyme: 2e- and 1P attach to NAD+  _______. Remaining proton dissolves into solution as _______. NAD+  __________________ form NADH  __________________ form

32. FORMING FADH2 1) Coenzyme FAD is reduced by two hydrogen atoms from a portion of the original glucose molecule. FAD + 2e- + 2P  FADH2.

34. So, what’s the point of forming NADH and FADH 2 ? All reduced coenzymes formed within first three statges (glycolysis, pyruvate oxidation, Krebs Cycle) The reductions of NAD+ to NADH and FAD to FADH2 are energy-harvesting reactions Act as mobile energy carriers within the cell Will eventually transfer most of free energy to ATP during electron transport & chemiosmosis.

35. Anaerobic Respiration (no oxygen required, cytoplasm) 1.Glycolysis (substrate level) Glucose  4 ATP (Net 2 ATP) 2 ATP2 NADH 2 Pyruvate Aerobic Respiration (oxygen required, mitochondria) 2. Oxidation of Pyruvate 2 Pyruvate  2 CO 2 2 NADH 2 Acetyl CoA 3.Krebs Cycle (substrate level) 2 Acetyl CoA  4 CO 2 2 ATP 6 NADH 2 FADH 2 4.Electron Transport Chain (chemiosmotic) 10 NADH  32 ATP 2 FADH 2 6 H 2 O 6 O 2 Total: 36 ATP produced

36. Ideas for Assignment?