Aerobic cellular respiration

1. Aerobic Cellular Respiration By: Meghan Taylor

2. Agenda Curriculum Expectations Overview of cellular respiration Glycolysis Pyruvate Oxidation Kreb’s Cycle Chemiosmosis and Electron Transport Chain Activity

3. Curriculum Expectations C2.1: use appropriate terminology related to metabolism, including, but not limited to: energy carriers, glycolysis, Krebs cycle, electron transport chain, ATP synthase, oxidative phosphorylation, chemiosmosis, proton pump, photolysis, Calvin cycle, light and dark reactions, and cyclic and noncyclic phosphorylation C3.1explain the chemical changes and energy conversions associated with the processes of aerobic and anaerobic cellular respiration c3.3 use the laws of thermodynamics to explain energy transfer in the cell during the processes of cellular respiration and photosynthesis c3.4 describe, compare, and illustrate (e.g., using flow charts) the matter and energy transformations that occur during the processes of cellular respiration (aerobic and anaerobic) and photosynthesis, including the roles of oxygen and organelles such as mitochondria and chloroplasts

4. Aerobic Cellular Respiration Occurs in the presence of oxygen An exothermic reaction (∆G= - 2870 kJ/ mol ) The cell only captures 34% of the available free energy in the form of ATP 3 goals: To break the bonds between the 6-C atoms of glucose, resulting in 6 carbon dioxide molecules To move hydrogen atom electrons from glucose to oxygen , forming 6 water molecules To trap as much of the free energy released in the process as possible in the form of ATP .

5. ATP: Adenosine Triphosphate Contains a nitrogenous base (adenine), a ribose sugar and 3 phosphate group High energy bond between the 2 nd and 3 rd phosphate group When that bond is broken, an abundance of energy is released

6. Energy Transfer 2 ways in which available free energy is captured into the form of ATP Substrate-Level Phosphorylation ATP is formed directly in an enzyme-catalyzed reaction.

7. Energy Transfer NAD+ to NADH: NAD+ removes 2 hydrogen atoms (2 protons, 2 electrons) from glucose forming NADH using a dehydrogenase enzyme FAD to FADH 2: FAD is reduced by 2 hydrogen atoms from glucose 2. Oxidative Phosphorylation ATP is formed indirectly through a series of enzyme-catalyzed redox reactions involving oxygen as the final electron acceptor. LEO the lion goes GER Lose electrons, oxidization Gain electrons, reduction

8. Glucose: 6- carbon monosaccharide Primary source of energy for plants and animals

9. Glycolysis 10 step process that occurs in the cytoplasm under anaerobic conditions A process that evolved in prokaryotes prior to the emergence of organelles, notably the mitochondria 1. Glucose is phosphorylated to G6P ( Investment phase ) 2. Glucose is rearranged to F6P 3. Glucose is phosphorylated to F1,6-BP ( investment phase )

10. Glycolysis (cont’d) 4&5 . F 1, 6-BP is split into DHAP and G3P, then DHAP is converted into G3P, resulting in two G3P m olecules 6. Two G3P are converted to two BPG. Hydrogen atoms reduce NAD+ to NADH . 7. BPG is converted to 3PG . A high energy phosphate group on BPG phosphorylates ADP to AT 8 . 3PG is rearranged to 2PG

11. Glycolysis 9. 2PG is converted to PEP by removal of a water molecule 10. PEP is converted to pyruvate . A high energy phosphate group on PEP phosphorylates ADP to ATP Invested 2 ATP Gained 2 NADH 4 ATP Net: 2 NADH and 2 ATP

12. Glycolysis Links: http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__ how_glycolysis_works.html Youtube videos: http:// www.youtube.com/watch?v=evYmyHgj550 http:// www.youtube.com/watch?v=EfGlznwfu9U

13. Mitochondria The power house of the cell, specialized organelles that generate ATP Only eukaryotic cells contain mitochondria Double membrane, inner membrane is highly specialized

14. Pyruvate Oxidation Carboxyl group is removed as CO 2 (by pyruvate decarboxylase) Pyruvate is oxidized while NAD+ is reduced CoenzymeA (CoA) is attached to the acetyl group . Gained: 1 NADH (X2 for each pyruvate)

15. Kreb’s Cycle Gained: 1 ATP 3 NADH 1 FADH2 (X2 for each acetyl-CoA)

16. Kreb’s Cycle Links: http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_. html Student Project: http:// www.youtube.com/watch?v=aMBIs_Iw0kE&list=PLBiiS3G1bbMpPr8SBg9tcwaTxoaVBb5WW

17. From here.. By the end of the Kreb’s cycle the original glucose molecule has been consumed as the carbon atoms exited as waste in the form of CO 2 We have created 4 ATP molecules via substrate level phosphorylation, 10 NADH and 2 FADH 2

18. Electron Transport and Chemiosmosis NADH and FADH2 eventually transfer the hydrogen atom electrons they carry to a series of proteins in the inner mitochondrial membrane, called the ETC Each component is alternately reduced from the component before it and oxidized by the component after it. Electrons from NADH and FADH2 are shuttled from one component to the next like a baton in a relay race. Oxygen is one of the most electronegative components, which is needed to oxidize the last component of the ETC

19. ETC Components of ETC are arranged in order of increasing electronegativity ( The ability of an atom in a molecule to attract a shared electron pair to itself ) Ubiquinone and cytochrome C are mobile electron carriers that shuttle the electrons from one complex to the next. Many folds of the inner membrane increase surface area and allow many copies of the ETC

20. ETC cont’d http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__electron_transport_system_and_atp_synthesis__quiz_1_. html

21. ETC cont’d NADH passes its electrons on to the first protein complex , and FADH 2 transfers its electrons to Q Therefore FADH 2 pumps 2 protons into the inter membrane space while NADH pumps 3. Cytosolic NADH created in glycolysis cannot pass through the inner membrane into the matrix Glycerol-phosphate shuttle oxidizes NADH to reduce FAD in the matrix into FADH 2 so that it can be used.

22. Chemiosmosis An electrochemical gradient is created with the H+ ions built up in the inter membrane space, storing free energy. The inner mitochondrial membrane is impermeable to protons, forcing them to pass through special proton channels associated with ATP synthase As protons move through the ATP synthase complex, the free energy of the gradient is reduced This causes the synthesis of ATP from ADP and inorganic phosphate in the matrix

23. What if there was no O2? Without oxygen, we wouldn’t be able to free up the last protein (cytochrome oxidase) and the chain would be clogged with stationary electrons. Then H+ ions would not be pumped into the inter membrane space to create the electrochemical gradient.

24. The Big Picture

25. How many ATP molecules?

26. ETC tools: Kinesthetic learners: http:// www.scienceprofonline.com/metabolism/electron-transport-chain-classroom-activity.html

27. How many ATP did you create if…. Under normal conditions? You were in anaerobic conditions? Through just NADH?