1. Chapter 9 Cellular Respiration

2. I CAN’S/ YOU MUST KNOW The difference between fermentation & cellular respiration The role of glycolysis in oxidizing glucose to two molecules of pyruvate The process that brings pyruvate from the cytosol into the mitochondria & introduces it into the citric acid cycle How the process of chemiosmosis utilizes the electrons from NADH & FADH 2 to produce ATP

3. 9.1 Catabolic pathways release energy by oxidizing organic fuels Occur when molecules are broken down Releases the molecules’ energy

4. 2 types of catabolism 1) Fermentation Partial degradation of sugars that occurs without O 2 2) Cellular Respiration Most prevalent & efficient catabolic pathway Uses O 2 as a reactant with the organic fuel Known as AEROBIC RESPIRATION CAN also use anaerobic respiration

5. Carbs, Fats, & Proteins are all broken down in cellular respiration Glucose is the primary nutrient molecule used: C 6 H 12 O 6 + 6O 6  6CO 2 + 6H 2 O + ENERGY (ATP/heat)

6. The exergonic release of energy from glucose is used to phosphorylate ADP to ATP Life processes constantly consume ATP Cellular respiration burns the organic fuels & uses the energy to regenerate ATP

7. Redox Reactions Electrons are transferred from one reactant to another Reduction = substance gains electrons & energy (reduced + charge) Oxidation = substance loses electrons & energy (oxidized) LEO GER

9. The electron donor is called the reducing agent The electron receptor is called the oxidizing agent Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds

11. During cellular respiration, the fuel (such as glucose) is oxidized, and O 2 is reduced:

12. At key steps in cellular respiration: Electrons are stripped from glucose Each electron travels with a proton (forms hydrogen) The hydrogen atoms are not transferred directly to oxygen (formula shows that) – they are passed to an electron carrier

13. Electron Carrier: Coenzyme NAD + NAD + accepts 2 electrons + the stabilizing hydrogen ion to form NADPH NADPH has been reduced & has gained energy Stored energy used later to make ATP

14. More than: C 6 H 12 O 6 + 6O 6  6CO 2 + 6H 2 O + ENERGY Cellular respiration has three stages: Glycolysis (breaks down glucose into two molecules of pyruvate) The citric acid cycle (completes the breakdown of glucose) Oxidative phosphorylation (accounts for most of the ATP synthesis)

16. 9.2 Glycolysis Occurs in cytosol The degradation of glucose begins as it is broken down into two PYRUVATE molecules The 6-Carbon glucose molecule is split into TWO 3-Carbon sugars through a long series of steps

18. 2 major phases: Energy (ATP) consuming phase Energy (ATP) producing phase

19. Energy consuming 2 ATP are used Destabilize glucose & makes it more reactive Energy producing Later in glycolysis, 4 ATP are made Results in net gain of 2 ATP 2 NADH are also made – used later

20. NET gain of 2 ATP & 2 NADH Most potential energy is still in the 2 pyruvates Pyruvates will then move to step 2 – citric acid cycle

21. 9.3 Kreb’s (Citric Acid) Cycle When O 2 is present, pyruvates enter the mitochondria Before Kreb’s begins, pyruvate is converted to acetly CoA

22. 1) Pyruvate uses a transport protein to move into the matrix of the mitochondria 2) When there, an enzyme complex removes a CO 2, strips away electrons to convert NAD+ to NADH, & adds coenzyme A to form acetyl CoA 3) Two acetyl CoA’s are produced per glucose. It now enters the citric acid cycle

24. Kreb’s (Citric Acid) 8 steps – each catalyzed by a specific enzyme The job of breaking down glucose is completed with CO 2 released as waste Each turn of the cycle requires the input of one acetyl CoA Must make 2 turns before the glucose is completely oxidized

25. One turn produces: 2CO 2, 3NADH, 1FADH 2 & 1 ATP Thus 2 turns produce: 4CO 2, 6NADH, 2FADH 2 & 2 ATP

26. At the end of the Kreb’s cycle all 6 carbons from glucose have been released as CO 2 Only 2 ATP have been produced The rest is held in the electrons in the NADH & FADH 2 Utilized in the Electron Transport Chain

28. 9.4 ETC The electron carriers will donate electrons to power ATP synthesis through OXIDATIVE PHOSPHORYLATION In the cristae of the mitochondria The ETC itself produces no ATP (comes from the products of the ETC)

30. 4 Step Process of ETC 1) ETC is embedded in the inner membrane of the mitochondria Has 3 transmembrane proteins that act as hydrogen pumps 2 carrier molecules that move electrons between hydrogen pumps 2 carrier molecules that move electrons between hydrogen pumps

31. 2) ETC is powered by electrons from NADH & FADH 2 As electrons flow, the loss of energy is used to pump protons across the inner membrane At the end of the ETC, the electrons combine with 2 hydrogen ions & Oxygen to form water Oxygen is the final electron acceptor – if none is available, the ETC STOPS!!!

32. 3) Hydrogen ions flow down their gradient through ATP synthase (channel in protein) ATP synthase harnesses proton motive force (the gradient of protons) to phosphorylate ADP The proton motive force exists because inner mit. Membrane is impermeable to hydrogen ions

34. 4) The movement of the proton motive force is called chemiosmosis Energy-coupling mechanism that uses energy from the proton gradient to drive cellular work The ETC & chemiosmosis compose OXIDATIVE PHOSPHORYLATION

35. ATP yield per molecule of glucose is between 36 & 38 ATP 32-34 comes from oxidative phosphorylation

36. ProcessNADHATPFADH 2 TOTAL ATP Glycolysis2 (3 ATP each in ETC) 4 (2 net)X8 Pyruvic acid  acetyl CoA 2XX6 Kreb’s Cycle6 (3 ATP each in ETC) 22 (2 ATP each in ETC) 24 ATP Totals:304438

38. 9.5 Fermentation allows a cell to produce ATP without Oxygen (anaerobic) Consists of glycolysis (2 net ATP) & reactions that regenerate NAD+ Oxygen not required to accept electrons

39. Types of fermentation 1) Alcohol Pyruvate is converted to ethanol Releases CO 2 & oxidizing NADH to create more NAD+ 2) Lactic acid Pyruvate is reduced by NADH (NAD+) formed Lactate is a waste product

40. Facultative anaerobes Organisms that make ATP by aerobic respiration if oxygen present Can switch to fermentation in anaerobic conditions

41. 9.6 Proteins & fats are used to generate ATP through cellular respiration Organic molecules are used in biosynthesis (the building of macromolecules) Amino acids from the hydrolysis of proteins can be incorporated into the consumer’s own proteins