1. Breakdown of glucose to carbon dioxide and water
Cellular Respiration
Breakdown of glucose to carbon dioxide and water

2. Redox reaction
Hydrogen atoms consist of a hydrogen ion and an electron (H+ and e-)
Glucose is oxidized when the hydrogen is removed
Oxygen is reduced when it gains hydrogen and becomes water
Exergonic reaction – glucose is a high energy molecule  water and carbon dioxide are low energy molecules

4. ATP Build up of ATP = endergonic
Glucose is broken down slowly, ATP produced gradually
Maximum production of ATP = 36 – 38
39% efficiency from glucose to ATP

5. Coenzymes NAD+ (nicotinamide adenine dinucleotide)
Accepts 2 electrons and 1 hydrogen = NADH
FAD (flavin adenine dinucleotide)
Accepts 2 electrons and 2 hydrogens = FADH2

6. Making of ATP
Oxidative phosphorylation – ATP made by the redox reactions of the Electron Transport Chain (ETC and Chemiosmosis)
Accounts for 90% of the ATP generated in respiration
Substrate Level Phosphorylation – enzyme transfer a P group from a substrate molecule to ATP

7. Phases of cellular respiration
Glycolysis – outside mitochondria, anaerobic, splitting of glucose – 2 pyruvate, yield 2 ATP
Preparatory reaction – in mitochondria, pyruvate oxidized to 2 – C acetyl group, preps for citric acid cycle
Citric acid cycle – (Krebs) in matrix of mitochondria, yield 2 ATP
Electron transport chain – cristae, oxygen is final electron acceptor and forms water, result in 32 – 34 ATP

8. Glycolysis – see handout/text
Outside of mitochondria in cytoplasm
Glucose  2 pyruvate
Does not require oxygen, anaerobic

10. Energy investment
2 ATP are used to activate glucose and break down into 2 C3 molecules of G3P.

11. Energy harvesting Electrons removed (oxidation) with hydrogen ions.
NAD picks up Hydrogen and electrons = NADH
Substrate level phosphorylation – production of ATP via an enzyme passing a high energy phosphate to ADP = 4 ATP
Investment of 2 ATP minus 4 ATP = 2 net ATP

12. Prep Reaction
Pyruvate (2 C3 molecules) is converted to an acetyl group (C2) that is attached to coenzyme A (CoA)
CO2 is a product
Oxidation occurs, electrons from pyruvate are removed, NAD  NADH
Reaction occurs twice since there are 2 pyruvate per glucose molecule

13. Prep Reaction

14. Prep reaction Inputs: 2 pyruvate, 2 NAD+, 2 CoA
Outputs: 2 CO2 (Product), 2 NADH,
2 acetyl CoA

15. Citric Acid Cycle Matrix of mitochondria
C2 (acetyl CoA) joins with C4 molecule = C6 citrate molecule.
Each acetyl group is oxidized to 2 CO2 molecules = 4 CO2 total released
Cycle goes around 2 times

16. Citric Acid Cycle
Substrate Level phosphorylation - An enzyme passes a high energy phosphate to ADP = ATP
Inputs: 2 acetyl CoA, 6 NAD, 2 ADP/P, 2 FAD
Outputs: 4 CO2 (product), 6 NADH, 2 FADH2, 2 ATP

17. Prep reaction  Citric acid cycle
Cycle goes around 2 times

18. Electron Transport Chain
Electrons are carried by NADH and FADH2
Oxidation-reduction reaction starts the ETC. High energy electrons enter the chain, low energy electrons leave.
There is a series of carriers that transport the electrons, first reduced when it accepts the electrons, then oxidized when it releases them.

19. Carriers
3 protein complexes (NADH-Q reductase, cytochrome reductase and cytochrome oxidase)
2 carriers that transport electrons on ETC– coenzyme Q and cytochrome c
Cytochrome – protein that has a tightly bound heme group with a central atom of iron.

21. Oxidative phosphorylation
Hydrogen ions are pumped out of the matrix into the intermembrane space, H+ flow back through membrane due to H+ gradient = chemiosmosis
Production of ATP as a result of energy released by the ETC = 32 – 34 ATP
Production of ATP via substrate phosphorylation is 4 ATP
Total ATP = 36 – 38 ATP 39% efficiency of cellular resp.

22. ETC For each NADH that is oxidized, 3 ATP molecules are produced
For each FADH2 that is oxidized, 2 ATP are produced, (due to the fact that they follow NADH and electrons are at a lower energy level).

23. Electron transport chain
Oxygen is the final electron acceptor in the ETC
Receives last electrons and combines with the hydrogen ions to form water (product)