1. Ch. 9 Cellular Respiration

2. Harvesting chemical energy Living is lots of work Polymerization, Growth, highly organized, and movement all require energy Energy enters Earth’s ecosystems as sunlight Harvesting of energy requires a series of metabolic steps AEROBIC CELLULAR RESPIRATION Glycolysis Kreb’s cycle Electron transport chain

3. Organic compounds Energy stored in chemical bonds (position) Enzymes help regulate this metabolism Organic macromolecules are rich in potential energy and are broken down to simpler compounds with less energy. Breaking of bonds allows work to be done. Organic + oxygen  carbon + water + energy compounds dioxide

5. Exergonic reaction Organic + oxygen  carbon + water + energy compounds dioxide C 6 H 12 O 6 + 6 O 2  6 CO 2 + 6 H 2 O + energy (ATP + heat)  G = - 686 kcal

6. Possible pathways Complete, aerobic cellular respiration Complete oxidation of carbohydrates using Glycolysis Kreb’s cycle and Electron transport chain REQUIRES OXYGEN Incomplete/ partial oxidation Gylcolysis only Glycolysis + Lactic acid fermentation Glycolysis + Alcoholic fermentation

8. Redox reactions Movement of e - is what is used to store and release energy in bonds of organic cpds. Redox reactions – “oxidation-reduction reactions” transfer an e- from one reactant to another Reduction Addition/receipt of e-, more negative Oxidation Loss of e- (often to O), more positive

10. Falling electrons The step wise fall of electrons from organic compounds rich in bonds, to simpler compounds increases the entropy of the system. Electrons are shuttled through a series of carriers (membrane proteins) that allows for release of energy to be in small (usable) increments. Electron transport chains

12. Aerobic cellular respiration Requires oxygen ( for e- acceptor at end of ETC) 3 parts Glycolysis ( splitting of sugar molecules ) Some substrate level phosphorylation of ATP Kreb’s cycle ( transfer of e- to NADH, FADH) Some substrate level phosphorylation of ATP ETC ( generates ATP using ETC) Much oxidative phosphorylation of ATP Occurs in eukaryotic cells – need mitochondrion (for Krebs and ETC) and oxygen supply for (ETC)

15. Glycolysis Glyco = sugar, glucose Lysis = to split or break “sugar splitting” Cytoplasm ALL CELLS ! Doesn’t require mitochondrion or O 2 1 glucose = 2 ATP and 2 NADH 2 ATP are net ( 4 generated – 2 invested ) Know steps on pgs. 168-169….green boxes Note color coding used in chapter – green = glycolysis, salmon = Kreb’s and purple = ETC

17. Summary of Steps 1.Spend 1 ATP Add P to glucose 2. Glucose converted to isomer (fructose) by an enzyme 3. Spend 2 nd ATP add 2 nd P to fructose now in debt ( 2ATP) Molecule very unstable (primed)

18. Summary of Steps 4. 6 C sugar “cleaved” into 2 – 3C sugars They are isomers 5. An enzyme called ‘isomerase’ converts both isomers into glyceraldehyde (PGAL) From now on all steps are X2 PGAL

19. Summary of Steps 6. Enzyme adds an inorganic phosphate, sugar give e- and H+ to NAD making NADH…remember x2 7. MAKE ATP (X2) now out of debt, organic acid 8. Relocate P ( on both molecules)

20. Summary of Steps 9. Generates water and creates double bond…. P bond now unstable 10. P leaves – adds to ADP generates more ATP (2more) now have 2 net ATP. Glucose is now split into 2 – 3 C molecules PYRUVATE 2 NADH can go to ETC and make ATP using oxidative phosphorylation

21. Krebs Cycle – aka Tricarboxylic Acid Cycle (TCA) and Citric Acid Cycle Sir Hans Krebs: 1900-1981, 1953 Nobel Prize, 1958 knighted 3 C pyruvate at end of glycolysis Not soluble in mitochondrial membrane Loses C (CO 2 ) becomes acetyl Creates a NADH ( stores some energy ) Bonds to coenzyme for transport – now Acetyl CoA Crosses mitochondrial membrane Bonds to 4C oxaloacetate to make 6C citrate or citric acid Series of steps to lose C ( makes CO 2 ) and Store energy as NADH and FADH and ATP Regenerates the oxaloacetic acid…. “cycle”

23. Electron Transport Chain Collection of molecules embedded in the inner mitochondrial membrane Folding increases surface area ( # of reactions) Most compounds are proteins (some pigments) cytochrome c used to trace DNA lineage Function as enzymes directing the flow of reactions that move e- (alternate between oxidized and reduced state) NADH and FADH2 are from Krebs and glycolysis NADH and FADH2 release H to these reactions H is split into H+ and e- The e- move through the carriers to the biggest e- acceptor (moving down hill – releasing potential energy and increasing entropy) The H+ accumulate in space btwn membranes

24. ETC continued As the e- get to the last acceptor they have released all the energy they were carrying from C-C bonds in glycolysis and Krebs The H+ can not accumulate indefinitely btwn membranes (high acidity) H+ flows through protein pump called ATP synthase toward e- and their acceptor (OXYGEN) This creates water and also Is used to generated energy to add P to ADP ATP is generated using oxidative phosphorylation