Energy Releasing Pathways (Cellular Respiration) I. Introduction A. History 1. Antoine Lavoisier in the 1700’s can make wine without living organisms. 2. Wohler and von Leibig supported this idea, but Schwann showed juice would not ferment without yeast. 3. In 1860 Pasteur proved ethanol amount proportional to the amount of yeast present.

4. In 1897 the Buchner brothers outlined the steps of glycolysis key to fermentation. 5. In the early 1900’s Szent-Györgyi designed Citric Acid Cycle, failed to show relationship to fermentation. 6. Krebs in 1938 linked glycolysis to citric Acid Cycle via enzyme CoA. Kreb’s Cycle

Cellular Respiration or releasing energy from glucose with the use of O2. Figure 7.1

B. Overview Figure 7.2

II. Aerobic Respiration Pathways A. Glycolysis 1. Where located? Cytoplasm of all cells Figure 4.7 Figure 4.8

2. Steps a. Investment b. Splitting Three components: & c. Harvest Kinases b. Splitting Three components: Aldolase & c. Harvest Dehydrogenase Figure 7.3

a. Investment b. Splitting i. Enzyme (named Kinase) attaches a P from ATP to glucose after facilitatedly diffusing into the cell This prevents glucose from diffusing back out of cell. ii. Attach another P from second ATP to glucose This generates a balanced molecule with a P at either end. b. Splitting i. Enzyme (named Aldolase) cuts molecule into two G3P’s ii. Liberates H+ and NAD+ steals the electron from H+ to form NADH (This releases two H+ electrons) iii. The hole left by the leaving of each H+ is backfilled by a Pi (inorganic phosphate) This step balances the G3P with a P on either end. This happens twice or once for each G3P. How many NADH are formed per glucose?

c. Harvest i. Enzyme (named Dehydrogenase) directly transfers a P from G3P to ADP to make ATP via SLP How many times does this happen to make how many ATP’ s? ii. Makes two molecules of pyruvate Figure 7.4 Substrate-Level Phosphorylation (SLP) or Direct Phosphorylation (ATP synthesis)

The next two outcomes only happen if oxygen is present in the cell. a. The 2ATP’s are used by the cell. The next two outcomes only happen if oxygen is present in the cell. b. The NADH are transported to the inner mitochondria membrane (imm.)and used in the electron transport chain. c. The 2pyruvic acids are each combined to a Co-enzyme A (CoA) to go to the mitochondria and the Kreb’s cycle. 3. Outcomes

B. Transport to Mitochondria 1. Where located? Figure 7.5

2. Steps Taxi anyone? a. Splitting b. Adding Acetic acid Figure 7.6 a. Splitting = Enzyme (Dehydrogenase) splits off a CO2 from a pyruvate which liberates electrons from Hydrogen which are given to NAD+ to form NADH and to make a 2C acetyl group (acetic acid). b. Adding = Combine the acetyl group (acetic acid) to Co-enzyme A (CoA) to be transported to the mitochondria.

The next three outcomes only happen if oxygen is present in the cell. a. The NADH transported to the mitochondria and used in the electron transport chain. The next three outcomes only happen if oxygen is present in the cell. b. The 2pyruvic acids are each combined to Co enzyme A (CoA) to go to the mitochondria and the Kreb’s cycle. c. CO2 diffuses into cytosol and lost.

C. Kreb’s Cycle 1. Where located? Six step Kreb’s cycle  mitochondrial matrix Figure 7.6

2. Steps An enzyme (Citrate Synthase) adds the acetic acid to oxaloacetic acid to make citric acid. The cycle is divided into the destroying and rearranging side. Acetic acid Oxaloacetic acid Citric acid Figure 7.7

a. Destroying b. Rearranging i. Enzyme (Citrate Synthase) combines the acetic group with oxaloacetic acid to begin cycle. ii. Enzymes (Dehydrogenase) splits out 2CO2 and liberates 2H+ to 2NAD+ to make NADH How many CO2 are liberated per acetic acid? Per glucose? iii. As H+’s are removed then a Pi jumps on only to be removed to form ATP (Direct or Substrate Level Phosphorylation). b. Rearranging i. Enzymes (Dehydrogenase) reshape the molecule to liberate more H+’s to rebuild oxaloacetic acid. ii. Liberates H+ and NAD+ or FAD+ steals the electrons to make NADH or FADH2. This happens twice or once for each acetic group.

3. Outcomes c. The NADH and FADH2 transported to the mitochondria and used in the electron transport chain. a. The ATP’s are used by the cell. b. CO2 diffuses into cytosol and lost as waste.

D. Electron Transport Chain 1. Where located? Inner Mitochondrial Membrane (imm.) Protein based reactions  oxidation/reduction (cytochromes) reactions release energy to make ATP via ATP synthase. Figure 7.7

2. Steps  Divided into build-up and Harvest Figure 7.9

a. Build Up i. NADH and FADH2 drop the electrons from H+ to a series of re-dox proteins called cytochromes. ii. As electrons move down the chain they lose energy which is used to move the H+ proton across the Imm. to establish potential energy. b. Harvest i. The electrons are eventually passed to an awaiting Oxygen atom. ii. The H+ proton moves back across the Imm. through ATP synthase and to the waiting O2 to form water. iii. Conversion of energy (Potential to Kinetic) is used to form ATP via ATP Synthase.

3. Outcomes c. Water moved out or used. b. NAD+ and FAD+ sent back to be reused. a. ATP used by the cell.

E. Summary of Aerobic Respiration Figure 7.8

III. Anaerobic Respiration Pathways A. Fermentation Fermentation uses only glycolysis for ATP production. Which kingdoms perform this strategy ?

B. Lactic Acid Shuttle Which kingdoms perform this strategy ?

IV. Versatility A. Pathways B. Problems & Issues What does this picture explain about your diet? Figure 7.11