1. Kreb’s Cycle Step 2 in Cellular Respiration Life needs energy in order to survive and function efficiently.

2. Mitochondrion,-a “ATP Powerhouses” Produce most of energy needed by cell Some cells have 10, some have thousands(muscle cells) Remember: glycolysis and fermentation are in cytoplasm Kreb’s cycle(2) and electron transport system(3) take place in mitochondria

3. Mitochondrion,-a “ATP Powerhouses” Produce most of energy needed by cell Some cells have 10, some have thousands(muscle cells) Remember: glycolysis and fermentation are in cytoplasm Kreb’s cycle(2) and electron transport system(3) take place in mitochondria

4. Mitochondrion Structure Two membranes Outer Inner Lipid Bilayer Inner membrane Many enzymes Folds into matrix(interior space) http://ebiomedia.com/gall/cellimgs/mito_320.jpg Outer membrane Inner membrane matrix

5. Kreb’s Cycle Named after Sir Hans Kreb Oxford University in England a.k.a “citric acid cycle” Citrate or citric acid is produced in this cycle Purpose: Take pyruvate from glycolysis and break down completely into carbon dioxide. Pyruvate Carbon Dioxide Kreb’s Cycle

6. Prep 1 Preparing for Kreb’s cycle Pyruvate is sent from cytoplasm into mitochondria CCC

7. Prep 2: Enzymes break off a molecule of CO2 from pyruvate Now acetate (2 carbon acid) Also known as aceitic acid NADH+ becomes NADH CCC NAD+ Pyruvate

8. Prep 2: Enzymes break off a molecule of CO2 from pyruvate Now acetate (2 carbon acid) Also known as aceitic acid NAD+ becomes NADH CCC NAD+ NADH Acetate Carbon dioxide

9. Prep 3: CoA(Coenzyme A) binds to acetate A carrier molecule Carries acetate to the Kreb’s cycle CC Acetate CoA

10. Prep 3: CoA(Coenzyme A) binds to acetate A carrier molecule Carries acetate to the Kreb’s cycle Overall: Produces 1 NADH and 1 CO 2 CC Acetate CoA Kreb’s Cycle

11. Kreb’s Cycle: Step 1 Acetate Group of Acetyl/CoA combines with oxaloacetate(4-carbon) Forms a 6 carbon acid “citrate” Where it gets its nickname “citric acid cycle” CC CoA CCCC oxaloacetate Acetyl/CoA complex

12. Kreb’s Cycle: Step 1 Acetate Group of Acetyl/CoA combines with oxaloacetate(4-carbon) Forms a 6 carbon acid “citrate” Where it gets its nickname “citric acid cycle” CCCCCC citrate

13. Kreb’s Cycle: Step 2 Two carbon atoms are oxidized to form 2 more CO2 NAD converted to NADH Produces a 4 carbon acid CCCCCC citrate NAD+

14. Kreb’s Cycle: Step 2 Two carbon atoms are oxidized to form 2 more CO2 NAD converted to NADH Produces a 4 carbon acid CC CCCC 4-carbon acid NAD+ NADH 2 carbon dioxide

15. Kreb’s Cycle: Step 3 4 carbon acid is rearranged and oxidized to form original oxaloacetate Produce 3 NADH Produce 1 FADH2 Produce 1 ATP Produce 2 CO 2 NOTE: One glucose molecule makes two pyruvate, so two Kreb’s cycles run from one glucose moleculeNOTE CCCC 4-carbon acid

16. Kreb’s Cycle: Step 3 4 carbon acid is rearranged and oxidized to form original oxaloacetate Produce 3 NADH Produce 1 FADH2 Produce 1 ATP Produce 2 CO 2 NOTE: One glucose molecule makes two pyruvate, so two Kreb’s cycles run from one glucose moleculeNOTE CCCC oxaloacetate 1 NADH 1 FADH2 1 ATP