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

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

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

Mitochondrion Structure Two membranes Outer Inner Lipid Bilayer Inner membrane Many enzymes Folds into matrix(interior space) Outer membrane Inner membrane matrix

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

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

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

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

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

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

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

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

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+

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

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

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