Cellular Respiration Part 3 Krebs Cycle – Pages 96 to 97

Chemically Grooming Pyruvate 3 steps to Krebs Cycle Carbon atom is removed (3C to 2C) and released as CO2 2C compound is oxidized while NAD+ is reduced to NADH Coenzyme A joins with 2C to form acetyl co-A

CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Pyruvate Fig. 9-10 CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the citric acid cycle Pyruvate Coenzyme A CO2 Transport protein

Krebs Cycle (Citric Acid Cycle) Called the Citric Acid Cycle because Citric Acid (citrate) is the 1st molecule formed in the cycle Called the Krebs Cycle after Hans Krebs – the researcher who discovered it Occurs in the matrix of the mitochondria Involves 2 electron carriers – NADH and FADH2 The cycle oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn

Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 Fig. 9-11 Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 CO2 Figure 9.11 An overview of the citric acid cycle FADH2 3 NAD+ FAD 3 NADH + 3 H+ ADP + P i ATP

Summary of Krebs Cycle 2C of acetyl Co-A joins with 4C of OAA to form 6C citrate; Co-A is recycle Thru a series of energy extracting reactions 2CO2, 3NADH, 1FADH2 + 1 ATP are produced per turn Remaining 4C molecule is rearranged to form OAA

Products for 1 glucose including grooming: Fig. 9-12-8 Acetyl CoA Products for 1 glucose including grooming: 8 NADH 2 FADH2 2 ATP 6 CO2 Products for 1 turn including grooming: 4 NADH 1 FADH2 1 ATP 3 CO2 CoA—SH NADH +H+ 1 H2O NAD+ 8 Oxaloacetate 2 Malate Citrate Isocitrate NAD+ Citric acid cycle NADH 3 7 + H+ H2O CO2 Fumarate CoA—SH -Keto- glutarate Figure 9.12 A closer look at the citric acid cycle 4 6 CoA—SH FADH2 5 CO2 NAD+ FAD Succinate P NADH i GTP GDP Succinyl CoA + H+ ADP ATP