Link Reaction and the Kreb’s Cycle

Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Krebs cycle

Structure of Acetyl Coenzyme A CoA Serves to chemically activate acetyl group for transfer Coenzyme A is a good leaving group (again, facilitates transfer of acetyl group) You can see from the structure below why we abbreviate this as CoA!

Inputs Outputs S—CoA 2 ATP C O CH3 2 Acetyl CoA 6 NADH O C COO Fig. 9-UN6 Inputs Outputs S—CoA 2 ATP C O CH3 2 Acetyl CoA 6 NADH O C COO Citric acid cycle CH2 2 FADH2 COO 2 Oxaloacetate

Figure 9.11 A closer look at the Krebs cycle (Layer 1)

Figure 9.11 A closer look at the Krebs cycle (Layer 2)

Figure 9.11 A closer look at the Krebs cycle (Layer 3)

Figure 9.11 A closer look at the Krebs cycle (Layer 4)

Figure 9.12 A summary of the Krebs cycle

Link to Krebs cycle animation (Smith College) Link to Krebs cycle Campbell’s

Link to Summary of Aerobic Respiration

Oxidative Phosphorylation Electron Transport and Chemiosmosis

Fig. 9-13 NADH 50 2 e– NAD+ FADH2 2 e– FAD Multiprotein complexes  40 FMN FAD  Fe•S Fe•S Q  Cyt b Fe•S 30 Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c Cyt a Cyt a3 20 e– 10 2 (from NADH or FADH2) 2 H+ + 1/2 O2 H2O

Electron transport chain 2 Chemiosmosis Fig. 9-16 H+ H+ H+ H+ Protein complex of electron carriers Cyt c V Q   ATP synthase  2 H+ + 1/2O2 H2O FADH2 FAD NADH NAD+ ADP + P ATP i (carrying electrons from food) H+ 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation

INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob ADP Fig. 9-14 INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob ADP + P ATP i MITOCHONDRIAL MATRIX

Link to electron transport Link to Summas Link to ATP synthease Roto animation Link to McGraw-Hill Oxidative Phosphorylation Link to Harvard

Cyanide poisoning Link to Summas Cyanide poisoning Link to what happens when you run out of oxygen Link to Summas

Fig. 9-17 Citric acid cycle CYTOSOL Electron shuttles span membrane MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Glycolysis Oxidative phosphorylation: electron transport and chemiosmosis 2 Pyruvate 2 Acetyl CoA Citric acid cycle Glucose + 2 ATP + 2 ATP + about 32 or 34 ATP About 36 or 38 ATP Maximum per glucose:

Figure 9.19 The catabolism of various food molecules

Metabolism of Proteins

Beta Oxidation of Fatty Acids Triacyglyercols are broken down into 2 Carbon Acetyl-CoA molecules and fed into Krebs cycle. Link to Beta Oxidation (Campbells) Link to 2 C beta oxidation Note: A 16 carbon fatty acid would be broken down into 16÷2 = 8 CoA segments. Excellent overview of Beta oxidation

27) You are a doctor and a male patient comes to you with the following symptoms: 1) Complains of low energy (easily fatigued) 2) Blood tests reveal higher than normal levels of lactate. 3) Tests reveal that the patient’s mitochondria can only utilize fatty acids and amino acids for respiration.   Of the following, which is the best explanation of the patient’s condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells contain a chemical that inhibits oxygen use in his mitochondria. C) His cells lack the enzyme in glycolysis that forms pyruvate. D) His cells have a defective electron transport chain, so glucose goes to lactate instead of acetyl CoA.

Figure 9.20 The control of cellular respiration