Stage 3 Digestion Citric Acid Cycle Overview

Warm-up 1.Draw the entry level Rx of Glycolysis. 2.What’s the enzyme named catalyzing it? 3.Name the inhibitor of that enzyme. 4.How many ATP are made?

Pyruvate

The 3 Uses of Pyruvate it is turned into ProductAcetyl CoAEthanolLactic Acid conditionAerobicAnaerobic organismAny eukaryotic cellYeastMuscle cells organellMitochondriaCytosol purposeEndoxidation Making more NADH, ATP Regeneration of NAD for continued glycolysis

Two types of Fermentation: A. Lactic Acid - Muscles Produces no CO2 Lactic Acid is degraded in liver ≈ 3-5 hrs Does not produce post-workout muscle pain!!!

B. Alcoholic Fermentation in Yeast * Produces Ethanol and CO 2

Endoxidation Needs O 2 (aerobic) and Mitochondria to completely harvest the chemical energy left in pyruvate Pyruvate is converted to Acetyl CoA, loss of 1 st Carbon as CO 2 Enters Mitochondria

Eukaryotic cell organelle Has two membranes (like nucleus) Outer membrane believed to originate from endosymbiontic theory: mitochondria were once independent organisms: Has it’s own DNA and ribosomes Inherited from the mother

Structure of Mitochondria

Endosymbiotic Theory Endosymbiosis animation

Citric Acid Cycle (Krebs C) Central pathway for metabolizing carbs, lipids and proteins Location: Mitochondrial Matrix Has two parts: Decarboxylation and Regeneration Components are natural acids: Citric-, Malic, Oxalic-, Fumaric acid Acids in fruits/vegetables are metabolized in the citric acid cycle

Warm-up 1. Where: Glycolysis or Krebs Cycle would you find this molecule? 2. What’s its name? 3. How many ATP/NADH are made per mole glucose in the Krebs Cycle

More Warm-ups 4. What is the net yield of ATP of 1 mole of Glucose to Lactic Acid? 5. Is Lactic Acid Fermentation aerobic or anaerobic?

Stage 4 Digestion: Electron Transport Chain and ATP Synthesis

Electron Transport Chain- ETC Interconnected proteins (Cytochromes, Ferroproteins, CoQ…. ) labeled Complex I-V embedded in the inner mitochondrial membrane

A. Unloading of NADH/FADH NADH and FADH (Complex II) molecules go to Complex I – Dehydrogenase and unload the H Unloaded NAD/FAD go back to Krebs Cycle/Glycolysis H is separated into high energy e- and H+

B. Proton Pumps High energy e- passes through complexes I,II, III, IV – proton pumps that use e- energy to pump H+ into mitochondrial intermembrane space This creates a 100 x H+ difference between matrix and intermembrane space: H+ gradient: Chemiosmosis

C. The Role of Oxygen Complex IV: energy of e- has been used up Oxygen (very e-negative) absorbs e- on the matrix side – where it is neutralized by H+ gradient forming water ½ O 2 + 2e- + 2H + H 2 O Oxygen is the final electron acceptor of aerobic cellular respiration – this is why you breathe!!!

D. ATP Synthesis Harvesting energy of the H+ gradient Works like a water wheel

ATP Synthase: Complex V allows H+ gradient to rush through using energy to make ATP ADP + P+ ENERGY ATP

ADP + P ATP

animated ATP synthase

ATP Conversions 1 cytosolic NADH = 2 ATP 1 mitochondrial NADH = 3 ATP 1 mitochondrial FADH = 2 ATP

Net ATP from 1 Glucose 2 ATP (G)2 2 NADH 2 (G) = 2 FADH2 (transport)4 2NADH 2 (K prep)4 2 x 3 NADH 2 (K)18 2 x FADH 2 (K)4 2 x 1 GTP(K)2__ Total ATP34

Location?Location?Location? In which cellular compartment houses the… a.Glycolysis b.Citric Acid Cycle c.Electron Transport Chain d.Hydrogen Ion gradient e.ATPsynthase

Lipid Metabolism Cytoplasm: lipase separates Glycerol and Fatty Acids Glycerol (C3) is converted to Pyruvate (C3): yields NADH Fatty Acids are transported into Mitochondria for β-Oxidation chopped into 2 carbon molecules to make Acetyl-CoA (Krebs Cycle) Yield: 1 NADH + 1 FADH/chop ondrial matrix

Amino Acids Liver: Removal of amino group as NH 3 (ammonia) Ammonia is toxic, reacts with CO 2 to form urea, secreted as liquid waste: kidneys O NH 3 + CO 2 NH2-C-NH2 Ammonia Urea

Carbon skeleton of AA AA skeletons with 2 C → Acetyl AA skeletons with 3 C → Pyruvate AA skeletons with 4 C → Succinate Fumarate, Malate, Oxaloacetate AA skeletons with 5 C → α-Ketoglutarate