PAUL VI CATHOLIC HIGH SCHOOL CELL RESPIRATION Chapter 9 CP Biology PAUL VI CATHOLIC HIGH SCHOOL

CELL RESPIRATION Breathing and Respiration are not the same. Breathing allows the exchange of O2 and CO2 between an organism and its environment. In cellular respiration Mitochondria use O2 and produces CO2 as waste. CO2 O2 Bloodstream Muscle cells carrying out Cellular Respiration Breathing Glucose + O2 CO2 +H2O +ATP Lungs

CELL RESPIRATION CO2 H2O Glucose O2 ATP ECOSYSTEM Sunlight energy Photosynthesis in chloroplasts Cellular respiration in mitochondria (for cellular work) Heat energy + Photosynthesis and cellular respiration provide energy for life Cellular respiration makes ATP and consumes O2 during the oxidation of glucose to CO2 and H2O Photosynthesis uses solar energy to produce glucose and O2 from CO2 and H2O

Multi-step process not a single reaction Cellular respiration breaks down glucose molecules and banks their energy in ATP -”Glucose” used in examples for convenience. Other organic molecules are also used as “food” Glucose releases chemical bond energy, which the cell stores in the chemical bonds of ATP Multi-step process not a single reaction C6H12O6 CO2 6 H2O ATPs Glucose Oxygen gas Carbon dioxide Water Energy O2 + Figure 6.3

CELL RESPIRATION Electrons lose potential energy during their transfer from organic compounds to oxygen When glucose is converted to carbon dioxide it loses hydrogen atoms, which are added to oxygen, producing water C6H12O6 6 O2 6 CO2 6 H2O Loss of hydrogen atoms (oxidation) Gain of hydrogen atoms (reduction) Energy (ATP) Glucose +

CELL RESPIRATION GLUCOSE CATABOLISM STAGE I: GLYCOLYSIS STAGE II: PYRUVATE OXIDATION STAGE III: KREBS CYCLE STAGE IV: ELECTRON TRANSPORT

CELL RESPIRATION Cellular Respiration Overview Video

Glycolysis harvests chemical energy by oxidizing glucose to pyruvate Glycolysis harvests chemical energy by oxidizing glucose to pyruvate ATP is used to prime a glucose molecule Which is split into two molecules of pyruvate NAD+ NADH H+ Glucose 2 Pyruvate ATP 2 P 2 ADP + Figure 6.7A

CELL RESPIRATION

CELL RESPIRATION GLYCOLYSIS: 1. Glucose Priming: occurs in the cytoplasm of every living cell 1. Glucose Priming: changes glucose into a molecule that can be “cleaved”. Requires 2 molecules of ATP Phosphofructokinase: commits glucose to glycolysis

PREPARATORY PHASE (energy investment) In the first phase of glycolysis ATP is used to energize a glucose molecule, which is then split in two  Steps      –   A fuel molecule is energized, using ATP. 1 3 Glucose PREPARATORY PHASE (energy investment) ATP Step 1 ADP P Glucose-6-phosphate 2 P Fructose-6-phosphate ATP 3 ADP P P Fructose-1,6-diphosphate  Step      A six-carbon intermediate splits into two three-carbon intermediates. 4 4 Figure 6.7C

CELL RESPIRATION 2. Splitting & Rearrangement: Six carbon compound splits to (2) 3 “C” compounds. Fructose 1,6, Diphosphate into (2) G3P (Glyceraldehyde-3-Phosphate) “Substrate Level Phosphorylation” Making ATP (4 molecules/glucose)

Organic molecule (substrate) In Glycolysis ATP is produced by substrate-level phosphorylation - a phosphate group is transferred from an organic molecule to ADP using an enzyme Enzyme Adenosine Organic molecule (substrate) ADP ATP P Figure 6.7B

In the second phase of glycolysis ATP, NADH, and pyruvate are formed Glyceraldehyde-3-phosphate (G3P)  Step     A redox reaction generates NADH. 5 6 9 NAD  5 NAD  ENERGY PAYOFF PHASE NADH P 6 NADH P 6 +H +H P P P P 1,3 -Diphosphoglycerate  Steps     –      ATP and pyruvate are produced. 6 9 ADP ADP 6 7 7 ATP ATP P P 3 -Phosphoglycerate 7 P P 8 8 2-Phosphoglycerate 8 H2O H2O P P Phosphoenolpyruvate (PEP) ADP 9 ADP 9 9 ATP ATP Pyruvate Figure 6.7C

CELL RESPIRATION 3. Oxidation: Removal of electrons (energy) & transfer to NAD+ NADH 4. ATP Generation: 4 reactions that convert G3P to Pyruvate - Generates 2 ATP per Pyruvate

CELL RESPIRATION At the end of Stage 1 (Glycolysis) two molecules of pyruvate have been formed. Pyruvate moves from the cytoplasm into the mitochondria. NAD+ NADH H+ Glucose 2 Pyruvate ATP 2 P 2 ADP +

CELL RESPIRATION Glycolysis Results in: Glucose 2 molecules Pyruvate Each pyruvate 2 ADP 2 ATP Each G3P 2 NAD+ NADH

CELL RESPIRATION B. Oxidation of Pyruvate: Occurs in mitochondrion 1. Aerobic conditions Pyruvate OXIDIZED to Acetyl CoA 2. Anaerobic conditions result in FERMENTATION REACTIONS

CELL RESPIRATION

CELL RESPIRATION

CELL RESPIRATION FERMENTATION REACTIONS: 1.Lactic Acid Fermentation: Pyruvate REDUCED to Lactate No CO2 removal NADH NAD+ 2. Alcohol Fermentation: Fungal (Yeast) Cells Pyruvate REDUCED to Alcohol CO2 Removed; NADH NAD+

CELL RESPIRATION

CELL RESPIRATION

CELL RESPIRATION C. KREBS CYCLE: 1. “Priming” Reactions Prepares molecule for energy extraction Acetyl CoA (2C) joins oxaloacetate (4C) to form Citrate (6C) Citrate isomerizes to Isocitrate Krebs Cycle/ Citric Acid Cycle Video

CELL RESPIRATION

CELL RESPIRATION C. KREBS CYCLE: 2. “Energy Extraction” Oxidation rxns disassemble the molecule Decarboxylation Reactions Reduction NAD+ NADH Reduction FAD+  FADH2 Regeneration oxaloacetate

CELL RESPIRATION

CELL RESPIRATION D. ELECTRON TRANSPORT System of REDOX reactions Series of membrane electron carriers Ubiquinone (quinone molecule) Cytochromes (contain Fe++) OXYGEN is final electron acceptor Water is final product (two H+) attach to oxygen

CELL RESPIRATION

CELL RESPIRATION D. ELECTRON TRANSPORT: The movement of electrons down the concentration gradient to O2 (the final acceptor) sends protons (H+) to the intermembrane space ETC Video Video clip Protons move thru ATP synthase making ATP from ADP (Oxidative Phosphorylation) Gradients (ATP Synthase) video

Carriers bind and release electrons in redox reactions Most ATP production occurs by Oxidative Phosphorylation Most of the carrier molecules are included in the three main protein complexes Carriers bind and release electrons in redox reactions Intermembrane space Inner mitochondrial membrane Mitochondrial matrix Protein complex Electron flow Electron carrier NADH NAD+ FADH2 FAD H2O ATP ADP ATP synthase H+ + P O2 Electron Transport Chain Chemiosmosis . OXIDATIVE PHOSPHORYLATION + 2 1 2 Figure 6.10

Resulting H+ gradient stores potential energy Energy released redox reactions sed to pump H+ into the space between the mitochondrial membranes Resulting H+ gradient stores potential energy In chemiosmosis, the H+ diffuses back through the inner membrane through ATP synthase complexes Driving the synthesis of ATP Intermembrane space Inner mitochondrial membrane Mitochondrial matrix Protein complex Electron flow Electron carrier NADH NAD+ FADH2 FAD H2O ATP ADP ATP synthase H+ + P O2 Electron Transport Chain Chemiosmosis . OXIDATIVE PHOSPHORYLATION + 2 1 2 Figure 6.10

CELL RESPIRATION ENERGY (ATP) YIELD per GLUCOSE Glycolysis: 2 ATP (substrate level phosphorylation) Ox. of Pyruvate: 2 NADH (3 ATP per) Krebs Cycle: 6 NADH (3 ATP per) 2 FADH2 (1-2 ATP per) 2 ATP via GTP Electron Transport: 32 ATP (oxidative phosphorylation)

CELL RESPIRATION

CELL RESPIRATION Alternate Sources for Metabolism Glycolytic pathway thru ETS is “final common pathway” Other macromolecules can be utilized Lipids via β-oxidation Proteins via deamination (NH3) Nucleic Acids via deamination

CELL RESPIRATION

CELL RESPIRATION Control of Glucose Catabolism Feedback inhibition Phosphofructokinase inhibited by: ATP levels Citrate levels Phosphofructokinase stimulated by ADP levels AMP levels

CELL RESPIRATION There is a mutualistic symbiotic relationship between the products of glycolysis and the reactants for photosynthesis. This is an interrelationship between the mitochondria and chloroplast.

CELL RESPIRATION