Cellular Respiration Chapter 8 Starr Biology book How Cells Release Stored Energy 8.1 ATP Is Universal Energy Source Photosynthesizers get energy from the ___________ to make carbohydrates during photosynthesis Animals get energy second- or third-hand from plants or other organisms Regardless, the matter/energy is ___________ _____ and converted to the ___________ bond ___________ of ATP

Importance of Cellular Respiration Cellular respiration is the process where cells break down glucose into carbon dioxide and water, releasing energy C6H12O6(s) + O2(g)  CO2(g) + H2O(l) +energy

Respiration - chemical bonds of food molecules are broken down New bonds form in resulting chemical products ALWAYS takes energy to break chemical bonds Energy is ALWAYS released when new bonds broken More energy is released than consumed Progression of Reaction A + B  C + D ___________ ___________

Electron Carriers aka _______________ NADH Donates electrons in cellular processes NAD+ ___________ electrons in cellular processes FADH2 FAD+

L.E.O. goes G.E.R. Lose Electrons ___________ Gain Electrons ___________ O.I.L. R.I.G. Oxidation if lost Reduction if gained Reduction and Oxidation are paired reactions often called ______________ reactions. The transfer of electrons releases/traps energy HYDROGENS ALSO substitute in THESE situations

Energy for most cellular processes are supplied by: ___________ Typical human cell estimated to contain 1.0x109 molecules ATP Continually broken down to ___________ + Pi Release energy to do work Reformed to be used again

Section 8.2 Glucose A ___________ sugar (C6H12O6) Atoms held together by ___________ bonds Glucose is used by… In-text figure Page 126

Glycolysis Takes place ________ the presence of oxygen Greek for “Sugar splitting” Glucose molecule (___carbon sugar) breaks down to two pyruvate molecules (___ carbon sugar) Takes place ________ the presence of oxygen Occurs in the ___________ (cytosol) of the cell Pyruvate (pyruvic acid) moves into the mitochondria via a transport protein

Glycolysis Key Steps Energy-requiring steps Two ATP molecules are used - an ________________of energy to break glucose into 2 molecules of _____________ Energy-releasing steps Redox reactions occur 2 NAD+  2 ______ Enough energy is released to join 4 ADP molecules with 4 P molecules  this forms 4 _______ molecules

ENERGY-REQUIRING STEPS fructose–1,6–bisphosphate Glycolysis ENERGY-REQUIRING STEPS OF GLYCOLYSIS glucose ATP 2 ATP invested ADP P glucose–6–phosphate P fructose–6–phosphate ATP ADP P P fructose–1,6–bisphosphate DHAP Fig. 8-4b, p.127

Glycolysis 2 ATP produced ATP ADP P pyruvate H2O ATP ATP Fig. 8-4d, p.127 Glycolysis NADH NADH ATP ATP 2 ATP produced

Glycolysis When complete, cell has consumed one glucose molecule, 2 ATP produced 2 ATP molecules, two NADH molecules and two pyruvate molecules These ATP molecules are available to do cell work (the others continue into the next cycles) REACTANTS PRODUCTS 2 pyruvate 2 NAD+ 2 ATP 4 ADP + Pi

CELLULAR RESPIRATION- Section 8.3 Second Stage Reactions- OVERVIEW PYRUVATE OXIDATION ____________ is oxidized into two-carbon acetyl units and carbon dioxide NADH traps energy (NAD+ is reduced) CITRIC ACID CYCLE- KREBS CYCLE The acetyl units are broken down (oxidized) to __________ __________ NADH and FADH2 trap energy (NAD+ and FAD are reduced)

Pyruvate Oxidation Pyruvate oxidation is a chemical ____________ connecting glycolysis in cytoplasm with the Kreb’s cycle in the mitochondrial matrix The 2 pyruvate molecules must be transported through the _____ mitochondrial membranes into the matrix

Key Steps in Pyruvate Oxidation One __________ is removed from each pyruvate – CO2 released as a ______________ product Energy released from pyruvate trapped in ________ Remaining 2-C compounds become an acetic acid group Coenzyme A (CoA) attaches to acetic acid - forms __________________ This acetyl-CoA enters the Citric Acid Cycle- Krebs cycle

Key Steps of the Krebs Cycle Krebs cycle occurs ____________ for each molecule of glucose processed Acetyl-CoA enters and releases the CoA enzyme, which is __________________ for the next pyruvate and the Acetyl is further _________________ _____________ During one cycle three NAD+s and one FAD are ___________ forms three NADHs and one FADH2 one ADP + Pi combine to form one _________ two __________ molecules are produced and released as waste

Key Features of the Krebs Cycle ALL 6 carbon atoms of glucose have been oxidized to CO2 Released from cell as ____________ waste All that remains is some free ____________ in form of ATP and high-energy NADH and FADH2 NADH and FADH2 go on to Electron Transport Chain Here much of their energy will be ____________ to ATP

The Krebs Cycle Overall Reactants Overall Products Acetyl-CoA 3 NAD+ FAD ADP and Pi Overall Products Coenzyme A- ____________ 2 CO2 - ____________ 3 NADH - ____________ FADH2 - ____________ ATP - ____________

Section 8.4 Electron Transport Chain OVERVIEW Occurs in the inner membrane of ________________ Coenzymes deliver NADH and FADH2 to the electron transfer chain (inner membrane) Oxygen is ______________ Water is _____________ __________ is produced

Stage 4: Electron Transport and Chemiosmosis

Key Steps for Electron Transfer ___________________ AND ________________ are removed from NADH and FADH2 (releasing energy) NADH breaks down to NAD+, _______ (hydrogen ion), and _______ (electron) FADH2 breaks down to FAD+, 2H+, and 2e- Each molecule has a specific role: NAD+ and FAD+ are recycled to capture more energy The electron transfers thru membrane and providing ___________ to _________ H+ ions across inner mitochondrial membrane. This generates a H+ concentration _________________

Key Steps for Electron Transfer ATP is produced when hydrogen ions __________ back through channel protein called __________________________. This enzyme adds _________________ to ADP to generate ATP! = CHEMIOSMOSIS Each glucose molecule produces ____________ ATP molecules  The remaining H+ ions, e- and oxygen form _______________.

Summary of ATP Energy Harvest (per 1 molecule of glucose) Glycolysis ___ ATP formed Prep Step and Krebs cycle Electron Transport Chain

Where does the ATP go? After ATP molecules are formed by chemiosmosis they are transported through both mitochondrial membranes Used to drive processes requiring energy Examples:

Section 8.5 Anaerobic Pathways aka Fermentation Do _______ use oxygen Produce less ATP than aerobic pathways Two types of Fermentation Pathways ________________________ Fermentation _________________________ Fermentation

Fermentation Pathways Begins with ______________in the cytoplasm Yield only the __________ from glycolysis Steps that follow glycolysis serve only to regenerate NAD+ to capture more energy from the next glycolysis cycle

Alcoholic Fermentation used by _______and some plants glycolysis C6H12O6 2 ATP energy input 2 ADP 2 NAD+ Alcoholic Fermentation used by _______and some plants ____________________ is formed 2 NADH 4 ATP 2 pyruvate energy output 2 ATP net ethanol formation 2 H2O 2 CO2 2 acetaldehyde electrons, hydrogen from NADH 2 ethanol Fig. 8-10d, p.132

Lactic Acid Fermentation used by ____________ glycolysis C6H12O6 ATP 2 energy input 2 ADP 2 NAD+ 2 NADH 4 ATP 2 pyruvate energy output 2 ATP net Lactic Acid Fermentation used by ____________ and other microorganisms; produces Lactic Acid electrons, hydrogen from NADH 2 lactate Fig. 8-11, p.133

Questions #1-8 How does glycolysis result in a net gain of two ATP molecules? What is the role of pyruvate in cellular respiration? In what two ways is the Krebs cycle important for making ATP? How does the electron transport chain depend on the Krebs cycle? Explain the functions of electrons, hydrogen ions, and oxygen in the electron transport chain. What is the relationship between glycolysis and fermentation? How are lactic acid fermentation and alcoholic fermentation similar? Different? Describe the similarities and differences between cellular respiration and fermentation.