Bellringer-April 22, 2015 FILL IN THE LETTERS

Overview of Cellular Respiration H. Biology Ms. Kim

Energy Flows into ecosystems as sunlight and leaves as heat Light energy ECOSYSTEM CO 2 + H 2 O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 ATP powers most cellular work Heat energy

Carbon Cycle

Reminder…. Anabolic pathways (“ A” for add together) Anabolic pathways (“ A” for add together)  Build molecules from simpler ones (ex: photosynthesis)  Consume energy ( endergonic or endothermic) Catabolic pathways ( “ C” for cut in parts) Catabolic pathways ( “ C” for cut in parts)  Break down complex molecules into simpler compounds (ex: cell respiration)  Release energy ( exergonic or exothermic)

Cellular respiration  Most efficient catabolic pathway  Consumes O 2 and organic molecules (ex: glucose) To keep working cells must regenerate ATP  Yields ATP  To keep working cells must regenerate ATP

Catabolic pathways yield energy by oxidizing organic fuels The breakdown of organic molecules is exergonic (exothermic) fermentation One catabolic process, fermentation  Is a partial degradation of sugars that occurs without oxygen cellular respiration Another example is cellular respiration

Cellular respiration Occurs in mitochondria  similar to combustion of gas in an engine after O 2 is mixed with hydrocarbon fuel. Food and O 2 = fuel for respiration. The exhaust =CO 2 and H 2 O. The overall process is: organic compounds + O 2  CO 2 + H 2 O + energy (ATP + heat) (ATP + heat)  Carbohydrates, fats, and proteins can all be used as the fuel, but most useful is glucose.

Mitochondria Intermembrane Space Powerhouse of the cell! The organelle responsible for cellular respiration The Krebs Cycle and ETC take place here  ATP is produced here! It is a double membrane with the inner membrane highly folded (to increase the surface area and make the mitochondria more efficient).

Mitochondrion Structure

Outer membrane – similar to plasma membrane; contains integral proteins Inner membrane - NOT permeable to ions (needs help to cross); there is a membrane potential across the inner membrane; contains ATP synthase Cristae – large surface area due to folding Matrix - gel-like in middle or lumen; many contains enzymes for cellular respiration

RECALL…Redox Reactions Catabolic pathways yield energy  Due to the transfer of electrons Redox reactions Redox reactions  Transfer e-’s from one reactant to another by oxidation and reduction In o xidation In o xidation  Substance l o ses e-s (it’s oxidized) In r eduction In r eduction  Substance r eceives e-s (it’s reduced)

Examples of redox reactions Na + Cl Na + + Cl – becomes oxidized (loses electron) becomes reduced (gains electron) Xe- + Y  X + Ye- **energy must be added to remove e- X = e- donor = reducing agent and reduces Y. Y = e- recipient = oxidizing agent and oxidizes X.

Oxidation of Organic Fuel Molecules During Cellular Respiration During cellular respiration – Glucose is oxidized – oxygen is reduced – E-’s lose potential energy  energy is released C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy becomes oxidized becomes reduced

NAD+ or FAD Electrons are not transferred directly to oxygen but are passed first to a coenzyme called NAD+ or FAD NAD + H O O OO–O– O O O–O– O O O P P CH 2 HO OH H H HOOH HO H H N+N+ C NH 2 H N H N N Nicotinamide (oxidized form) NH 2 + 2[H] (from food) Dehydrogenase Reduction of NAD + Oxidation of NADH 2 e – + 2 H + 2 e – + H + NADH O H H N C + Nicotinamide (reduced form) N Figure 9.4 NAD+ and FAD= e- acceptor and oxidating agent

2 H 1 / 2 O 2 (from food via NADH) 2 H e – 2 H + 2 e – H2OH2O 1 / 2 O 2 Controlled release of energy for synthesis of ATP ATP Electron transport chain Free energy, G (b) Cellular respiration + Electron Flow = food  NADH/FADH 2  ETC  oxygen

Cellular Respiration – Background info Equation – C 6 H 12 O 6 + 6O 2 → 6CO H 2 O + 36 or 38 ATP -When food is broken down, energy is released gradually and stored in ATP. -Respiration is done by BOTH plants and animals

The Stages of Cellular Respiration Respiration is a cumulative process of 3 metabolic stages 1. Glycolysis 2. Kreb’s Cycle (The citric acid cycle) 3. Electron Transport Chain (Oxidative phosphorylation)

The 3 Stages Glycolysis Glycolysis  Breaks down glucose into 2 molecules of pyruvate  Makes NADH  Makes a little bit of ATP Kreb’s Cycle (Citric acid cycle) Kreb’s Cycle (Citric acid cycle)  Completes the breakdown of glucose  Makes NADH and FADH 2  CO 2 is waste product  Makes a little bit of ATP Oxidative phosphorylation) Electron Transport Chain (Oxidative phosphorylation)  Driven by the electron transport chain  Generates ALOTTTTT of ATP  O 2 is the final electron acceptor and gets reduced to make WATER

General overview – Cellular Respiration 1.Glycolysis: In the cytosol Anaerobic Turns glucose to 2 pyruvate  net gain of 2 ATP and 2 NADH 1.Glycolysis: In the cytosol Anaerobic Turns glucose to 2 pyruvate  net gain of 2 ATP and 2 NADH 2. Krebs: In the mitochondrial matrix Makes little ATP, NADH, and FADH 2 (electron taxis) Passes e- to ETC 2. Krebs: In the mitochondrial matrix Makes little ATP, NADH, and FADH 2 (electron taxis) Passes e- to ETC 3. ETC → uses chemiosmosis to make LOTS of ATP

Exit Slip-April 22, 2015 Draw a cycle of the ecosystem between photosynthesis and cellular respiration. Include the following: photosynthesis, carbon dioxide, light energy, heat energy, oxygen, glucose, water, and ATP.