All living organisms need energy CELLULAR RESPIRATION All living organisms need energy

Cellular Respiration Harvesting Chemical Energy ATP 2009-2010

INTRODUCTION TO CELLULAR RESPIRATION Introduction: All living organisms need energy Respiration: the life process by which organisms convert the chemical energy stored in food to a form of energy more easily utilized by the cell Process of Cell Respiration: a biochemical process used by cells to release energy from organic molecules (food) such as glucose ~this energy is stored in the molecule ATP ~ ATP = adenosine triphosphate or A~P~P~P ~ the process is controlled by enzymes

Harvesting energy stored in food Cellular respiration breaking down food to produce ATP in mitochondria using oxygen “aerobic” respiration usually digesting glucose but could be other sugars, fats, or proteins ATP food O2 Movement of hydrogen atoms from glucose to water glucose + oxygen  energy + carbon + water dioxide C6H12O6 6O2 ATP 6CO2 6H2O  +

What do we need to make energy? The “Furnace” for making energy mitochondria Fuel food: carbohydrates, fats, proteins Helpers oxygen enzymes Product ATP Waste products carbon dioxide then used by plants water Make ATP! Make ATP! All I do all day… And no one even notices! food ATP enzymes CO2 H2O O2

Mitochondria are everywhere!! animal cells plant cells

Using ATP to do work? Can’t store ATP too unstable only used in cell that produces it only short term energy storage carbohydrates & fats are long term energy storage Adenosine TriPhosphate work Adenosine DiPhosphate ADP A working muscle recycles over 10 million ATPs per second Whoa! Pass me the glucose & oxygen!

{ { { ATP A Body’s Energy Budget make energy eat food synthesis 1 make energy • energy needed even at rest • activity • temperature control { ATP eat food • growth • reproduction • repair { 2 synthesis (building) • glycogen (animal starch) • fat { 3 storage

Aerobic Cellular Respiration Aerobic = with oxygen Occurs in the mitochondria The use of oxygen releases more energy per glucose molecule than anaerobic = without oxygen Uses oxygen but releases carbon dioxide and water SUMMARY EQUATION:

Breathing and cellular respiration are closely related CO2 Lungs CO2 Bloodstream Muscle cells carrying out O2 CELLULAR RESPIRATION Sugar + O2  ATP + CO2 + H2O

Oxidation-Reduction Reactions Redox for short Oxidation= loss of electrons (or H+) Reduction= gain of electrons (or H+) OIL RIG: Oil = Oxidation is loss Rig = Reduction is gain ~chemical reaction which involve a partial or complete transfer of electrons form one reactant to another ~ a coupled reaction Cell Respiration is a redox process that transfers hydrogen form sugar to oxygen oxidation C6H12O6 + 6O2 -- 6CO2 + 6H2O + ATP( energy) reduction

Hydrogen carriers such as NAD+ shuttle electrons in redox reactions Enzymes remove electrons from glucose molecules and transfer them to a coenzyme / electron carriers[ NADH & FADH2]

Redox reactions release energy when electrons “fall” from a hydrogen carrier to highly electronegative oxygen NADH ( & FADH2) delivers electrons to a series of electron carriers in an electron transport chain As electrons move from carrier to carrier, their energy is released in small quantities Energy released and now available for making ATP ELECTRON CARRIERS of the electron transport chain

STAGES OF CELLULAR RESPIRATION Respiration occurs in three main stages High-energy electrons carried by NADH ELECTRON TRANSPORT CHAIN GLYCOLYSIS KREBS CYCLE Cytoplasmic fluid Mitochondrion

1. Glycolysis: [Glyco=sweet, sugar lysis = to split] ~process in which one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid, a 3-carbon compound ~ takes place in cytoplasm ~ makes 2 ATP {part of anaerobic respiration too] ~NO OXYGEN NEEDED ~ 2 molecules of NADH are formed Pyruvic acid Glucose

2. Krebs Cycle Each pyruvic acid molecule is broken down to form CO2 and a two-carbon acetyl group, which enters the Krebs cycle [Transition phase] The Krebs cycle completes the oxidation of organic fuel, generating many NADH and FADH2 molecules 2 turns per glucose molecule Occurs in mitochondria Produces 2 ATP 6 NADH & 2 FADH2 Acetyl CoA CO2 KREBS CYCLE

3. Electron Transport Chain In the electron transport chain, the carrier molecules NADH and FADH2 give up electrons that pass through a series of reactions. Oxygen is the final electron acceptor forming water. This sets up a H+ (proton) gradient Allow the protons to flow through ATP synthase which synthesizes ATP (ADP + Pi = ATP) Produces 32 ATP Occurs in the inner mitochondrial membrane the electron transport chain adds 32 ATP molecules

What if oxygen is missing? No oxygen available = can’t complete aerobic respiration Anaerobic respiration also known as fermentation alcohol fermentation lactic acid fermentation no oxygen or no mitochondria (bacteria) can only make very little ATP large animals cannot survive yeast bacteria

Fermentation is an anaerobic alternative to aerobic respiration Process operates by means of chemical reactions catalyzed by enzymes in cytoplasm of cell Primary mode of energy production for some bacteria and fungi (yeast) use glycolysis alone to produce small amounts of ATP Important in production of foods such as cheese, buttermilk, yogurt, alcohol, (wine/beer) and bread 2 types: 1. alcohol & 2. lactic acid

Anaerobic Respiration Fermentation alcohol fermentation yeast glucose  ATP + CO2+ alcohol make beer, wine, bread lactic acid fermentation bacteria, animals glucose  ATP + lactic acid bacteria make yogurt animals feel muscle fatigue Tastes good… but not enough energy for me!

Alcoholic Fermentation glucose -> pyruvic acid-> 2 ethyl alcohol + 2 CO2 2ATP GLYCOLYSIS FERMENTATION

Lactic Acid Fermentation Glucose->pyruvic acid -> 2 lactic acid 2ATP GLYCOLYSIS FERMENTATION ~ used to make cheese and yogurt ~ in humans during strenuous exercise not enough oxygen from blood “oxygen debt” ~ lactic acid accumulates in muscle; leads to fatigue and pain Will be converted back to pyruvic acid in liver Both types a of fermentation are considered inefficient , only produce 2ATP from glycolysis

Cells use many kinds of organic molecules as fuel for cellular respiration Polysaccharides Fats Proteins Sugars Cellular respiration

Comparing Cellular Respiration & Photosynthesis Cell Respiration Photosynthesis