Cells and Energy Chapter 4 Mr. Scott

Cellular Respiration Organic molecules can act as fuels Organic molecules can act as fuels –Fermentation – no oxygen –Aerobic respiration – oxygen used –Cellular respiration  Both aerobic and anaerobic

Oxidation-Reduction Relocating electrons in organic molecules can release energy Relocating electrons in organic molecules can release energy –Can be used to produce ATP Redox reactions Redox reactions –Lose electrons-oxidation –Gain electrons-reduction

Electron Carriers Energy release must be done sequentially Energy release must be done sequentially In cell respiration electrons are removed from glucose stepwise and transferred to carriers In cell respiration electrons are removed from glucose stepwise and transferred to carriers –NAD+ –FAD+

Electron Transport Chain Proteins embedded in the inner matrix of the mitochondria Proteins embedded in the inner matrix of the mitochondria –Electrons move from carriers through the chain to final acceptor  Oxygen Glucose NADH ETC Oxygen

Cellular Respiration Cellular Respiration Cellular Respiration –Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.  Cellular respiration - If oxygen is present for glycolysis then Krebs cycle and the electron transport chain come after –6O 2 + C 6 H 12 O 6  6CO 2 + 6H 2 O + Energy

Cellular Respiration Stages of Cellular Respiration Stages of Cellular Respiration 1.Glycolysis 2.Pyruvate oxidation and citric acid cycle (Krebs Cycle) 3.Oxidative phosphorylation – electron transport chain

Glycolysis Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3- carbon compound Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3- carbon compound

Cellular Respiration – ATP Production  2 ATP molecules are used in the production  4 ATP molecules are produced  2 ATP molecules are gained or there is a 2 net gain

Krebs and Electron Support Krebs and electron transport Krebs and electron transport After glycolysis After glycolysis –90% of total energy is still unused  Aerobic – Require oxygen

Krebs and Electron Support Krebs Cycle Krebs Cycle –Also called the citric acid cycle –Pyruvic acid is broken down into 3 CO 2 in a series of energy- extracting reactions

Krebs and Electron Support – Citric acid production  Pyruvic acid comes into the mitochondrion  One carbon breaks off as CO 2  The other two carbons combine with coenzyme A forming Acetyl-CoA  Acetyl-CoA combines with a 4-carbon molecule to make citric acid

Krebs and Electron Support –Energy extraction  Citric acid is broken down and electrons are transferred to electron carriers –One carbon is removed, then another carbon  Making CO 2  This is why you exhale CO 2 –ATP is produced (NOT MUCH)  It is used for cell activities –NAD + and FAD  Convert to NADH and FADH 2  Can produce large amounts of ATP

Electron Transport Chain Electron Transport Electron Transport –The electron transport chain uses high-energy electrons from the Krebs cycle to convert ADP into ATP

Electron Transport Chain –Electron transport  High-energy electrons are transferred from NADH and FADH 2 to the electron transport chain  These electrons connect to hydrogen and oxygen to make water

Electron Transport Chain –Hydrogen ion movement  Two high-energy electrons cause a H + to move across the cell membrane  This makes the inside of the mitochondria positively charged –ATP production  H + ions leave the mitochondria causing the ATP synthase to spin making one ATP from one ADP for each rotation

Electron Transport Chain More totals More totals –1 NADH gives 10 H + ions being transported –Most research suggests 4 H + to produce 1 ATP – 1 NADH produces 2.5 ATP (FADH 2 produces 1.5 ATP)

Krebs and Electron Support The Totals The Totals –Glycolysis  2 ATP/Glucose molecule –Krebs cycle and Electron transport chain  34 ATP/Glucose molecule –Total  30 – 32 ATP/Glucose  34% of total energy of glucose

Cellular Respiration Fermentation Fermentation –Process that releases energy from food molecules by making ATP without oxygen.  Anaerobic –Process that does NOT require oxygen

Cellular Respiration –Alcoholic Fermentation  pyruvic acid + NADH  alcohol + CO 2 + NAD + –Yeast in the bread dough causes this process to make bread rise

Cellular Respiration –Lactic Acid Fermentation  pyruvic acid + NADH  lactic acid + NAD + –This is why your muscles burn –This process is used to make cheese, yogurt, buttermilk, and sour cream

Comparing Pathways Glycolysis/FermentationAnaerobic Respiration Aerobic Respiration GlycolysisYes Oxidizing agentNAD+ Oxidizing mechanism Final electron acceptor is pyruvate or acetylaldehyde Final electron alcohol or lactic acid Final electron acceptor oxygen ATP production4 (net 2)228-32

Fuel Sources Multiple types of carbs can pass through glycolysis Multiple types of carbs can pass through glycolysis Proteins can be fuel Proteins can be fuel –Must be broken into amino acids first Fats are excellent energy source Fats are excellent energy source –Provides twice as much ATP as carbs

Control of Cellular Respiration Cell Respiration is simple supply and demand Cell Respiration is simple supply and demand –Use of phosphofructokinase  Allosteric enzyme –Inhibitted by ATP –Activated by AMP  Inhibition slows down glycolysis