Cellular Respiration 9-1 – 9-2

Chemical Energy and Food All living things consume and use energy Heterotrophs take in food which is digested and broken down into C6H12O6 Autotrophs can’t “eat” so they make C6H12O6 through photosynthesis Mitochondria then transform the “food energy” into chemical energy ( ) ATP

Chemical Energy and Food Calories Unit of measurement for energy Amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius Nutrition information on food is Calories (1000 calories)

Chemical Energy and Food Calories 1 gram of glucose (sugar) produces 3811 calories when burned A lot of energy for a cell Our bodies use glycolysis and cellular respiration to gradually release energy in food

Overview of Cellular Respiration Mitochondria “make change” energetically Take the energy in a sugar and convert it into more conveniently-sized packages  ATP

Overview of Cellular Respiration Definition: process that releases energy by breaking down glucose and other food molecules Requires oxygen

Overview of Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy ATP Carbohydrate Oxygen Carbon dioxide Water

Overview of Cellular Respiration Step 1: Glycolysis Step 2: Krebs cycle Step 3: Electron transport chain

Overview of Cellular Respiration CYTOPLASM: Glycolysis Outer membrane MATRIX: Breakdown of pyruvic acid, Krebs cycle INNER MEMBRANE: Electron transport chain MITOCHONDRION

Step 1: Glycolysis Occurs in cytoplasm of ALL cells Does not require oxygen Process of splitting a glucose (C6H12O6) molecule in half

Step 1: Glycolysis Products: 2 pyruvic acid molecules What you get when you split glucose in half Used in Krebs cycle Energized electrons Carried to the electron transport chain (ETC) by Used to generate NADH ATP

Step 1: Glycolysis Products: 2 Net yield = 2 Uses up 2 ATP Produces 4 ATP Net yield = 2 ATP ATP

Step 1: Glycolysis 1 Glucose C6H12O6

Step 1: Glycolysis ATP 2 2 ADP 1 Glucose C6H12O6

Step 1: Glycolysis ATP 2 2 ADP P 1 Glucose C6H12O6 P 2 PGAL

Step 1: Glycolysis ATP 2 2 ADP 4ADP + 4 Pi 4ATP 1 Glucose C6H12O6 2 NAD+ 2 NADH P 2 PGAL To ETC

Step 1: Glycolysis ATP 2 2 ADP 4ADP + 4 Pi 4ATP 1 Glucose C6H12O6 2 Pyruvic acid 2 NAD+ 2 NADH P 2 PGAL To ETC

Step 1: Glycolysis If oxygen is present pyruvic acid molecules enter the mitochondria for the Krebs cycle Leads to production of lots of If oxygen is absent pyruvic acid molecules stay in the cytoplasm for fermentation No more ATP is produced  ATP

Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate ATP Carbohydrate Oxygen Carbon dioxide Water

Cellular Respiration Step 1: Glycolysis Step 2: Krebs cycle Step 3: Electron transport chain

Step 2: Krebs Cycle Requires oxygen If there is no oxygen present pyruvic acid stays in the cytoplasm and does fermentation

Step 2: Krebs Cycle Involves first breaking down pyruvic acid formed during glycolysis Occurs as pyruvic acid crosses the mitochondrial membrane Rest of the cycle occurs in the mitochondrial matrix

Step 2: Krebs Cycle Products: 3 CO2 2 Lots more energized electrons Exhaled 2 Lots more energized electrons Carried to ETC by and Used to generate more ATP NADH FADH2 ATP

Step 2: Krebs Cycle – Break Down of Pyruvic Acid CYTOPLASM Mitochondrial membrane MITOCHONDRION To ETC 3 carbons NADH NAD+ TO KREBS CYCLE Co-A Pyruvic acid (from glycolysis) Acetyl Co-A Co-A CO2 Exhaled

KREBS CYCLE Co-A Co-A FADH2 FAD Citric NADH Acid NAD+ CO2 4 carbon compound NAD+ NADH ATP 5-carbon compound ADP NADH NAD+ CO2

Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate ATP Carbohydrate Oxygen Carbon dioxide Water

Cellular Respiration Step 1: Glycolysis Step 2: Krebs cycle Step 3: Electron transport chain

Cellular Respiration CYTOPLASM MITOCHONDRION Outer membrane Inner membrane Mitochondrial matrix MITOCHONDRION Intermembrane space

Step 3: Electron Transport Chain Happens on inner membrane of mitochondria Major production of Uses energized electrons delivered by and created during glycolysis and the Krebs cycle ATP NADH FADH2

Step 3: Electron Transport Chain Energized electrons are passed along a series of molecules embedded in the inner mitochondrial membrane ETC molecules take the electrons’ energy Uses energy to make ATP

Step 3: Electron Transport Chain CYTOPLASM OUTER MEMBRANE ELECTRON TRANSPORT CHAIN INTER MEMBRANE SPACE INNER MEMBRANE MITOCHONDRIAL MATRIX

Step 3: Electron Transport Chain Oxygen is the final electron acceptor If oxygen is not present electrons stop flowing through ETC ATP production stops Combines with H+ ions to form water

Step 3: Electron Transport Chain CYTOPLASM OUTER MEMBRANE ELECTRON TRANSPORT CHAIN INTER MEMBRANE SPACE INNER MEMBRANE MITOCHONDRIAL MATRIX

Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate ATP Carbohydrate Oxygen Carbon dioxide Water

Overall ATP Production FOR EVERY GLUCOSE MOLECULE: ATP Glycolysis produces 2 ATP Krebs cycle produces 2 Electron transport chain produces **32 ATP **Makes ATP from electrons carried to it from the first 3 steps

Overall ATP Production cellular respiration makes 36

Fermentation Occurs when there is no oxygen available

Fermentation Pyruvic acid molecules are still formed through glycolysis Occurs in the cytoplasm Mitochondria are not involved Pyruvic acid is broken down differently: No ATP is produced after glycolysis

Fermentation 2 types: Alcoholic fermentation Lactic acid fermentation

Alcoholic Fermentation Ethyl alcohol and CO2 are byproducts Occurs in organisms that live in environments lacking oxygen

Alcoholic Fermentation Glycolysis 2 CO2 2 Ethanol

Alcoholic Fermentation Example: yeast When spores are placed in a food-rich, oxygen-free environment the organisms come to life Begin doing alcoholic fermentation CO2 produced makes bread rise Tiny amounts of alcohol produced evaporate as bread bakes

Lactic Acid Fermentation Performed by cells when they run out of oxygen After glycolysis pyruvic acid is transformed into lactic acid Causes burning sensation in muscles

Lactic Acid Fermentation Glycolysis Glucose Pyruvic acid Lactic acid

Energy and Exercise Muscle cells use tremendous amounts of ATP to contract and create movement Cells keep a small amount of ATP on hand Enough for only a few seconds of intense exercise After that ATP is produced by lactic acid fermentation

Energy and Exercise Lactic acid fermentation can provide ATP for about 90 seconds of intense exercise Lactic acid is produced by a series of reactions that require extra oxygen Reason for breathing heavily at the end of a longer race

Energy and Exercise Cellular respiration is the only way to generate ATP after 90 seconds Slow process Why a marathon and a sprint look differently

Energy and Exercise Cellular respiration is the only way to generate ATP after 90 seconds Slow process Why a marathon and a sprint look differently Training allows a person to exercise more vigorously beyond the 90 second barrier

Energy and Exercise Fuel for making ATP is stored as glycogen Carbohydrate Body contains enough glycogen to fuel cellular respiration for 15-20 minutes Body burns fat after that