Cell Respiration Chapter 9 Prentice Hall pg. 220-233 9–1 Chemical Pathways A Chemical Energy and Food B. Overview of Cellular Respiration C. Glycolysis 1. ATP Production 2. NADH Production D. Fermentation 1.Alcoholic Fermentation 2.Lactic Acid Fermentation 9–2 The Krebs Cycle and Electron Transport A. The Krebs Cycle B. Electron Transport C. The Totals D. Energy and Exercise 1. Quick Energy 2. Long-Term Energy E. Comparing Photosynthesis and Cellular Respiration

How much energy is present in food? 1 gram of glucose (C6H12O6) when burned in the presence of oxygen releases 3811 calories This process takes place in the mitochondrion of both plants and animals

Cellular respiration - the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen (energy trapped in ATP molecules) Equation: 6O2 + C6H12O6  6CO2 + 6H20 + Energy Two types of cellular respiration include aerobic (with O2) and anaerobic (without O2)

Electron Transport Chain Aerobic respiration - includes 3 main steps; can remove about 38% of energy from glucose; powers all energy for life; occurs in the cytoplasm and mitochondria Glucose Glycolysis Cytoplasm Pyruvic acid Electrons carried in NADH Krebs Cycle Electrons carried in NADH and FADH2 Electron Transport Chain Mitochondrion

First Step- Glycolysis glycolysis - the process by which glucose is converted to pyruvic acid (pyruvate) and energy is released Products (net gain) 2 ATP made for energy 2 energy shuttle (NADH) sent to ETC to make ATP 2 Pyruvate will be used to start Krebs Cycle in the mitochondria Does not require the presence of oxygen (can happen in both aerobic and anaerobic reactions) Frees 2 % of the energy in glucose Takes place in the cytoplasm of the cell

To the electron transport chain Glycolysis Review (net gain) 2 ATP made for energy 2 energy shuttle (NADH) sent to ETC to make ATP 2 Pyruvate will be used to start Krebs Cycle in the mitochondria Glucose To the electron transport chain 2 Pyruvic acid

Second Step- Krebs cycle 2) Krebs cycle – uses pyruvic acid from glycolysis and releases energy and CO2 Series of energy extracting reactions named after Hans Krebs, Nobel prize 1953 (discovery of this step) also called citric acid cycle Products CO2 – exhaled as a waste product (autotrophs use in photosynthesis) 2 ATP made- used for cell’s life processes 8 energy shuttles (NADH, FADH2)- sent to ETC to make ATP takes place in mitochondrial matrix

Third Step- Electron Transport Chain electron transport- produces 32 ATP from energy shuttles sent from glycolysis and Kreb’s cycle Products: Electrons, hydrogen, and energy are added to oxygen to make water 32 ATP made- (90% of ATP made here) Occurs across the inner mitochondrial membrane

Total energy produced from aerobic respiration from 1 glucose = 36 ATP

Aerobic Respiration (conclusion) 38 % efficient (some energy lost as heat) 62% is released is heat (one of the reasons why your body feels warmer after exercise) 1 glucose molecule = (yields) 36 ATP made (energy) ATP made form glucose provides energy to sleep, exercise, eat and study biology (allows our cells to function properly)

Shows energy that is made in the ETC from NADH and FADH2 molecules

Review of Aerobic Respiration Glucose (C6H1206) + Oxygen (02) Glycolysis Krebs Cycle Electron Transport Chain Carbon Dioxide (CO2) Water (H2O)

Two Kinds of fermentations 1) Alcoholic fermentation Fermentation – when oxygen is not present (anaerobic), glycolysis is followed by a different pathway; releases energy from food in the absence of oxygen Organisms live on small amounts of ATP that comes from glycolysis (only 2 ATP per glucose) Role of fermentation is to recharge low energy molecules so that glycolysis can continue to proceed in the absence of 02 Two Kinds of fermentations 1) Alcoholic fermentation 2) Lactic Acid fermentation

(Anaerobic) Alcoholic Fermentation Characteristic of some yeast and bacteria Begins with glycolysis and ends with alcohol and CO2 Alcohol is toxic to cells Causes bread to rise; yeast in dough runs out of oxygen begins to ferment, giving off bubbles of CO2 forms the air spaces that you see in a slice of bread small amount of alcohol produced, evaporates when the bread is baked

(Anaerobic) Lactic acid Fermentation Characteristic of many organisms including animals and bacteria Pyruvic acid is converted into lactic acid Lactic acid is produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissues Without enough oxygen, the body is not able to produce all of the ATP that is required Muscle cells begin to produce ATP by Lactic Acid fermentation Lactic acid builds up causing soreness, burning and muscle fatigue in animals Lactic acid can be removed from affected cells and detoxified by the liver Unicellular organisms also produce lactic acid as a waste product during fermentation Helps to make cheese yogurt, buttermilk, and sour cream

Energy and Exercise Quick Energy(quick race) Beginning of race bodies uses 3 ATP Muscles contain only enough ATP for the first few seconds Past the 50 m mark ATP is gone Muscles will then need to produce ATP through lactic acid fermentation Makes enough ATP to last 90 seconds (200-300 m sprint) Long Term Energy (soccer game~1 hour) Must go through cell respiration to make enough ATP Respiration is slower than fermentation (this is why athletes must pace themselves) Muscles use energy from glycogen (first 15-20 minutes) and then go to fats for energy Explains why aerobic exercise is effective for weight loss

Comparison of Aerobic vs. Anaerobic Respiration Glucose Glycolysis Krebs cycle Electron transport Fermentation Alcohol (with oxygen) Lactic acid (without oxygen)

Glucose Glycolysis Kreb’s Cycle Fermentation Lactic Acid

Comparison of Fermentation to Cellular Respiration Anaerobic Respiration Aerobic Respiration Lactic Acid Alcoholic Cellular respiration glucose glucose glucose glycolysis (pyruvic acid) glycolysis (pyruvic acid) glycolysis (pyruvic acid) carbon dioxide carbon dioxide lactic acid water alcohol 2 ATP 2 ATP 36 ATP

Aerobic Cellular Respiration

Comparing Photosynthesis and Cellular Respiration Energy flows in opposite directions Photosynthesis “deposits” energy Cellular Respiration “withdraws” energy CO2 glucose glucose H2O ATP mitochondria light sun C6H12O6 ATP glucose glucose 36

Energy from sun stored in glucose Carbon dioxide taken in Cellular Respiration Photosynthesis Food synthesized Food broken down Energy from sun stored in glucose Energy of glucose released Carbon dioxide taken in Carbon dioxide given off Oxygen given off Oxygen taken in Produces sugars Produces CO2 and H2O Requires light Does not require light Occurs only in presence of chlorophyll Occurs in all living cells Comparison of Photosynthesis and Cellular Respiration Cell Respiration

Chloroplast Sunlight Photosynthesis CO2, H2O O2, glucose Mitochondria Cellular Respiration ATP + Heat