O2 + C6H12O6 CO2 + H2O + ATP What is it? • The chemical pathway that provides living organisms with energy by breaking down foods • The process releases the energy from the foods you eat or the calories you intake calorie – the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius Food labels - kilocalories (C) Kilocalorie 1000 calories QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Three Main Steps: 1) Glycolysis If oxygen is available 2) Krebs Cycle 3) The Electron Transport Chain The “powerhouse” of the Cell QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. What is Glycolysis? • The process that breaks glucose (6 carbon sugar) apart into two 3 carbon sugars called pyruvic acid • It requires 2 ATP from the cell to start • It produces 4 ATP and the electron carrier, NADH • Outcome: 2 ATP + 2 NADH molecules NAD+ + 2e- NADH What was an electron carrier? • NADPH in photosynthesis was used to carry energy to the Calvin cycle • NADH holds high energy electrons in order to carry their energy to the Electron transfer chain in respiration A closer look at glycolysis… • Where do you think it occurs? • Does it require oxygen to take place? • It occurs quickly • Does it generate a lot of cell energy? How much? • What happens next? If no oxygen is present… Fermentation – a method used to generate energy for the cell even when no oxygen is available What does it need to do? - Regenerate NAD+ so it can pick up more electrons during glycolysis and continue ATP production This is why NAD+ must be regenerated in order for glycolysis to occur Two Types of Fermentation: 1) Alcoholic Fermentation Pyruvic acid + NADH NAD+ + CO2 + alcohol Occurs in yeast; used for bread rising (forming air spaces in bread) and alcoholic beverage production Two Types of Fermentation 2) Lactic Acid fermentation Pyruvic acid + NADH lactic acid + NAD+ Occurs during strenuous exercise when you can’t get enough oxygen to your muscles; causes burning feeling in muscles Occurs in bacterial cells during cheese, yogurt and sour cream production Classwork/Homework First, complete the Glycolysis and Fermentation worksheet and then, 9-1 Section Assessment page 225, #1-6 1. Describe the process of cellular respiration 2. What are the products of glycolysis? 3. Name the two main types of fermentation. 4. What is a calorie? Calorie? 5. How is the function of NAD+ similar to that of NADP+? 6. How are lactic acid fermentation and alcoholic fermentation different? How are they similar?