I. Chemical Energy and Food • Food provides living things with the chemical building blocks they need to grow and reproduce • Cells use fats, proteins and carbs as food • Break this food down gradually
II. Overview of Cellular Respiration • Cellular respiration is the multi-step process that releases energy from food in the presence of oxygen • Represented as: + + + C6H12O6 Glucose 6O2 Oxygen 6CO2 Carbon dioxide 6H2O Water ENERGY
A. Stages of Cellular Respiration • Cellular respiration captures energy in 3 stages: • Glycolysis • Krebs cycle • Electron transport chain
How does it work? • Glucose enters chemical pathway called glycolysis - Uses some energy to make ATP, rest stored as pyruvic acid • Pyruvic acid enters the Kreb cycle • Most energy is extracted during electron transport chain by using oxygen
B. Oxygen and Energy • Oxygen is required at end of electron transport chain • Aerobic: pathways that require oxygen • Krebs, Electron transport chain • Anaerobic: pathways that do not require oxygen • Glycolysis, Fermentation
Where does this take place? • Glycolysis happens in cytoplasm • The Krebs cycle and Electron transport chain occur in mitochondria
III. Comparing Photosynthesis and Cellular Respiration • Cellular respiration is balanced by photosynthesis • Photosynthesis removes carbon dioxide from atmosphere, cellular respiration adds it • Photosynthesis adds oxygen and cellular respiration uses it to make energy from food
9.1 Assessment questions • 2a. Write the overall reaction for cellular respiration. • 2b. How does the process of cellular respiration maintain homeostasis at the cellular level? • 3a. In what ways are cellular respiration and photosynthesis considered opposite processes? • 3b. How is the chemical energy in glucose similar to money in a savings account?