Cell Energy Chapter 4 Energy and Living Things
A. Autotrophs produce their own food B. Heterotrophs get food from somewhere else (what they eat) C. ATP (adenosine triphosphate) 1. When food is burned a
C. ATP (adenosine triphosphate) 1. When food is burned a. Some of the energy is lost as heat (not useful) b. Some of the energy is stored in molecules of ATP ready to use energy a. Main molecule plus a phosphate tail
- 2. Structure of ATP a. Main molecule plus a phosphate tail b. Phosphates are negative repel eachother unstable c. ATP ADP (di = two) + phosphate (Bond brokenenergy RELEASED) d. ADP + phosphate ATP (Bond formedenergy STORED) Photosynthesis A. Plants convert the energy ofsunlight into the energy stored inglucose (chemical energy) B. Early Experiments in Photosynthesis
1. Jan Van Helmont a. Found the mass of a pot of soil... planted a seedlingallowed plant to grow for 5 yearsmass of soil was unchanged b. Van Helmont said mass came from H2O (incorrect conclusion) c. Mass actually comes from CO2 2. Joseph Priestly Experiment with glass jar, candle, plant & mouse a. What is being produced by the plant? Oxygen! C. Photosynthesis Overview
1. Reactants: carbon dioxide & water 2. Another requirement: sunlight 3. Products: glucose (a monosaccharide) and oxygen 4. Equation: (with sunlight) 6CO2 + 6H2O C6H12O6 + 6O2 5. Photosynthesis also requires pigments colored substances that absorb light energy so it can be used for photosynthesis a. Chlorophyll absorbs red and blue light best; reflects green (thats why plants are green!) b. Carotenoids absorbs different colors than chlorophyll; reflects yellow and orange (fall colors!) D. The Light Reactions (Also called the Light-Dependent Reactions)
1. Energy in light is captured by pigments & (with the help of H2O) is used to make ATP 2. NADPH (another energy molecule) is also made both ATP & NADPH will be used in the dark reactions 3. Occurs in the thylakoids of chloroplasts (chlorophyll is in here) 4. Oxygen produced as a waste product E. The Dark Reactions (Also called Light-Independent Reactions or Calvin Cycle)
1. Light is not needed 2. ATP, NADPH (from light rxns) and CO2 are used to make glucose 3. Called carbon fixation transfer of carbon from CO2 (inorganic) into glucose (organic) 4. Why called the Calvin Cycle? Named after the man who identified the reactions (Melvin Calvin Nobel Prize 1961) Cellular Respiration A. Organism gets food by eating or using photosynthesis to make glucose (which stores energy) B. Cellular respiration releases that energy by breaking down food and converting stored energy into ATP (ready to use!) C. Equation: C6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP D. Glycolysis (Always occurs before cellular respiration)
1. Takes place in the cytoplasm 2. Anaerobic no oxygen needed 3. What is the process? a. Using 2 ATP, glucose is broken in half 2 pyruvate molecules b. 4 ATP produced (net ATP = 2) E. Process of Cellular Respiration
1. Includes two steps: Krebs Cycle (Step 1) and Electron Transport (Step 2) 2. Takes place in mitochondria 3. Aerobic oxygen is needed 4. Cellular respiration starts out using the pyruvate formed in glycolysis - Pyruvate must move from cytoplasm into mitochondria 4. Events during Cellular Respiration a
4. Events during Cellular Respiration a. Pyruvate is broken down - Each time a bond is broken, the energy released is used to make ATP! b. Carbon dioxide and water are produced as waste products c. 34 ATP produced ( ATP from glycolysis = 36 ATP total) F. At the end ofcellularrespiration % of theenergy in glucosehas been used bycells (put into ATP) This is actually very efficientmuch more efficient than cars burning gasoline (14 26%) G. How do photosynthesis and cellular respiration relate?
1. Opposite processes Photosynthesis deposits money or energy Respiration withdraws money or energy So Whats going on? Fermentation A. Why is fermentation necessary? 1. Respiration requires what important gas? Oxygen 2. What happens when oxygen is not available? Fermentation 3. If oxygen is not required for fermentation, it isanaerobic 4. Fermentation does NOT make ATP, but it does allow glycolysis to continue (so we get at least 2 ATP) B. Lactic Acid Fermentation
1. Pyruvate from glycolysis is converted into lactic acid 2. Occurs in muscles during rapid exercise Body cannot supply enough oxygen to the muscle tissues to produce all of the ATP needed Lactic acid fermentation is used Buildup of lactic acid in musclesburning sensation C. Alcoholic Fermentation
1. Occurs in yeasts and a few other microorganisms 2. Pyruvate is broken down to produce alcohol and CO2 3. Important to bakers & brewers Putting it all together