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Photosynthesis and Cellular Respiration Energy = the ability to do work Autotrophs = use sunlight, CO2 , and water to make their own food (sugars) PHOTOSYNTHESIS Heterotrophs = can’t make their own food, they have to eat autotrophs to stay alive! ATP = (Adenosine Tri-Phosphate) the energy storage molecule used by most organisms It is the usable version of a cells energy ATP gets broken down to release energy in the Mitochondria PHOTOSYNTHESIS Process of converting energy from sunlight to energy in chemical bonds: CO2 + H2O + Sunlight ----------- C6H12O6 + O2 Chlorophyll = pigment inside the chloroplast that absorbs sunlight Light absorbed by pigments gets incorporated into electrons Energized electrons are unstable and re-emit the absorbed energy Energy gets reabsorbed by electrons of a nearby pigment molecule This absorption re-emission cycle continues Light Reactions = (Photophosphorylation) Convert light energy to ATP (during the day); takes the energy in light and the electrons in water to make the energy rich molecules ATP and NADPH H20 + ADP + Pi + NADP+ + light ATP + NADPH + O2 + H Dark Reactions = (Calvin – Benson Cycle) Convert CO2 + H2O to sugars (at night); takes CO2 from the atmosphere and the energy in ATP & NADPH to create a glucose molecule. 6CO2+18ATP+12NADPH +H+ 18ADP+18 Pi +12NADP+ +1 glucose 1 CELLULAR RESPIRATION C6H12O6 + O2 ----------- CO2 + H2O + Energy The breakdown of food molecules to release energy needed for work, occurs in the Mitochondria. Step 1: Glycolysis = converts glucose (6-carbon sugar) to pyruvate (2, 3-carbon sugars) & releases energy 2 ATP Step 2: Aerobic Respiration = breakdown of Pyruvate in the presence of Oxygen NO ATP made! Step 3: Krebs Cycle = Produces coenzymes (NADH) to speed up the last step, CO2 given off (exhale) 2 ATP Step 4: Electron Transport Chain = Uses the coenzymes (NADH) to crank out mass amounts of ATP 32 ATP! Q. How many ATP are made from the energy released from the breakdown of 1 glucose? A. CELLULAR RESPIRATION PRODUCES A TOTAL OF 36 ATP MOLECULES! Anaerobic Respiration: Chemical reactions that release the energy from foods in the absence of oxygen (O2) Cells (active muscle cells) or organisms (bacteria, yeast) that use this process to get their energy needs live on the small amount of ATP that is provided by Glycolysis (2 ATP) 1. Alcoholic Fermentation: Converts pyruvate (3-carbon sugar) to CO2 and ethanol (alcohol) Bakers use the fermentation of yeast cells to make breads ( the CO2 makes the dough rise) Also used industrially in the manufacturing of beer & wine Ethanol is added to gasoline to make gasohol Occurs in plants, fungi, and bacteria 2 2. Lactic Acid Fermentation: converts pyruvate to Lactic Acid (Lactate) During strenuous exercise you deplete your muscle cells of oxygen so they enter the anaerobic cycle Lactic acid is a waste product produced from this Lactic acid build up in the muscles causes muscle cramping Lactic acid made in the muscles diffuses into the bloodstream , then goes to the liver, where it is converted back into pyruvate Aerobic 1. Oxygen required 2. Produces 36 ATP vs. Anaerobic Respiration 1. No Oxygen required 2. Produces 2 ATP ATP provided through the complete Aerobic breakdown of glucose provides energy for activities such as: eating, sleeping, exercising, & STUDYING BIOLOGY! Aerobic Respiration is relatively inefficient !! 36 ATP is only about half the energy contained in a glucose molecule! Q: Where does the rest of the energy go? A: Lost as heat 3 ORGANELLES Photosynthesis: Occurs in the Chloroplasts Both the Light and Dark reactions Stroma = fluid inside chloroplast (Dark reactions) Thylakoids = individual membrane layer (“pancake”); (Light reactions) Granum (Grana) = an entire stack of thylakoids Insert fig 3-2 Cellular Respiration: Occurs in the Mitochondria, Cytoplasm Glycolysis = occurs in the cytoplasm, products get shipped to the Mitochondria Aerobic Respiration + Krebs Cycle = occurs in the Mitochondria Matrix Electron Transport Chain = occurs on the Cristae Insert fig 4-2 4