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Energy and Life 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 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 CO2 + H2O + Sunlight ----------- C6H12O6 + O2 Chlorophyll= pigment inside the chloroplast that absorbs sunlight Light Reactions= Convert light energy to ATP (during the day) Dark Reactions= Convert CO2 + H2O to sugars (at night) Light Reactions ● ● 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 ● ● 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 Cellular Respiration C6H12O6 + O2 ----------- CO2 + H2O + Energy The breakdown of food molecules to release energy needed for work. 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 2 ATP Step 4: Electron Transport Chain= Uses the coenzymes (NADH) to crank out mass amounts of ATP 32 ATP! Total ATP Production 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) Anaerobic Respiration Alcoholic Fermentation: Converts pyruvate (3carbon 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 Anaerobic Respiration Lactic Acid Fermentation: converts pyruvate to Lactic Acid ● 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 vs. Anaerobic Aerobic vs. 1. Oxygen required required 2. Produces 36 ATP Anaerobic Respiration 1. No Oxygen 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! Question: Where does the rest of the energy go? Answer: Lost as heat Organelles where these events occur... ● 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 ● 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 Enzymes & Catalysts Key Terms Catalyst: A chemical agent that accelerates a chemical reaction without being permanently changed in the process Enzyme: A protein molecule that acts as a Biological Catalyst Substrate: the molecule that the enzyme binds to; the molecule that undergoes the reaction 5 Things All Enzymes Have in Common 1. They don’t make anything happen that could not happen on its own 2. They are NOT permanently altered or used up by a reaction (they are re-used) 3. The same enzyme usually works for the forward and reverse directions of a reaction 4. All enzymes work on specific substrates 5. Enzymes function to lower the Activation Energy of a chemical reaction Activation Energy Activation Energy: The extra energy required to destabilize existing chemical bonds and initiate a chemical reaction Enzymes increase the rate of reactions by lowering the Activation Energy! Active Site: “Pocket” on the enzyme in which the substrate binds to forming an Enzyme-Substrate Complex (lock and key) Products: what the substrate is turned into after binding to the enzyme; gets released Factors That Affect Enzyme Activity 1. Temperature: rate increases with temp. increase only until the temperature optimum is reached; maximizes random molecular movement Optimal temp range for most human enzymes = 35-40 C (94-99 F ) 2. pH: pH optimum = pH 4 to 6; pepsin (a digestive enzyme) works best at pH 2 Factors That Affect Enzyme Activity 3. Ionic Concentration: high ion concentrations (salt) slow down enzyme activity 4. Cofactors & Coenzymes: presence of small non-protein molecules required for proper enzyme catalysis Cofactors = inorganic (Zn, Cu, metals) Coenzymes = organic (vitamins) Factors That Affect Enzyme Activity 5. Enzyme Inhibitors: substance that binds to an enzyme and decreases its activity Competitive Inhibition= resemble an enzymes normal substrate, compete with it for the active site, block it ● Noncompetitive Inhibition = binds to another part of the enzyme besides the active site; causes the enzyme to change shape so the active site can’t bind to the substrate ● 6. Allosteric Regulation: receptor site on some part of the enzyme other than the active site; serve as a chemical “on/off” switch (activator/inhibitor) 7. Feedback Inhibition: the product of one metabolic pathway can become the inhibitor for another