BIOL 120 1st Edition Exam 3 Study Guide Lectures 13 15 Energy Energy the capacity to do work flows into the biological world from the sun Laws of Thermodynamics o Energy cannot be created or destroyed it can only change from one form to another o Entropy disorder is continuously increasing energy transformations occurring spontaneously to get matter from less stable to more stable and vice versa Metabolism It is the total of all chemical reactions carried out by an organism Anabolic making o Expend energy to synthesis molecules Catabolic breaking down o Harvest energy by breaking down molecules Biochemical pathways o Reactions occur in a sequence product of one reaction is the substrate for the next Feedback inhibition o Shutting down enzyme activity by binding the end product of a pathway to the first sight because enough material is already present Turns back on once more is needed Cellular Energy ATP main source of cellular energy NADH secondary source of energy o NAD H 2e NADH reversible reaction Redox reactions o o o Reduced an atom or molecule gaining an electron Oxidized an atom or molecule losing an electron Oxidation and reduction events are always coupled Cellular Respiration STEPS o Glycolysis involves the initial oxidation and partial breakdown of Glucose Glucose 6C to Pyruvic Acid 3C occurs in the cytoplasm It is a series of 10 reactions Potential energy released is used to form ATP All enzymes needed are found in the cytosol Energy payoff phase 6C is split into two pyruvates 2 molecules of NAD form NADH 4 molecules of ATP made and a net gain of 2 o Pyruvate processing pyruvate is oxidized to form acetyl CoA In the presence of O2 pyruvate produces acetyl CoA and NADH and CO2 o Citric Acid Cycle Acetyl CoA is oxidized to two CO2 molecules Released potential energy is used to reduce NAD to NADH reduce FAD to FADH2 Phosphorylate GDP to GTP later become ATP Completes glucose oxidation for one glucose the citric acid cycle has to run twice producing 6 NADH 2 FADH and 2 ATP o Electron Transport Chain and chemiosmosis compounds that were reduced in steps 1 3 are oxidized in reactions leading to ATP production occurs in inner mitochondrial membrane O2 is the final electron acceptor Oxidative phosphorylation the energy released during this process is used to pump protons H across the plasma membrane into intermembrane space protons move through enzyme ATP synthase Oxidative Phosphorylation This mode of ATP production links the phosphorylation of ADP with NADH and FADH2 oxidation Chemiosmosis ETC pumps protons from mitochondrial matrix into intermembrane space used to make ATP ATP Synthase Structure A structure that protons flow through that catalyzes the phosphorylation of ADP to ATP Energy Yield Theoretical 36 ATP Actual 30 ATP per glucose Fuels for ATP o First use carbs then fats and proteins as a last resort Aerobic vs Anaerobic Aerobic uses oxygen to produce ATP more productive Anaerobic does not use oxygen to produce ATP o Lactic Acid fermentation occurs in muscle cells Makes 2 ATP molecules o Alcohol fermentation occurs in yeast Makes 2 ATP Photosynthesis Conversion of light energy into chemical energy Stages o Light dependent Requires light Makes ATP and NADPH Occurs in thylakoid membrane Chlorophyll a and b green colors Carotenoids red orange and yellow pigments Photosystem I absorbs light at 700nm Photosystem II absorbs light at 680 nm Energy decreases as electrons are donated and the process repeats with added light energy o Light independent reaction Uses ATP and NADPH to synthesis CO2 Photosystems Photosystem a complex formed from chlorophyll molecules working together in groups Antenna Complex light harvesting complex o Captures photons and channels them to reaction center chlorophylls Reaction Center o Transmembrane protein o When a chlorophyll absorbs a photon of light an electron is excited to a higher energy level Photosystem II o Has a core of ten transmembrane protein subunits o Has 2 P680 chlorophyll o Reaction center contains 4 manganese atoms needed for oxidation of water o Has b6 f complex Proton pump embedded in thylakoid membrane Photosystem I o Reaction center has 12 14 protein subunits o Has two P700 chlorophyll o Accepts electrons to make NADP into NADPH Chemiosmosis o Used to synthesis ATP o Calvin Cycle catalyze the reaction of carbon fixation Types of photophosphorylation Non cyclic electrons flow in a non cyclic manner Energy gets lost and system is not constant need a constant supply of electrons to replace lost energy o Also known as Z pathways o Electrons come from photolysis of water o Generates NADPH oxygen and ATP o Uses both Photosystem I and II o Energy level of protons goes up and then transferred to electron acceptor because it is too much and keeps being transferred until I energy slowly decreasing until reaches I and process continues o Has 4 steps Primary photoevent Photon of light is captured by a pigment molecule Charge separation Energy is transferred to the reaction center and an excited electron goes to an acceptor Electron Transport Electrons move through carriers and reduce NADP to NADPH Chemiosmosis Makes ATP Cyclic electron flow stays constant with energy being received and removed simultaneously o Only uses photosystem II o Generates ATP through the electron transport chain doesn t make oxygen Calvin Cycle Also called C3 pathways of photosynthesis Key step is attachment of CO2 to RuBP to form PGA Uses rubisco to react with carbon and oxygen o Carboxylase fixing carbon o Oxygenase fixing oxygen Light reaction provides ATP to run Calvin Cycle which makes glucose fixes CO2 and regenerates RuBP 3 Phases o Carbon Fixation RuBP 5C CO2 PGA 3C o Reduction PGA is reduced to G3P which is used to synthesis glucose Extra sugar created is stored as starch o Regeneration of RuBP Photorespiration Carboxylation favored under normal conditions Photorespiration oxygenase favored when stoma are closed in hot conditions Stomata o Openings in leaves that control gas exchange o CO2 concentration is low during photosynthesis et Co2 in Needed because the Calvin Cycle is constantly using up CO2 Other types of Photosynthesis C3 pathway o Plants that fix carbon using the Calvin Cycle o Uses Rubisco enzyme o Affinity for CO2 and O2 C4 Pathway o adds CO2 to PEP to form 4 carbon molecules o Uses PEP carboxylase o affinity for CO2C3 o Spatial solution o Occurs in mesophyll cell and Bundle sheath cells PEP carboxylase fixes CO2 in mesophyll making it