BIO 107 1nd Edition Exam 2 Study Guide Lectures 11 20 Week 4 Lectures 11 Cell Metabolism What are the first two laws of thermodynimics First law of thermodynamics Energy is never created or destroyed just tranfered Second law of thermodynamics Overall disorder in a closed system will decrease as useful energy is transferred to useless energy What is ATP Adenosine triphosphate ATP is the molecule used most in biological systems for energy It is used to phosphoylate a molecule then the phosphate is removed to release a large amount of energy Week 5 Lectures 12 13 Cell Metabolism cont What are enzymes and how are they used Enzymes are macromolecules usually proteins which act as a catalyst for reactions to lower the activation energy of a reaction They are not consumed in the reaction They are also substrate specific only working with a specific substrate no other How are enzymes regulated Competitive inhibition inhibitor binds to active site for the substrate so the substrate cannot bind It is overcome by adding more substrate Noncompetitive inhibition inhibitor binds to another site on the enzyme and changes the shape of the active site so the substrate cannot bind It cannot be overcome Feedback inhibition excessive amounts of the product from the reaction blocks the substrate by competitive inhibition What are redox reactions Redox reactions consist of the transfer on electrons in a reaction The reduced reactant the one that receives electrons is the oxidizing agent The oxidized reactant the one that loses electrons is the reducing agent Biological Energetics What is photosynthesis Photosynthesis is the process that plants with chloroplasts go through to create ATP from light and CO2 There are two processes that happen to create the ATP the light reaction and the Calvin Cycle The pigments chlorophyll a and b absorb light while a range of pigments called carotenoids absorb harmful light Week 6 Lectures 14 15 Biological energetics cont What is the light reaction The light reaction occurs in the thylakoid membrane and forms ATP NADPH and O 2 Electrons are excited in PSII and are passed to the quinone in the center These electrons are passed down the electron transport chain while electrons are stripped from H2O molecules to replace the ones that are passed This created free H ions and O2 gas The H ions are passed across the membrane to be later used to create ATP The electrons in the transport chain are passed to the PSI replacing the electrons that are removed due to excitation by light The newly removed electrons are passed to ferredoxin and then passed through another transport chain to reduce NADP to NADPH How is ATP created in this process A proton gradient is created in the membrane from the electron chain ATP synthase facilitates the diffusion of protons out using that energy to convert ADP and P to ATP What is the Calvin Cycle The Calvin Cycle occurs in stroma and produces glyceraldehydes 3 phosphate G3P by using ATP NADPH and CO2 First CO2 is attached to RuBP by rubisco and a 6 C sugar chain is made This molecule is highly unstable so it splits into 2 3 C sugars spontaneously The sugar is phosphorylated by ATP and then reduced NADPH to form G3P Through a full cycle 6 G3P are made One leaves the cycle to be used for larger sugar molecules the others are rearranged to form 3 5 C sugars which are then phosphorylated to recreate RuBP What are the alternatives to the Calvin Cycle C3 plants rubisco fixes CO2 into a 3 C sugar to start C4 plants CO2 is fixed to a 4 C sugar then passed to bundle sheath cells that then continue the Calvin Cycle Arid conditions no gas exchange occurs during the day O2 is used to produce ATP and ammonia which is then used to create water and CO2 CAM plants stomata is only opened on cool nights to conserve water Cellular Respiration What are the three types of enzymes involved in cellular respiration Kinase an enzyme that adds a phosphate Isomerase an enzyme that changes the molecule to another isomer Dehydrogenase an enzyme that removes a hydrogen What are the four steps of cellular respiration The steps within cellular respiration are glycolysis pyruvate oxidation citric acid cycle and oxidative phosphorylation Through the whole process 30 32 ATP are produced What is the investment phase of glycolysis The investment phase of glycolysis is when a phosphate is added to glucose and it is converted to fructose A second phosphate is added and the fructose is split into 2 G3Ps Week 7 Lectures 16 18 Cellular Respiration cont What is the payoff phase of glycolysis NAD takes an electron from G3P making NADH and a phosphate replaces a hydrogen atom on G3P The phosphate is removed to make ATP and the remaining phosphate on the G3P is move to a different location A water molecule is removed and another phosphate is transferred to an ADP to end with pyruvate and ATP What is pyruvate oxidation The pyruvate is transported into the first membrane of the mitochondria through facilitated diffusion and through the second membrane by active transport A CO2 is removed to end with acetate and the acetate is attached to Coenzyme A What is the citric acid cycle Citrate is created from acetyl CoA and oxaloacetate The water attached is moved to create and isomer Two electrons are transferred to NAD and two CO2 are removed CoA is re added and two hydrogen ions are removed to FADH2 Fumarate is the end product from that reaction and it is converted to malate with a water molecule Finally and electron is transferred to NAD and the cycle starts again What is oxidative phosphorylation Electrons are passed down to less energetic configurations and the energy is used to create a proton gradient NADH and FADH2 are stripped of electrons in the electron transport chain and the proton gradient is used to create ATP like in the Calvin Cycle Why does FADH2 supply less energy than NADH FADH2 enters the electron transport chain at a later point than NADH causing the electrons to not lose as much energy Anaerobic Respiration What is anaerobic respiration Anaerobic respiration is the creation of ATP without oxygen This is usually done by fermentation What are the two ways that fermentation can occur Lactic acid fermentation glycolysis occurs but no other steps in cellular respiration occur Instead NADH is used to convert the pyruvate to lactate only producing 2 ATP Alcohol fermentation the pyruvate is converted to acetaldehyde and then NADH is used to convert acetaldehyde to ethanol Only 2
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