BBMB 405 1St Edition Exam 1 Study Guide Lectures 1 11 Special Notes If a question has an N after that question wasn t assigned In terms of studying for exam Don t just go over this study guide Review all reaction schemes and go over past exams I would focus on past exams because I heard Beitz repeats questions from old exams Chapter 19 Review Questions Lecture 1 2 1 Complementary powers Photosystem I produces powerful reductant whereas photosystem II produces a powerful oxidant Identify the reductant and oxidant and describe their roles a PS1 reductant reduced ferrodoxin converts NADP into NADPH b PS2 oxidant Plastoquinone Q able to be reduced and convert ADP to ATP 2 If a little is good What is advantage of having extensive set of thylakoid membranes in chloroplasts Everything happens in membrane so more membrane the better A Thylakoid is inside chloroplasts and is a membrane bound compartment and is the site where light dependent reactions of photosynthesis takes place The thylakoid lumen is surrounded by extensive set of thylakoid membranes The thylakoid membranes in chloroplasts increase the amount of surface area This increases photosynthesis which increases number of ATP and NADH generating sites 3 N 4 One thing leads to another What is the ultimate electron acceptor in photosynthesis The ultimate electron donor What powers the electron flow between the donor and the acceptor a NADP b Water c Light energy harvested by photosynthetic reaction centers powers electron flow between H2O electron donor and NADP electron acceptor 5 N 6 N 7 N 8 What fraction of energy of 700 nm absorbed by photosystem I is trapped as high energy electrons the energy not trapped as high energy electrons is released as heat A In PSI the reaction center is P700 which releases an electron to flow to ferredoxin Ferrodoxin NADP reductase then catalyzes the construction of NADPH delta G 0 nF delta E 0 delta G 0 is usuable energy of reaction n number of moles of substance F is Faraday s constant 96 48 kJ mol 1V 1 E 0 is electrical potential of reaction For one mole of electrons PSI has E 0 of 1V therefor delta G 0 nFE 0 1mol x 96 48 kJ mol 1V 1 x 1V delta G 0 96 48 kJ Photons of blue light have the energy of 172 kJ so 96 48 kJ 172 kJ 56 9 10 11 12 N N N Weed killer 1 Dichlorophenyldimethylurea DCMU a herbicide interferes with photophosphorylation and oxygen evolution However it does not block oxygen evolution in the presence of an artificial electron acceptor such as ferricyanide Propose a site for inhibitory action of DCMU A The formation of NADPH from NADP is catalyzed by ferredoxin NADP reductase catalyze Those electrons are replenished by PS2 When electrons are excited in P680 chlorophyll they transfer electrons to plastocyanin which then transfers electrons back to PS1 PS2 extracts electrons from water molecules Dichlorophenyl dimethyl urea DCMU inhibits electron transfer between PS1 and PS2 which prevents creation of proton gradient This effect can be countered by adding artificial electron carrier to accept electrons in absence of plastocyanin 13 N 14 Infrared harvest Consider relation between energy of photon and its wavelength a Some bacteria are able to harvest 1000 nm light What is energy in kilojoules or kilocalories of mole also called an Einstein of 1000 nm photons A 120 kJ Einstein 1 b What is maximum increase in redox potential that can be induced by 1000 nm photon A 1 24 V c What is minimum number of 1000 nm photons needed to form ATP from ADP and Pi Assume delta G of 50 kJ mol 1 12 kcal mol 1 for the phosphorylation reaction A One 1000 nm photon has free energy content of 2 4 molecules of ATP so the minimum number of photons needed to drive synthesis of one ATP molecules would be 0 42 photons 15 N 16 N 17 Functional equivalents What structural feature of mitochondria corresponds to thylakoid membranes Membrane that allows for charge separation A Thylakoid membrane is like the cristae of mitochondria internal compartment formed by inner membrane Electron transport chain occurs in this region There is maximum surface area for chemical reaction that happens in mitochondria This is similar to function of thylakoid membrane within chloroplast 18 Compare and contrast Compare and contrast oxidative phosphorylation and photosynthesis a The metabolic pathway oxidative phosphorylation uses energy released by oxidation of nutrients to generate ATP Electrons are transferred from donors to acceptors to release energy These reactions take place in intermembrane wall of mitochondria The electrons flow through electron transport chain and are used to generate proton gradient This proton gradient can be used to operate ATP synthase that drives ATP synthesis b Photosynthesis is used by plants to convert light energy into chemical energy Photosysnthesis consumes carbon dioxide and water then is able to releases oxygen Light energy is harvested by photosynthetic reaction centers in chloroplasts That energy converted to ATP and stored c Similarities both of these processes take place in specialized organelles mitochondria and chloroplast both generate ATP both utilize electron transport that occurs within these specialized organelles both can generate proton gradients that are used to drive generation of ATP d Differences oxidative phosphorylation NADH is utilized while in photosynthesis NADPH is utilized Chapter 20 Review Questions Lecture 3 5 Dark Reactions 1 A vital cycle Why is Calvin cycle crucial to functioning of all life forms A Calvin cycle generates hexoses from carbon dioxide and water Hexoses are sugars used to provide energy in the form of ATP Intermediates generated by process can be converted to ribose and deoxyribose that are needed for nucleic acids 2 Compare and contrast Identify similarities and differences between Krebs cycle and Calvin cycle A Aerobic organisms use the Krebs cycle to create energy Oxidation of acetate is derived from carbohydrates fats and proteins which results in carbon dioxide Important for generating NADH and FADH2 Calvin cycle is for light independent carbon fixation Converts carbon dioxide and water into organic compounds using energy from electronically excited carriers Similarities Both utilize carbon chemistry Calvin cycle photosynthesis Krebs cycle oxidative phosphorylation Both require high energy electrons Calvin cycle NADPH Krebs cycle NADH both regenerate starting material Differences Calvin cycle takes place in stroma and Krebs cycle takes place is matrix