Week 9 Notes
Week 9 Notes Bio 208
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This 5 page Class Notes was uploaded by Kylie McLaughlin on Monday October 26, 2015. The Class Notes belongs to Bio 208 at Northern Illinois University taught by Dr. Ed Draper in Fall 2015. Since its upload, it has received 18 views. For similar materials see Fundamentals of Cell Biology in Biological Sciences at Northern Illinois University.
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Date Created: 10/26/15
Week 9 Notes Chapter 10 cont there are 8 steps in linear electron ow 1 Photon hits a pigment and its energy is passed among pigment molecules until it excites P680 2 An excited electron from P680 is transferred to the primary electron acceptor now called P680 3 H20 is split by enzymes and the electrons are transferred from the hydrogen atoms to P680 thus reducing it to P680 a P680 is the strongest known biological oxidizing agent b 02 is released as a byproduct of this reaction 4 Each electron quotfallsquot down an electron transport chain from the primary electron acceptor of PSll to PSl 5 Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane a Diffusion of H protons across the membrane drives ATP synthesis 6 ln PSl like PSll transferred light energy excites P700 which loses an electron to an electron acceptor a P700 P700 that is missing an electron accepts an electron passed down from PSll via the electron transport chain 7 Each electron quotfallsquot down an electron transport chain from the primary electron acceptor of PSl to the protein ferredoxin Fd 8 The electrons are then transferred to NADP and reduce it to NADPH a Electrons of NADPH are available for the reactions of the calvin cycle b This process also removes an H from the stroma in electrons cycle back from Fd to the PSl reaction center cycic reaction flow uses only photosystem 1 and produces ATP but not NADPH no oxygen is released this is pathway used in some bacteria in organisms that contain both photosystems eukaryotes and cyanobacteria cyclic electron ow may protect cells from lightinduced damage ight reactions occur in PSl PSll ETC makes ATP and produces NADPH Comparison of Chemiosmosis in Chloroplasts and Mitochondria mitochondria and chloroplasts use an ETC to make a proton gradient in mitochondria protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix in chloroplasts protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma ATP and NADPH are produced on the side facing the stroma where the calvin cycle takes place quotknobsquot of ATP synthase face the quotcytosolquot is made by chemiosmosis as protons return to the quotcytosolquot 1 Light reactions a Occur in thylakoids b Pigments chlorophylls carotenoids absorb light energy c ATP is made chemiosmosis photophosphorylation d NADPH reducing power is made electrons needed to reduce NADP come from H20 water is split e 02 is a waste product f Light reactions generate ATP and increase the potential energy of electrons by moving them from H20 to NADPH 2 Calvin cycle a quotdark reactionquot or quotlight independent reactionsquot b Uses soluble enzymes in stroma c quotcarbon xationquot reduction C02 gt gt gt sugars ex Glucose d Uses ATP and NADPH made in the light reactions e ADP and NADP products are returned to the light reactions Calvin Cycle Uses the Chemical Energy of ATP and NADPH to Reduce C02 to Sugar calvin cycle like the citric acid cycle regenerates its starting material after molecules enter and leave the cycle cyce builds sugar from smaller molecules by using ATP and the reducing power of electrons carried by NADPH carbon enters the cycle as C02 and leaves as a sugar named for net synthesis of 1 G3P the cycle must take place three times xing 3 molecules of C02 calvin cycle has three phases 1 Carbon xation catalyzed by RuBlSCO is ribulose bisphosphate carboxylase oxygenase a 3C02 3C 3RuBP 15C gtRuBSCO gt 3C6 cpd 18C gt 6PGA 18C 2 Energy input and reduction a 6PGA 18C gt 6ATP gt 6bPG 18C gt 6NADPH gt 6G3P 18C b lG3P 3C yield of calvin cycle per 3C02 3 Regeneration of the C02 acceptor RuBP a SG3P 15C gt3ATP gt 3 RuBP 15C b Energy costs of calvin cycle 3C02 gt9ATP 6NADPH gt lG3P 3C c Glucose synthesis gluconeogenesis ZG3P 6C gt gt gt 1 glucose 6C d No additional energy is needed so 18 ATP and 12 NADPH per glucose Light Reactions are carried out by molecules in the thylakoid membranes convert light energy to the chemical energy of ATP and NADPH spit H20 and release 02 to the atmosphere Calvin Cycle Reactions take place in the stroma use ATP and NADPH to convert C02 to the sugar G3P return ADP inorganic phosphate and NADP to the light reactions Chapter 12 The Cell Cvcle in unicellular organisms division of one cell reproduces the entire organism multicelluar eukaryotes depend on cell division for deveop from fertilized egg growth repair Binarv Fission in Bacteria prokaryotes bacteria and archaea reproduce by a type of cell division called binary ssion in binary ssion the chromosome replicates beginning at the and the two daughter chromosomes actively move apart the plasma membrane pinches inward dividing the cell into two mitochondria and chloroplasts within eukaryotic cells divide in a similar way Eukarvotic Cell Cvcle the cell cycle consists of mitotic M phase mitosis and cytokinesis interphase cell growth copying of chromosomes in preparation for cell division entire cycle takes about 24 hours in proliferating mammalian cells Mphase about 1 hour Gl gtS gtGZ gtM gtGl sometimes a cell will temporarily or permanently leave the cell cycle and enter a GO stage these cells are quiescent cells cell cycle control system the cell cycle control system is regulated by both internal and external controls checkpoints speci c conditions must be met for the cycle to progress to the next phase 1 61 entry into S a Cell big enough b Enough nutrients 2 62 entry into M a DNA replication done b DNA repaired 3 M begin anaphase a All chromosomes at metaphase plate ces address such questions using Cellular Organization of the Genetic Material Genome can consist of a single DNA molecule common in prokaryotic cells or a number of DNA molecules common in eukaryotic cells eukaryotic chromosomes consist of heterochromatin euchromatin chromosomes are condensed only during mitosis in 61 each chromosome consists of one in 62 after 5 each chromosome consists of 2 sister chromatids which are held together by a centromere mitosis will separate sister chromatids so each daughter cell gets one rue one chromosome contains one centromere eukaryotic cell cycle 2n6 6 chromosomes each with 2 sister chromatids chromosome condensation chromosome alignment 6 condensed chromosomes prepared from cells in metaphase when chromosomes are most highly condensed identify chromosomes by 1 Size 2 Banding patterns 3 Position of the centromere a diploid cell has two almost identical chromosomes which are called homologous or a homologous pair you have one homologue of each type from your mother and the other from your father
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