STUDY GUIDE PHOTOSYNTHESIS CHAPTER 8 BS161 Section 3 Dr Osteryoung Spring 2015 The exam will cover the material emphasized in class and in the lecture notes Answer the questions in Review of Concepts 8 1 8 3 Answer the multiple choice end of chapter quiz questions for Concepts 8 1 8 6 Also answer the Syn thesis questions for 8 1 8 5 and 8 6 Review the learning outcomes on the last slide of the lecture notes Where does the oxygen we breathe come from The oxygen we breathe comes from the products of photosynthesis When plants split water to re lease the 2 H needed for the photosystem the oxygen that is also released is released by the plant as a byproduct into the air What is the source of carbon for photosynthesis The source of carbon for plants is the CO2 in the air Explain in your own words the cycling of carbon and oxygen through the ecosystem How do photosyn thetic and non photosynthetic organisms contribute to these cycles O2 in the atmosphere is produced by photosynthesis by plants photosynthetic organisms and consumed by repiration and the CO2 in the air is produced by non photosynthetic organisms and consumed by photosynthesis Define heterotroph Define autotroph List several examples of each Explain why heterotrophs are de pendent on autotrophs Heterotrophs don t make their own food o Humans o Heterotrophs cannot make their own glucose so they eat autotrophs to get this glucose needed for cellular respiration Autotrophs make their own food o Plants Define photosynthesis Is it an endergonic or exergonic process Is it anabolic or catabolic Photosynthesis the process using light energy to convert CO2 to glucose o Endergonic and anabolic builds up macromolecules which involves putting bonds to gether which requires energy Photosynthesis can be divided into two main parts the Calvin cycle and the light reactions Explain what each contributes to the overall process of photosynthesis and how these two processes cooperate Diagram and label the parts of the chloroplast where the enzymes associated with the Calvin cycle and the light reactions are located The light reactions absorb the energy from the sun allowing the electrons to be excited and by do ing this the electrons phosphorylate ADP into ATP and reduces NADP to NADPH which is used during the Calvin cycle to dephosphorylate ATP and oxidize NADPH allowing the conver sion of CO2 to glucose G3P All of the following molecules participate in photosynthesis CO2 O2 H2O sugar NADP NADPH ATP ADP Pi Which are produced by the light reactions Which are consumed by the light reactions Which are produced by the Calvin cycle Which are consumed by the Calvin cycle Produced by Light reactions NADPH ATP O2 Consumed by Light Reactions NADP H2O Consumed by Calvin Cycle CO2 ATP NADPH Produced by the Calvin cycle sugar NADP ADP Pi Write an overall summary reaction for photosynthesis In what ways does the summary reaction reflect the actual process by which photosynthesis occurs in the cell In what ways does the summary reactions not reflect the actual process Answer these questions for respiration as well 6CO2 12H2O Light Energy C6H12O6 6H2O 6O2 It reflects that actually process because photosynthesis really uses CO2 H2O and light energy to function properly The CO2 is reduced to glucose and water is oxidized to oxygen The light en ergy comes from the sun However the problem arises with the extra water on the products side It is difficult to explain exactly how the extra water arose on the products side What are the goals of photosynthesis and respiration i e their overall biological significance to the organism Goals of Photosynthesis To reduce Carbon dioxide to glucose that allows the glucose to be used Goals for respiration To break down the covalent bond within the glucose molecule to provide for cellular respiration the energy ATP for cellular processes Explain the similarities and differences between these two processes in terms of the fate of carbon oxy gen electrons and energy Similarities between Photosynthesis and Respiration Electrons are used to synthesis ATP in the ETC energy is used for cellular processes Differences between Photosynthesis and Respiration In Photosynthesis carbon is reduced to glu cose CO2 makes glucose In respiration glucose 6 carbon molecule is decarboxylated into CO2 glucose makes CO2 Also in Photosynthesis Oxygen is by product of the splitting of water In respiration oxygen is the final electron acceptor Describe the role of the enzyme Rubisco in the Calvin cycle What kind of macromolecule is Rubisco What substrates would you predict bind to its active site based on Figure 8 17 What type of reaction does it catalyze The role of Rubisco is to connect the 6 molecule carbon to the RuBP 6 Carbon molecule creat ing a 12 carbon molecule PGA Substrates Ribulose 1 5 biphosphate 5C RuBP and CO2 Rubisco is an enzyme and an enzyme is a PROTEIN Rubisco catalyzes a carboxylation reaction it joins the the 5C RuBP molecule to 6molecules of CO2 by joining the two carbons from the end of the RuBP C to the carbons of CO2 through de carboxylation Diagram and describe in very general terms the three phases and alterations in carbon skeletons that oc cur during the Calvin cycle you do not have to memorize exact stoichiometries or structures What are the major inputs and outputs of the Calvin cycle Where do the major inputs and outputs come from and where do they go How many carbons does the sugar that exits the Calvin cycle have How is this related to the synthesis of glucose in the summary reaction 1 Carbon fixation converting CO2 and RuBP into PGA 2 Reduction PGA reduced to G3P and2 G3P molecules are put together to make glucose 3 Regeneration of RuBP G3P is phosphorylated to make RuBP Outputs 2 G3P 16 Pi 18 ADP 12 NADP The sugar that comes out of the Calvin Cycle is glucose which has 6 carbons 6 CO2 18 ATP 12NADPH 2 G3P 18 ADP 16 Pi 12 NADP Inputs 6 CO2 18 ATP 12 NADPH o This is related to the synthesis of glucose in the summary reaction because the Calvin cy cle must go through 6 rounds to produce 1 molecule of glucose How many molecules of CO2 must be fixed in the Calvin cycle for the net synthesis of one molecule of glucose hexose How many carboxylation reactions must be catalyzed by Rubisco for the net synthe sis of one molecule of hexose note that Rubisco attaches 1 molecule of CO2 to one molecule of RuBP at a time 6 molecules of CO2 must be fixed in the Calvin Cycle for 1 molecule of glucose to be produced 6