Study Guide Ch 10 (Photosynthesis)

Chapter 10 Terms 1. Autotrophs  An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms  Autotrophs use energy from the sun or from oxidation of inorganic substances to make organic molecules from inorganic ones 2. Heterotrophs  An organism that obtains organic food molecules by eating other organisms or substances derived from them 3. Chlorophyll  A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes  Chlorophyll a participates directly in the light reactions, which convert solar energy a to chemical energy 4. Mesophyll   Leaf cells specialized for photosynthesis In C3 and CAM plants, mesophyll cells are located between the upper and lower epidermis  In C4 plants, they are located between the bundle-sheath cells and the epidermis 5. Stomata  Openings of the leaf that lets CO2 in and out 6. Thylakoid  A flattened, membranous sac inside a chloroplast  Often exist in sacks called grana that are interconnected  Their membranes contain molecular “machinery” used to convert light energy to chemical energy 7. Stroma  The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA  Involved in the synthesis of organic molecules from carbon dioxide and water 8. Light reactions   The first two major stages in photosynthesis (preceding the Calvin cycle) These reactions, which occur on the thylakoid membranes of the chloroplast or on the membranes of certain prokaryotes, convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process 9. Photosystem I  A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes  There are two types of photosystems, I and II  They absorb light best at different wavelengths  Prefers wavelengths at 700 nm 10. Photosystem II  One of two light-capturing units in a chloroplast’s thylakoid membrane of in the membrane of some prokaryotes; it has two molecules of P680 chlorophyll a at its reaction center  Prefers wavelengths at 680 nm 11. NADP+/NADPH  Nicotinamide adenine dinucleotide phosphate  An electron acceptor that, as NADPH, temporarily stores energized electrons produced during the light reactions 12. Calvin cycle  The second of two major stages in photosynthesis (following the light reactions)  Involves fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate 13. Photophosphorylation  The process of regenerating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis 14. Carbon fixation  The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote) 15. CO2 reduction  Carbon dioxide is reduced to carbon monoxide or hydrocarbons by the enrgy of incident light 16. RuBP regeneration  Ribulose bisphosphate is consumed in the carboxylation step of carbon fixation  If such fixation is to continue, RuBP must be regenerated 17. Glyceraldehyde 3-phosphate  A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis 18. Photorespiration  A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output  Photorespiration generally occurs on hot, dry, bright days, when stroma close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco 19. C3 plants  A plant that uses the Calvin cycle for the initial steps that incorporate CO 2 into organic material, forming a three-carbon compound as the first stable intermediate  Need a wet climate 20. C4 plants  A plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle   Prefer warm, dry climate Stomata is open during the day, bringing in CO2 and the stomata closes at night 21. CAM plants  A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions  In this process, carbon dioxide entering open stroma during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when the stroma is closed  Prefer dark, warm, dry environments  Stomata closes during the day, so the stomata bring in CO2 during the night Chapter 9 &10 1. Using a drawing, compare and contrast mitochondria and chloroplast structure and functions. Photosynthesis - Photo = light reactions - Synthesis = Calvin cycle - 6CO2 + 12H2O + ATP  C6H12O6 + 6O2 + 6H2O