BOLOGY 107 Lecture 15Outline of Last Lecture I. Light Reactionsa. Linear electron flowb. Geometry of the reactionc. ATP production II. Calvin Cyclea. Phases Outline of Current Lecture III. Alternatives to the Calvin Cyclea. C3 plantsb. C4 plantsc. Arid conditions IV. Cellular Respirationa. Productive cyclesCurrent LectureAlternatives to the Calvin Cycle1) C3 plantsa) Rubisco initially fixes CO2 into a 3-C sugar in the Calvin Cyclei) Rice, wheat, soybeans2) C4 plantsa) CO2 is initially fixed into a 4-C sugar in the mesophyll cells called oxaloacetateb) 4-C sugar passed to bundle-sheath cells where CO2 is passed to RuBP to enter Calvin Cyclei) Sugarcane, corn, grass3) Arid conditionsa) Stomata stay closed during the day to save wateri) O2 builds up and CO2 is depletedb) Goes through photorespirationi) Rubisco uses O2 instead of CO2(1) Produces CO2(2) Uses ATP, produces no sugar, produces ammonia(3) Sends ammonia to mitochondria and peroxisomes to convert it to CO2 and waterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c) CAM plants i) Temporal separation of C fixation from Calvin Cycle(1) Open stomata during cool nights to fix CO2 with minimal water lossCellular Respirationd) Why do we breathe if O2 is extremely cytotoxic?i) It is the ultimate electron acceptor, the reduction is highly exergonic4) Productive cyclesa) Glycolysis, “sugar-splitting”i) Ten enzyme-mediated steps(1) Kinase- an enzyme type that adds phosphates(2) Isomerase- an enzyme type that creates isomers(3) Dehydrogenase- an enzyme type that removes hydrogenii) All intermediates are phosphorylatediii) Invest 2 ATP(1) Add phosphate to glucose(2) Change it to fructose(3) Add phosphate to fructose(4) Fructose splits to 2 G3Psiv) Total yield: 2 pyruvate, 2 ATP, 2 NADPH, and 2
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