Biology 116 1st Edition Lecture 11Outline of Last Lecture I. Photosynthesis Part 2II. BiochemistryIII. Calvin CycleOutline of Current Lecture I. Photorespiration Current LectureBiochemistry Continued:Rubisco: catalyzes the first step in the Calvin Cycle, is the most abundant protein in the world, is made up of large subunits (encoded by chloroplasts) and small subunits (encoded by nucleus), has 8 active sitesPhotosynthesis part 3Photorespiration:Rubisco can catalyze two different reactions: Caroxylation: RuBP + CO2 => Cavlin Cycle OR Oxygenation: RuBP + CO2 =>3PGA + phosphoglycolate (Called Photorespiration, in this case Rubisco is an oxgenase) 3PGA: goes to the Calvin CyclePhosophoglycolate: goes to photorespiratory metabolism Photorespiratory metabolism is a cycle that involves three organelles: the chloroplast, the peroxisome, and the mitochondria Starts in chloroplast where photoglycolic acid and PGA converted to glycolic acid => to the peroxisome where it is converted to glycine => to the mitochondriawhere two molecules are converted to CO2 and NH3 , within this process NAD+ is converted to NADH ,then the rest is These 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.converted to serine => to the peroxisome where it is converted to hydroxy pyruvic acid which is then converted to glyceric acid, within this process NADH is converted to NAD+=> then in the chloroplast the glyceric acid is converted into PGA and then finally RuBP which reacts with O2 to produce phosphoglycolic acid, during this ATP is converted to ADP- This process adds O2 to RuBP and releases oxygen= respiration - This is more likely in hot and dry environments where CO2 levels are low O2 are high Photorespiration is a process in which some, but not all of the CO2 is lost by the plant. -Areas that are cool/ moist lead to less CO2 loss -C3 plants thrive in this environment (called C3 because they are produce a 3 carbon molecule at first) Why? : 1) the cool/ moist environment causes the stomata of a plant to open which increases the CO2diffusion from the atmosphere to the cholorplast which increases the CO2 to O2 ratio in the stroma2) CO2 in aqueous solution in the stroma are more soluble in lowertemperatures which increases the CO2 to O2 ratio in the stroma3) This higher CO2 to O2 ratio in the stroma leads to more carbolxylation which reduces the oxygenation which causes the photosynthetic rate to