Respiration vs. PhotosynthesisPhotosynthesis: Chapt. 8Joseph Priestley born 1733Jan Baptista van Helmont (1580–1644)PhotosynthesisPhotosynthetic EquationWhere does PS occur? Green leavesMore Specifically: The ChloroplastsChloroplast StructurePhotosynthesis: in two distinct reactionsPhotosynthesis: involves 2 separate pathwaysThe Light ReactionsA Closer look…Light Absorption: by ChlorophyllChlorophyllChlorophyll TypesAccessory PigmentsPhotosystemsSlide 19From the Photosystem, e- are passed along an Electron Transport Chain.. The Photosynthetic Electron Transport Chain (PETC)Slide 21Photosynthetic Electron Transfer Chain (PETC)Slide 23Slide 24Two Photosystems operate in light absorptionSo how does it all work?The Z SchemeSlide 28The Z Scheme:So what have we done?End Result of Light ReactionsSlide 32Light Reactions: ATP SynthesisPhotophosphorylationNoncyclic PhotophosphorylationCyclic PhotophosphorylationRemember…Photosynthesis occurs in two distinct reactionsThe Dark ReactionsDark Reactions: Calvin CycleAlong Calvin Cycle: Phosphoglycerate (3PG) transforms to: Glyceraldehyde 3- phosphate (G3P)Calvin CycleG3P = Glyceraldehyde 3-PhosphateHow does G3P make glucose?Calvin Cycle: SummationSlide 45RubiscoSlide 47Respiration vs. PhotosynthesisPhotosynthesis and respiration as complementary processes in the living world. Photosynthesis uses the energy of sunlight to produce sugars and other organic molecules. These molecules in turn serve as food. Respiration is a process that uses O2 and forms CO2 from the same carbon atoms that had been taken up as CO2 and converted into sugars by photosynthesis. In respiration, organisms obtain the energy that they need to survive. Photosynthesis preceded respiration on the earth for probably billions of years before enough O2 was released to create an atmosphere rich in oxygen. (The earth's atmosphere presently contains 20% O2.)Photosynthesis:Chapt. 8•The Early Years:–von Helmont (1600’s)–Priestley (1700’s)•From these studies it was concluded:–PS converts H20 & CO2 to organic matter & 02Joseph Priestleyborn 1733Also: Invented soda pop and the rubber eraser “The injury which is continually done to the atmosphere by the respiration of such a large number of animals...is, in part at least, repaired by the vegetable creation.” Priestley became the first person ever to observe photosynthesis in plants - the fact that they take in carbon dioxide and release oxygen. In 1772, Priestley placed a shoot of a green plant into a container of water. He then covered the container and lit a candle...The candle burned longer than without the plant. Priestley also was able to keep mice alive under the jar. Priestley had just discovered what would later be known as oxygen. He called the gas dephlogisticated air, based on the phlogiston theory (the idea that combustion was essentially the process of losing a hypothetical substance known as phlogiston) of the day.Jan Baptista van Helmont (1580–1644) Van Helmont describes his own experiment: “I took an earthen vessel, in which I put 200 pounds of earth that had dried in a furnace, which I moistened with rainwater, and I implanted therein the trunk or stem of a willow tree, weighing five pounds. And at length, five years being finished, the tree spring from thence did weigh 169 pounds and about three ounces. … Lest the dust that flew about should be mingled with the earth, I covered the lip or mouth of the vessel with an iron plate covered with tin and easily passable with many holes. … I again dried the earth up in the vessel, and there was found the same 200 pounds, wanting about two ounces. Therefore, 164 pounds of wood, bark, and roots, arose out of water only.”PhotosynthesisLife is powered by sunlight. The energy used by most living cells comes ultimately from the sun. Plants, algae, and some bacteria use energy from sunlight, particularly blue and red wavelengths, to build molecules which later can be split through cellular respiration to retrieve some of that energy. Storing energy in molecules and then oxidizing those molecules to retrieve the stored energy maintains all life on Earth. Plants are often called ‘producers’ because they produce energy-storing molecules used by almost all other organisms on Earth. By eating plants, herbivores and carnivores ‘steal’ these energy-storing molecules to maintain their own life processes. Ultimately, the process of photosynthesis is the most important chemical reaction on Earth.Photosynthetic Equation 6CO2 + 6H2O C6H12O6 + 6O2 six molecules of carbon dioxide plus six molecules of waterproduce one molecule of sugar plus six molecules of oxygenWhere does PS occur? Green leavesMore Specifically: The ChloroplastsChloroplast Structure•surrounded by double membrane •Contains additional internal membranes termed thylakoids which may be unstacked or stacked (grana)•internal region termed stroma •Text pg 69Photosynthesis:in two distinct reactionsLight Reactions–absorb light–produce oxygenDark Reactions–fix CO2Photosynthesis:involves 2 separate pathways•Light reactions.. light absorption, oxygen production, uses sunlight E to produce ATP & NADPH•Dark reactions..CO2 uptake and conversion to glucose (CO2 fixation). Contains cyclic pathway to fix CO2The Light Reactions•requires light input (light absorption)•produces oxygen, NADPH & ATP •occur on thylakoid membranesA Closer look…Light Absorption:by ChlorophyllEvidence: Light absorption spectrum of chlorophyll matches the effective light wavelengths for rates of photosynthesis Text pgs. 140-141Chlorophyll•lipid molecule with a porphyrin ring structure and a long HC tail•HC tail embeds chlorophyll in lipid bilayer of thylakoid•has a central Mg+ atom•Text pg. 141Chlorophyll Typesa in all photosynthetic eukaryotes and cyanobacteriab in higher plants & green algaec in brown algae, diatoms & dinoflagellatesa & ca & ba & ba & ca & cAccessory Pigments•Increase efficiency of photosynthesis by absorbing light of different wavelengths and passing e- on to Chlorophyll•Most common... the carotenoids: lipids which absorb in blue/green light and thus reflect in red/yellow. •Add to Fall colors •Text pg 140PhotosystemsChlorophylls & accessory pigments group together to form a cohesive unit: a Photosystem of two components:1. Light-harvesting component: gathers light E. and passes it around2. Reaction center: Specific Chl a molecule which passes