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Photosynthesis – Part I Spring 2013 - Althoff Reference: Mader & Windelspecht Ch. 7) Lec 07 • Photosynthetic Organisms • Process of Photosynthesis Definitions • Photosynthesis converts ____________ into the ________________ of a ________________ • ____________ = photosynthetic organisms that produce their _______________ examples: ________________ ________________ ________________ • Autotrophs = _______________ Plants Algae Cyanobacteria _________________ The opposite of AUTOTROPHS are… • _______________ = ____________ …they cannot make their own food…aka ____________________ carbohydrates. • Heterotrophs, as do autotrophs, use ___________________ produced by photosynthesis as a source of building blocks for growth and repair…as well as a source of chemical energy for __________ work. _________________ Fungi Insects Mussels Birds, Fish, Mammals, etc. Photosynthesis by product…. = ___ Value to all organisms • Carry on ____________ ____________ O2 bubbles from Elodea leaves Besides the O2 “byproduct” of photosynthesis…there are other benefits to humans: • • • • • Building materials (think lumber) Fabrics (think cotton) Paper Pharmaceuticals Aesthetic value (think flowers) Photosynthesis takes place in the “green” portions of plants (aka leaves) • For flowering plants (most of what is on earth), ____________ tissue is present that specializes in photosynthesis. mesophyll Entry of raw materials for photosynthesis…. mesophyll • CO2 in air enters through ________ • H2O in soil enters through _______, then up ________ ______ (aka vein) • CO2 and H2O, once in the leaf, ________ into _______________ Top of leaf Chloroplast Actual chloroplast ~37,000 x • ___________ ___________: outer and inner • __________ semifluid interior • __________ – flattened sacs • _______ (gramum pl.)– stacked thylakoids double membrane Chloroplast structure Grana close up…. thylakoid membrane thylakoid space independent thylakoid in a granum overlapping thylakoid in a granum Thylakoids • Spacing of thylakoids thought to be connected to the ____________________ thylakoids within a chloroplast…. • The result is a _________________ …providing a tremendous amount of surface area for photosynthesis to occur. Thylakoids and Stroma • The __________________ actually contains the chlorophyll…and other pigments capable of absorbing solar energy. • The ________ contains an energy-rich solution where CO2 is first attached to an organic compound…then reduced to a carbohydrate. Photosynthesis: The Process • The equation implies that photosynthesis involves ________ (=oxidationreduction)…and the movement of electrons from one molecule to another • This means a) CO2 gains an electron and b) H20 loses one….a ____ is “transferred” Photosynthesis: The Process • In photosynthesis, solar energy is used to generate the ___________________ the CO2 to a __________________. • Keep in mind, this carbohydrate represents the _______ produced by land plants, algae, and cyanobacteria that feeds _____ the biosphere. Two Important Coenzymes • ________ is the coenzyme of oxidationreduction active during photosynthesis. When reduced it accepts 2 electrons and and 1 hydrogen atom to become _______ • When NADPH oxidizes, it give up its electrons • NADP+ + 2e- + H+ NADPH Back to the Elodea leaf… • What molecule supplies the electrons that reduce NADP+ during photosynthesis? The _____________ _________________ that is split! Two Sets of Reactions • _________________—so named because they only occur when solar energy is available. Associated with “_______” energy • __________________________—named for Melvin Calvin who discovered the enzymatic reaction that reduces CO2. Associated with “____________” energy CALVIN CYCLE REACTIONS LIGHT REACTIONS O2 CH2O Light Reactions • Sunlight/solar energy __________ by chlorophyll that drives photosynthesis • Solar energy “________” the electrons that move down an _________ _______________. As it does, energy released is captured as _____ molecules. Mader Fig. 6.12 p114 Light Reactions To summarize…. • Solar energy _________________ (ATP, NADPH) • But, O2 is given off, too O2 Calvin Cycle • Enzymes present speed up the reduction of CO2 during __________________ • Occurs in the ____________________ of the chloroplast stroma • When reduction results in carbohydrate…it can later be converted to glucose…this is achieved by using ATP and NADPH _____ the light reactions Calvin Cycle Reactions To summarize…. • _________ energy __________ energy (ATP, NADPH) (carbohydrate) CH2O