NOTES: CH 10, part 1: Photosynthesis in Nature 10.1 – Photosynthesis converts light energy to the chemical energy of food. ● PHOTOSYNTHESIS = & the conversion of this energy to (in the form of sugar) -AUTOTROPHS: “ ”; PHOTOAUTOTROPHS: to synthesize food (e.g. plants) ● Photosynthesis occurs in , , certain other , and some ● These organisms feed not only themselves but also the entire living world…thank you plants! ● HETEROTROPHS: “ ”; -animals that eat plants or other animals ● Almost all heterotrophs, including humans, depend on photoautotrophs **some heterotrophs are: -decomposers: Chloroplasts: The Sites of Photosynthesis in Plants ● ● Their green color is from CHLOROPHYLL, the ● Light energy absorbed by chlorophyll drives the synthesis of organic molecules in the chloroplast ● Through microscopic pores called STOMATA, CHLOROPLASTS: ● ● found primarily in leaves ( ) ● contain green pigment (absorbs light energy) ● found mainly in mesophyll ( ) ● a typical mesophyll cell has ● CO2 enters and O2 leaves through ● water is delivered to leaves CHLOROPLAST: (sketch a chloroplast): ● enclosed by 2 membranes ● STROMA = ● THYLAKOID MEMBRANES are interconnected & contain the thylakoid space, or lumen (are usually in stacked columns called ) ● chlorophyll is stored in the thylakoid membranes STROMA = THYLAKOID MEMBRANES are interconnected & contain the thylakoid space, or lumen (are usually in stacked columns called ) chlorophyll is stored in the thylakoid membranes PATHWAYS OF PHOTOSYNTHESIS TOTAL equation for photosynthesis: 6CO2 + 12H2O + light energy C6H12O6 + 6O2 + 6H2O NET EQUATION: The Splitting of Water ● Chloroplasts hydrogen into sugar molecules , incorporating the electrons of Tracking Atoms Through Photosynthesis: (draw in arrows to track the atoms) Reactants: 6CO2 + 12H2O Products: C6H12O6 + 6H2O + 6O2 Photosynthesis as a Redox Process ● Photosynthesis is a redox process in which and *like respiration, photosynthesis is a series of redox reactions…BUT, the electron flow is reversed!…the electrons increase in potential energy as they move from water sugar …an uphill process! (the required energy boost comes from light energy) Two Stages of Photosynthesis: 1) (a.k.a. the “dark reactions” or light-independent reactions) 2) ● Photosynthesis consists of the light reactions (the photo part) and the Calvin cycle (the synthesis part) LIGHT REACTIONS: ● ● light is absorbed by chlorophyll and drives a transfer of electrons and H from water to an acceptor called: ● water is split and ● NADP+ as a “waste product” is reduced to NADPH…ALSO, ATP is generated via phosphorylation of ADP ( CALVIN CYCLE: ● CO2 from air is incorporated into organic molecules by ● NADPH and ATP from the light reactions power the production of sugar ● also called: “ ” Locations of the Photosynthesis Reactions: ● Light reactions occur in the ● Calvin cycle occurs in the or !)