Biology 203 1st Edition Lecture 23 Outline of Last Lecture I. How do plants capture light?II. LeavesIII. RootsIV. Properties of WaterV. How does water get to the tops of trees?VI. Vascular Tissue: PhloemOutline of Current Lecture I. Photosynthesis vs. RespirationII. Where does photosynthesis occur?III. Light ReactionsIV. PhotolysisCurrent LectureI. Photosynthesis vs. Respirationa. Photosynthesis – storing energy and material in chemical bondsb. Respiration – releasing energy from chemical bonds to do useful workc. The chemical products of photosynthesis are the reactants of respiration, and vice versad. Photosynthesis consists of two sets of reactionsi. Light dependent reactions – produce high energy molecules (ATP and NADPH) to be used for making glucose in the light-independent reactionsII. Where does photosynthesis occur?a. Within the mesophyll cells, in the chloroplastsb. Inside the chloroplasti. An inner and outer membraneii. Stroma – the fluid inside the chloroplastiii. Thylakoid – organelle where photosynthesis occursiv. Granum – stack of thylakoidsv. Thylakoid space – the space inside the thylakoidc. Across different lineages of photosynthetic organisms, chloroplasts come in manyshapes, sizes and colorsd. Plastids have the same membranes and compartments as cyanobacteria and each compartment has a distinct set of proteins and functionsIII. Light ReactionsThese 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.a. Photosystemi. In the light reactions, light is absorbed by pigments organized into photosystemsii. The photosystem is embedded in the thylakoid membraneb. Light energy is transformed into chemical energy. Electrons flow from water to NADP+ and ATP is producedc. Electron flow in the thylakoid membrane results in NADPH and ATP production IV. Photolysisa. “Light-breaking” of wateri. 2 H2O 4e- + 4H+ + O2b. Revolutionary in earth’s history: sudden increase in oxygen killed most types of organisms alive at that timec. Occurs on inside-facing side of thylakoid membrane so H+ produced contribute to gradient for ATP productiond. One electron per photon, so 4 photons per molecule of oxygen
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