Photosynthesis

Photosynthesis - Photosynthesis ~or~ What on Earth is Going...

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Photosynthesis ~or~ What on Earth is Going On Here, Anyway? I. Net Reaction: Energy (light) + 6CO 2 + 12H 2 O ---- Glucose (C 6 H 12 O 6 ) + 6H 2 O + 6O 2 II. Photosynthesis is the net chemical reduction of carbon dioxide to glucose. Reduction is the chemical opposite of oxidation. A. A molecule can be reduced in three different ways 1. It can lose oxygen atoms, or 2. It can gain hydrogen atoms, or 3. It can gain electrons. B. Reduction processes are generally constructive and endergonic . III. Photosynthesis has two parts, the Calvin Cycle (light-independent reactions) and the Light Reaction (light- dependent reaction). The Calvin Cycle is the process which actually accomplishes the primary task of photosynthesis (reduction of carbon dioxide), but requires the ATP and hydrogens provided by the Light Reaction to perform that task. Both parts of photosynthesis occur in the chloroplast. A. The Calvin Cycle occurs in the stroma of the chloroplasts. 1. The Calvin cycle is a series of reactions which accomplish the fixation of carbon dioxide and its reduction to carbohydrate. Each Calvin Cycle fixes one CO 2 and produces one sixth of a glucose molecule. Of course, the process doesn’t really produce one sixth of a molecule; it takes six coordinated Calvin Cycles to produce one whole glucose. 2. This is accomplished in a complicated series of reactions, some of which require energy (ATP) and some of which require “reducing power” (hydrogens). These are, of course, supplied by the Light Reaction. 3. While none of the reactions of the Calvin Cycle directly require light, they are dependent upon the ATP and NADP red provided by the Light Reaction, which is directly light dependent. Thus, the Calvin Cycle, like the Light Reaction, occurs only in the light.
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Photosynthesis - Photosynthesis ~or~ What on Earth is Going...

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