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Photosynthesis and Plant Biochemistry Fundamentals

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Figures (10)

The internal structure of a chloroplast
Overview of the Calvin cycle and carbon fixation
Calvin cycle step 1 (black circles represent carbon atoms)
Regeneration stage of the Calvin cycle
The regeneration stage of Calvin's cycle. Substances and their parts are outlined in colors: green - carbon accepting aldoses, pink - ketoses-donors of three-carbon groups, yellow - parts of ketoses remaining after donation of two-carbon keto-groups highlighted in orange. Enzymes are also highlighted: aldolases in purple and transketolases in red.
Simplified C3 cycle with structural formulas
The overall equation of the Calvin cycle (black circles represent carbon atoms)
Schematic of photosynthesis in plants. The carbohydrates produced are stored in or used by the plant.
Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar.
Chloroplast ultrastructure:outer membraneintermembrane spaceinner membrane (1+2+3: envelope)stroma (aqueous fluid)thylakoid lumen (inside of thylakoid)thylakoid membranegranum (stack of thylakoids)thylakoid (lamella)starchribosomeplastidial DNAplastoglobule (drop of lipids)

Key Points

  • Plant cells, in turn, have three genomes, and chloroplast genome is usually also inherited maternally.
  • The thylakoid itself is enclosed by the thylakoid membrane, and within the enclosed volume is a lumen or thylakoid space.
  • In most cases, the lower epidermis contains more stomata than the upper epidermis because the bottom of the leaf is cooler and transpiration there is safer.
  • Palisade mesophyll is located in the upper layer and serves to decrease the intensity of sunlight for the spongy mesophyll, and also catches slanted sun rays.
  • The excited electrons lost from the reaction center (P700) of photosystem I are replaced by transfer from plastocyanin, whose electrons come from electron transport through photosystem II.
  • The reactions of the Calvin cycle are closely coupled to the thylakoid electron transport chain, as the energy required to reduce the carbon dioxide is provided by NADPH produced during the light dependent reactions.

Terms

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