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  1. Key Points. Light energy splits water and extracts electrons in photosystem II (PSII); then electrons are moved from PSII to cytochrome b6f to photosystem I (PSI) and reduce in energy. Electrons are re-energized in PSI and those high energy electrons reduce NADP + to NADPH.

    • Step 1: Excitation of Photosystems with Light Energy and Photolysis of Water
    • Step 2: Generation of ATP by Electron Transport Chain
    • Step 3: Formation of NADPH
    • Alternative Pathway
    • Chemical Equation
    • Fate of The Products

    The function of the light-dependent reaction is to convert light energy into chemical energy within a multi-protein complex called the photosystem, found in the thylakoid membranes. There are two types of photosystems found in most plants: photosystem I (PSI) and photosystem II (PSII). Each photosystem is made of two components: 1) antenna complex ...

    The electrons released from photosystem II enter a chain of proteins known as electron transport chain (ETC). They move from PSII to a small lipid-soluble molecule, plastoquinone (Pq), and then to a protein complex called cytochrome b6f. The electrons are finally transferred to a copper-containing protein called plastocyanin (Pc) before being accep...

    This stage is the final step of the light-dependent reaction during which high energy electrons released from PSI travel a short second leg of the electron transport chain. Here, the electrons are first transferred to an iron-containing protein called ferredoxin (Fd) and then to a reducing agent, NADP, to form NADPH. This type of electron transport...

    Sometimes plants follow an alternative path of electron transport called cyclic photophosphorylation. This term is named so because electrons released from PSI move along a circular path before returning to the same photosystem. Cyclic photophosphorylation does not involve PSII and produces only the ATP, stopping the production of NADPH.

    2H2O + 2NADP+ + 3ADP + 3Pi → O2+ 2NADPH + 3ATP Reactants 1. H2O 2. NADP 3. ADP + Pi End Products 1. O2 2. NADPH 3. ATP

    The energy-carrier molecules, ATP, and NADPH produced in the light reaction are used in the second phase of photosynthesis or the Calvin cycle to assemble sugar molecules.

  2. Create a model that describes how light energy is transformed into chemical energy in the light-dependent reactions in C3 photosynthesis. Key terms your model should include: chloroplast, thylakoid, stroma, pigments, PSII, PSI, H20, O2, electrons, sunlight, H+, ATP synthase, ADP/ATP, NADP+/NADPH, reduction, and oxidation.

  3. The reactions that make up the process of photosynthesis can be divided into light-dependent reactions, which take place in the thylakoids, and light-independent reactions (also known as dark reactions or the Calvin cycle), which take place in the stroma.

  4. Jul 19, 2021 · The light-dependent reactions are depicted in Figure \(\PageIndex{7}\). Protein complexes and pigment molecules work together to produce NADPH and ATP. Figure \(\PageIndex{7}\): A photosystem consists of a light-harvesting complex and a reaction center.

  5. Sep 21, 2021 · In the light-dependent reactions, energy absorbed by sunlight is stored by two types of energy-carrier molecules: ATP and NADPH. The energy that these molecules carry is stored in a bond that holds a single atom to the molecule. For ATP, it is a phosphate atom, and for NADPH, it is a hydrogen atom.

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  7. Light reaction is the first stage of photosynthesis process in which solar energy is converted into chemical energy in the form of ATP and NADPH. The protein complexes and the pigment molecules help in the production of NADPH and ATP.