Ultimately, photosynthesis stores chemical energy by using the excited chlorophyll molecule in the reaction center as a reducing agent to reduce a stable electron acceptor (Figure 8.8). Ground-state chlorophyll (symbolized Chl) is not much of a reducing agent, but excited chlorophyll (Chl*) is a good one. To understand the reducing capability of Chl*, recall that in an excited molecule, one of the electrons is zipping around in an orbital farther away from its nucleus. Less tightly held, this electron can be passed
8.8 Energy Transfer and Electron Transport Rather than being lost as fluorescence, energy from a photon may be transferred from one pigment molecule to another, preserving the energy for biochemical work. In an antenna system, an excited pigment molecule can transfer energy through a series of other pigment molecules to a chlorophyll molecule in the reaction center. That molecule may become sufficiently excited that it gives up its excited electron, which can then be passed on to an electron carrier.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.