Several hundred chlorophyll molecules occur as an organized array within a cluster of several transmembrane proteins.Thylakoid membraneComplex of several transmembrane proteinsChlorophyll moleculeThe Location of Chlorophyll Molecules Within Thylakoid Membranes*
Chlorophyll MoleculeSpace-fillingmodel(different kinds of atoms are shown in different colors)Chemicalstructure*The ring structure (head) of chlorophyll is polar and projects from the hydrophobic interior of thylakoid membranes. It is the portion of the molecule that absorbs light energy. The magnesium ion is required for its function.The tail of chlorophyll is nonpolar. It anchors the chlorophyll in place within transmembrane proteins by hydrophobic bonding.tailheadTextbook Fig. 10.10,p. 188Mg2+
has intentionally blurred sections.
Sign up to view the full version.
Light Harvesting in a Thylakoid Membrane1. A photon of light is absorbed by any one of the chlorophyll molecules within an array.2. The energy content of the light is transferred rapidly among the chlorophyll molecules within the array.3. The energy eventually becomes "trapped" in a special pair of chlorophyll molecules.4. Energized special-pair chlorophyll loses an electron to another molecule called a primary electron acceptor. This is an oxidation-reduction reaction.*Energytransfer among chlorophyll molecules does not involve any chemical reaction. Electrontransfer from the special pair” chlorophyll molecules to the primary electron acceptor is the first chemical reaction of photosynthesis.Textbook Fig. 10.12, p. 189