POWER

Chlorplast Structure

 

The color of a leaf comes from chlorophyll, the green pigment in the chloroplasts. Chlorophyll play an important role in the absorption of light energy during photosynthesis. Chloroplasts are also mainly found in the mesophyll cells that form the tissues in the interior of the leaf. Each chloroplast has two membranes around a central aqueous space, the stroma. In the stroma is an elaborate system of interconnected membranous sacs, the thylakoids. The interior of the thylakoids forms another compartment, the thylakoid space or lumen. Thylakoids may be stacked into columns called grana. Grana are connected within a chloroplast by stromal lamellae. Photosynthetic prokaryotes lack chloroplasts. Their photosynthetic membranes arise from infolded regions of the plasma membranes, folded in a manner similar to the thylakoid membranes of chloroplasts. 

 

Evidence that chloroplasts split water molecules enabled researchers to track atoms through photosynthesis. 

 

Chlorophyll molecules embedded in the thylakoid membrane absorb light energy. These molecules are the most important pigments for absorbing the light energy used in photosynthesis. A chlorophyll molecule has a hydrophobic "tail" that embeds the molecule into the thylakoid membrane. The "head" of the chlorophyll molecule is a ring called a porphyrin. The porphyrin, which has a magnesium atom at its center, is the part of the chlorophyll molecule that absorbs light energy.