Chloroplasts

Plants use energy from the sun in tiny energy factories called chloroplasts. Using chlorophyll in the process called photosynthesis, they convert the sun's energy into storable form in ordered sugar molecules such as glucose. In this way, carbon dioxide from the air and water from the soil in a more disordered state are combined to form the more ordered sugar molecules.

The simplified sketch of the chloroplast was made from an electron micrograph of a chloroplast from a higher order plant (Levy). Inside the chloroplasts are stacks of discs called thylakoids. They are compared to stacks of coins within the walls of the chloroplast, and they act to trap the energy from sunlight. The stacks of thylakoids are called grana. They are connected with an extensive sytem of tubules. The membranes of the grana contain smaller granules or particles called quantasomes which are composed to the pigments and other molecules which perform photosynthesis.

Order can be produced with an expenditure of energy, and the order associated with life on the earth is produced with the aid of energy from the sun.

Chloroplast Structure

Plants use energy from the sun in tiny energy factories called chloroplasts. The green color of leaves is attributable largely to these chloroplasts because they contain chlorophyll for photosynthesis. Though obviously oversimplified, the illustration depicts the somewhat elongated sausage type shape with large dimension 5-10 μmand smaller dimension 3-4 μm. Moore suggests 40-200 chloroplasts per photosynthetic cell and about 500,000 per square millimeter of leaf area.

There are two membranes, and inside the inner membrane is the gelatanous matrix called the stroma. The stroma contains ribosomes, DNA, and is the location for biochemical synthesis. Membranous sacs called thylakoids are arranged in stacks called grana. The chlorophyll in the thylakoid membranes carries out photosynthesis.