Photosynthesis overview

Photosynthesis, the food making process of plants, uses light energy in order to create sugar or starch from water (H2O) and carbon dioxide (CO2).  The chemical equation of the said reaction is:

Energy + 6CO2 + 6H2O ---> C6H12O6 + 6O2

The process of photosynthesis in eukaryotes occurs in the chloroplasts while photosynthetic prokaryotes do not have chloroplasts. Chloroplast, the green pigment in plants, contain numerous membranous disk-like structures that are known as thylakoids and they are stacked together to form larger structures, known as grana (granum singular) that looks like stacks of coins. The molecules that have the ability to absorb light energy (photoreceptors) are found in the thylakoid membranes.

Stroma Function

Most of the enzymes essential in the process of photosynthesis are normally embedded in the stroma and in the thylakoid membranes. The stroma is the fluid-filled space that is surrounding the grana, and is also involved in the synthesis of organic molecules from water and carbon dioxide. After the thylakoids, the process of producing starch or sugar moves out to the stroma. It is where enzymes take the carbon from carbon dioxide and then mixes it with oxygen and hydrogen to make a simple carbohydrate molecule. This stroma function is generally known as either the light independent reactions or the dark reactions.

©2005-2015 Plant Biology Advice - Dean Ravenscroft