Chloroplasts are primarily responsible for a process called photosynthesis. This remarkable process allows plants, algae, and some bacteria to convert light energy, usually from the sun, into chemical energy stored in glucose.
During photosynthesis, chloroplasts utilize sunlight to transform carbon dioxide from the air and water from the soil into glucose and oxygen. The overall equation for photosynthesis can be summarized as:
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
Photosynthesis occurs in two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle). In the light-dependent reactions, chlorophyll and other pigments absorb sunlight and convert it into energy rich molecules like ATP and NADPH, while splitting water molecules to release oxygen as a byproduct. The subsequent Calvin cycle takes place in the stroma of the chloroplast, where ATP and NADPH produced in the first stage are used to convert carbon dioxide into glucose.
In essence, chloroplasts play a vital role in sustaining life on Earth by providing the oxygen we breathe and the organic compounds that form the basis of the food chain.