Carbohydrates are organic compounds synthesized in the chlorophyll containing cells of some bacteria,-algae and green plant cells, during photosynthesis. Certain photoautotrophic bacteria eg. Green sulphur bacteria and purple sulphur bacteria contain pigments like chlorobium chlorophyll and bacteriochlorophyll respectively that helps them in photosynthesis. During photosynthesis carbon dioxide is reduced into carbohydrates by water and oxygen is liberated.