Fundamentals of Microbiology

1.3.1.3 Chloroplasts

All photosynthetic eukaryotic organisms, including microscopic algae possess chlorophyll containing organelles called chloroplasts. The structure of chloroplast reveals thylakoids. The thylakoid membrane is impermeable to ions and other metabolites and well suited for its role in protein translocation and the generation of proton motive force for the synthesis of ATP. The thylakoids are stacked to produce structural units called grana. The stroma of chloroplasts contains enzymes for reduction of CO₂ to organic material. The outer chloroplast membrane is highly permeable and allows ATP and glucose synthesised during photosynthesis to diffuse into the cytoplasm.  

Although some bacteria are photosynthetic, they do not possess chloroplasts. Instead, components of the photosynthetic mechanism are located on membranous structures formed by modification of the cytoplasmic membrane.