Chloroplast, which is a double-membrane-bounded organelle, is the main site for CO2 fixation via photosynthesis in green plants. The double-membrane configuration can regulate the transport of substances into and out of the chloroplasts with the aid of functional units like lipid bilayer and transmembrane proteins. Chloroplast, which is a double-membrane-bounded organelle, is the main site for CO2 fixation via photosynthesis in green plants. The double-membrane configuration can regulate the transport of substances into and out of the chloroplasts with the aid of functional units like lipid bilayer and transmembrane proteins. Bio & Medicine Nanomaterials Phys.org – latest science and technology news stories