The activities are controlled by the aggregating behaviour of the subunits and the co-operative interactions of membranes on top of each other. They contain an enzyme system, that transfers galactosyl subunits from uridine diphosphate galactose onto diglycerides. The resulting monogalactosyl diglycerides and digalactosyl diglycerides are incorporated into the chloroplast membranes and are a typical feature. Moreover do the two outer membranes contain the xanthophyll violaxanthin that lends them a slightly yellowish colour. Chloroplast envelopes that have been exposed to strong light become more orange due to a conversion of violaxanthin to zeaxanthin.
Chloroplasts contain genetic information .
40 additional enzymes are needed for the synthesis of chlorophyll and carotenoids and again 40 enzymes take part in the other activities of photosynthesis. As far as the figures go could the chloroplast DNA contain just enough genes for all these enzymes. But the list of the chloroplast activities is not finished yet. Furthermore are enzymes for lipid and amino acid syntheses, enzymes for the carbohydrate metabolism and Enzyme enzymes for the synthesis of a number of secondary plant products . The list shows that quite some enzymes have to be imported from the cytosol into the chloroplasts.