Chloroplast Evolution
Mitochondria also had a similar origin, but chloroplasts are found only in plants and protista. In green plants, chloroplasts are surrounded by two lipid-bilayer membranes. They are thought to correspond to the outer and inner membranes of the ancestral cyanobacterium. Chloroplasts have their own genome, which is much smaller than that of free-living cyanobacteria. The DNA which remains shows clear similarities with the cyanobacterial genome. Many of the missing genes are encoded in the nuclear genome of the host.