The chloroplast genome: a review

Chloroplasts are the metabolically active, semi-autonomous organelles found in plants, algae and cyanobacteria. Their main function is to carry out the photosynthesis process involving a conversion of light energy into the energy of chemical bonds used for the synthesis of organic compounds. The Chloroplasts' proteome consists of several thousand proteins that, besides photosynthesis, participate in the biosynthesis of fatty acids, amino acids, hormones, vitamins, nucleotides and secondary metabolites. Most of the chloroplast proteins are nuclear-encoded. During the course of evolution, many genes of the ancestral chloroplasts have been transferred from the chloroplast genome into the cell nucleus. However, these proteins which are essential for the photosynthesis have been retained in the chloroplast genome. This review aims to provide a relatively comprehensive summary of the knowledge in the field of the chloroplast genome arrangement and the chloroplast genes expression process based on a widely used model in plant genetic research, namely Arabidopsis thaliana.