Chloroplast membrane

Cell biology
Chloroplast
Components of a typical chloroplast

1 Granum
2 Chloroplast envelope   ◄ You are here

2.1 Outer membrane
2.2 Intermembrane space
2.3 Inner membrane

3 Thylakoid

3.1 Thylakoid space (lumen)
3.2 Thylakoid membrane

4 Stromal thylakoid
5 Stroma
6 Nucleoid (DNA ring)
7 Ribosome
8 Plastoglobulus
9 Starch granule


Chloroplasts contain several important membranes, vital for their function. Like mitochondria, chloroplasts have a double-membrane envelope, called the chloroplast envelope, but unlike mitochondria, chloroplasts also have internal membrane structures called thylakoids. Furthermore, one or two additional membranes may enclose chloroplasts in organisms that underwent secondary endosymbiosis, such as the euglenids and chlorarachniophytes.[1]

The chloroplasts come via endosymbiosis by engulfment of a photosynthetic cyanobacterium by the eukaryotic, already mitochondriate cell.[2] Over millions of years the endosymbiotic cyanobacterium evolved structurally and functionally, retaining its own DNA and the ability to divide by binary fission (not mitotically) but giving up its autonomy by the transfer of some of its genes to the nuclear genome.

  1. ^ Kim, E., and Archibald, J. M. (2009) "Diversity and Evolution of Plastids and Their Genomes". In The Chloroplast, Anna Stina Sandelius and Henrik Aronsson (eds.), 1–39. Plant Cell Monographs 13. Springer Berlin Heidelberg. doi:10.1007/978-3-540-68696-5_1 ISBN 978-3-540-68696-5
  2. ^ Ochoa de Alda, Jesús A. G.; Esteban, Rocío; Diago, María Luz; Houmard, Jean (15 September 2014). "The plastid ancestor originated among one of the major cyanobacterial lineages". Nature Communications. 5: 4937. Bibcode:2014NatCo...5.4937O. doi:10.1038/ncomms5937. PMID 25222494.