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Chloroplasts, organelles in the cells of certain eukaryotic organisms, house the molecular apparatus for photosynthesis. Bacteria-sized structures, somewhat football-shaped, a few micrometers in size, choroplasts number up to several hundred in cells with high photosynthetic rates, each a separate compartmented structure whose boundary consists of two membranes, the interior of the inner membrane containing a semiliquid matrix, called stroma, suspending a system of membranes, called thylakoids, their membranes embedding molecules of chlorophyll and other pigments that absorb energy from sunlight, the initiating step of the physico-chemical process of photosynthesis.[1] [2] [3] [4] [5]

(CC) Diagram: Emmanuel Boutet
Schematic of a chloroplast: 1. outer membrane; 2. intermembrane space; 3. inner membrane (1+2+3: envelope); 4. [stroma (aqueous fluid); 5. thylakoid lumen (inside of thylakoid); 6. thylakoid membrane; 7. granum (stack of thylakoids); 8. thylakoid (lamella); 9. Starch; 10. Ribosome; 11. plastidial DNA; 12. plastoglobule (drop of lipids).

The domain Eukarya includes chloroplast-containing, photosynthesis-capable organisms in two of its four kingdoms,[6] namely plantae (the plant kingdom) and protista (the protist kingdom), the former including photosynthesis-capable algae, mostly single-celled or colonizing members of the plant kingdom, and the green plants we see all around us, the latter, the protista, including diatoms, dinoflagellates, euglenids, and other members of the protist kingdom, a mixed group of mostly single-celled organisms.

Online images of chloroplasts

The Internet has numerous images of chloroplasts, the following of particular interest. Right click these links and open in new tab in order to save the current tab to this page for rapid return:

References and footnotes cited in text as superscripts

  1. Hall DO, Rao KK. (1999) Photosynthesis. 6th ed. Cambridge University Press. ISBN 0-521-64257-4. | Google Books preview.
  2. Blankenship RE (2002) Molecular Mechanisms of Photosynthesis. Wiley-Blackwell. ISBN 0632043210; ISBN 978-0632043217
  3. Cooper GM, Hausman RE. (2009) Chloroplasts and Other Plastids. In: The Cell: A Molecular Approach Fifth Edition, pp. 452-459. Sinauer Associates, Inc.
  4. Stern KR, Bidlack JE, Jansky S. (2008) Plastids. In: Introductory Plant Biology. 11th ed. pp. 41-42. Boston: McGraw-Hill Higher Education. ISBN 9780072830675.
  5. Hoober JK. (2000) Chloroplast structure and development. In: Photosynthesis: A Comprehensive Treatise. A.S. Raghavendra,editor. Cambridge University Press. ISBN 9780521784443. | Google Books preview, pp. 3-19. | Table of Contents. | Twenty-six chapters covering a broad range of topics in photosynthesis.
  6. Note:  See Kingdom (biology) for a more detailed discussion of the taxonomy of kingdoms in eukarya.