Editing Chloroplast (section)

=== Pyrenoids ===
{{main|Pyrenoid}}

The chloroplasts of some [[hornworts]]<ref>{{cite journal |doi=10.1071/PP01210 |year=2002 |last1=Hanson |first1=David |last2=Andrews |first2=T. John |last3=Badger |first3=Murray R. | name-list-style=vanc |journal=Functional Plant Biology |volume=29 |issue=3 |pages=407–16 |title=Variability of the pyrenoid-based CO<sub>2</sub> concentrating mechanism in hornworts (Anthocerotophyta)|pmid=32689485 |bibcode=2002FunPB..29..407H }}</ref> and algae contain structures called [[pyrenoid]]s. They are not found in higher plants.<ref name="Ma-2011">{{cite journal | vauthors=Ma Y, Pollock SV, Xiao Y, Cunnusamy K, Moroney JV | title=Identification of a novel gene, CIA6, required for normal pyrenoid formation in Chlamydomonas reinhardtii | journal=Plant Physiology | volume=156 | issue=2 | pages=884–96 | date=June 2011 | pmid=21527423 | pmc=3177283 | doi=10.1104/pp.111.173922 }}</ref> Pyrenoids are roughly spherical and highly refractive bodies which are a site of starch accumulation in plants that contain them. They consist of a matrix opaque to electrons, surrounded by two hemispherical starch plates. The starch is accumulated as the pyrenoids mature.<ref name="Retallack-1970" /> In algae with [[Photosynthesis#Carbon concentrating mechanisms|carbon concentrating mechanisms]], the enzyme [[RuBisCO]] is found in the pyrenoids. Starch can also accumulate around the pyrenoids when CO<sub>2</sub> is scarce.<ref name="Ma-2011" /> Pyrenoids can divide to form new pyrenoids, or be produced [[De novo synthesis|"de novo"]].<ref name="Retallack-1970">{{cite journal | vauthors=Retallack B, Butler RD | title=The development and structure of pyrenoids in Bulbochaete hiloensis | journal=Journal of Cell Science | volume=6 | issue=1 | pages=229–41 | date=January 1970 | doi=10.1242/jcs.6.1.229 | pmid=5417694 }}</ref><ref name="Brown-1970">{{cite journal|last1=Brown|first1=Malcolm R| first2=Howard J | last2=Arnott | name-list-style=vanc |title=Structure and Function of the Algal Pyrenoid|journal=Journal of Phycology|year=1970|url=http://www.botany.utexas.edu/mbrown/papers/hreso/h26.pdf|access-date=31 December 2012|doi=10.1111/j.1529-8817.1970.tb02350.x|volume=6|pages=14–22|s2cid=85604422|url-status=dead|archive-url=https://web.archive.org/web/20130531182224/http://www.botany.utexas.edu/mbrown/papers/hreso/h26.pdf|archive-date=31 May 2013}}</ref>

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