Editing Chloroplast (section)

===== Apicomplexans =====
[[File:Plasmodium.png|thumb|Diagram of Plasmodium, including its apicoplast.]]

[[Apicomplexans]] are a group of alveolates. Like the [[helicosproidia]], they're parasitic, and have a nonphotosynthetic chloroplast.<ref name="Keeling-2010" /> They were once thought to be related to the helicosproidia, but it is now known that the helicosproida are green algae rather than part of the CASH lineage.<ref name="Keeling-2010" /> The apicomplexans include ''[[Plasmodium]]'', the [[malaria]] parasite. Many apicomplexans keep a [[vestigial]] red algal derived chloroplast<ref name="Nair-2011" /><ref name="Keeling-2010" /> called an [[apicoplast]], which they inherited from their ancestors. Apicoplasts have lost all photosynthetic function, and contain no photosynthetic pigments or true thylakoids. They are bounded by four membranes, but the membranes are not connected to the [[endoplasmic reticulum]].<ref name="Kim-2009" /> Other apicomplexans like ''[[Cryptosporidium]]'' have lost the chloroplast completely.<ref name="Nair-2011" /> Apicomplexans store their energy in [[amylopectin]] granules that are located in their cytoplasm, even though they are nonphotosynthetic.<ref name="Kim-2009" />

The fact that apicomplexans still keep their nonphotosynthetic chloroplast around demonstrates how the chloroplast carries out important functions other than [[photosynthesis]]. [[Plant]] chloroplasts provide plant cells with many important things besides sugar, and apicoplasts are no different—they synthesize [[fatty acid]]s, [[isopentenyl pyrophosphate]], [[iron-sulfur clusters]], and carry out part of the [[heme]] pathway.<ref name="Nair-2011" /> The most important apicoplast function is [[isopentenyl pyrophosphate]] synthesis—in fact, apicomplexans die when something interferes with this apicoplast function, and when apicomplexans are grown in an isopentenyl pyrophosphate-rich medium, they dump the organelle.<ref name="Nair-2011" />