Protists

• Mostly unicellular eukaryotes
• How did the Mitochondria and plastids arise?

  Endosymbiosis: Symbiotic relationship where one organism lives inside the other.
• Primary endosymbiosis: Original internalization (engulfs) of prokaryotes by an ancestral eukaryotic cell, resulting in the formation of the mitochondria and chloroplasts.
• Secondary endosymbiosis: A further step to gain the ability to photosynthesize. Engulfed by red algae, green algae. Creating a membrane , then it gets engulfed again creating two membranes.
• Diatoms: Gain ability to photosynthesize from green algae.
• First eukaryote would have been categorized as a protist.
• Protist obtain energy and materials in diverse ways :

  Some nutritional pathways are similar to the non-protist eukaryotic groups. 

  Ingestive heterotrophs (animal-like)

  Absorptive Heterotrophs 

  Photoautotrophs (plant-like)