Protists
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- They are eukaryotes because they all have a nucleus.
- Most have mitochondria although some have later lost theirs. Mitochondria were derived from aerobic alpha-proteobacteria that once lived within their cells.
- Many have chloroplasts with which they carry on photosynthesis. Chloroplasts were derived from photosynthetic cyanobacteria living within their cells.
- Many are unicellular and all groups (with one exception) contain some unicellular members.
- The name Protista means "the very first", and some of the 80-odd groups of organisms that we classify as protists may well have had long, independent evolutionary histories stretching as far back as 2 billion years. But genome analysis added to other criteria show that others are derived from more complex ancestors; that is, are not "primitive" at all.
- Genome analysis also shows that many of the groups placed in the Protista are not at all closely related to one another; that is, the protists do not represent a single clade.
- So we consider them here as a group more for our convenience than as a reflection of close kinship
- "Eukaryotes that are neither Animals, Fungi, nor Plants".