1. CHAPTER 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists
Modules – 16.21

2. Cell with nucleus and endomembrane system
PROTISTS…the eukaryotes
The eukaryotic cell probably originated as a community of prokaryotes—The Endosymbiotic Theory of Lynn Margulis (1970)
Eukaryotic cells evolved from prokaryotic cells more than 2 billion years ago
The nucleus and endomembrane system of eukaryotes probably evolved from infoldings of the plasma membrane of ancestral prokaryotes
Plasma membrane
Cytoplasm
Endoplasmic reticulum
Nucleus
Nuclear envelope
Ancestral prokaryote
Cell with nucleus and endomembrane system
Figure 16.18A

3. Photosynthetic eukaryotic cell
Mitochondria and chloroplasts probably evolved from symbiotic prokaryotes that took up residence inside larger prokaryotic cells
Evidence comes from the fact that mitochondria, chloroplasts and centrioles all have their own DNA that is similar to the DNA of bacteria. It also replicates independently of the nuclear DNA.
Aerobic heterotrophic prokaryote
Mitochondrion
Mitochondrion
Photosynthetic prokaryote
Chloroplast
Some cells
Ancestral host cell
Photosynthetic eukaryotic cell
Figure 16.18B

4. Early protists were the ancestors of plants, animals, and fungi
Protists—unicellular eukaryotes and their close multicellular relatives—probably represent multiple kingdoms
Early protists were the ancestors of plants, animals, and fungi
The taxonomy of protists is in a state of flux
Figure 16.19

5. 16.20 Protozoa are protists that ingest their food
They include
flagellates
amoebas
Figure 16.20A, B

6. apicomplexans ciliates Red blood cell Apex Cilia Cilia Macronucleus
Figure 16.20C, D
Macronucleus

7. Most protozoa live freely in water or moist soil
Some live in humans and other animals and cause disease

8. Slime molds are protists that may constitute a distinct kingdom
Cellular slime molds have both unicellular and multicellular stages
Slime molds are protists that may constitute a distinct kingdom
Amoeboid cells
Sluglike colony
Reproductive structure
Figure 16.21