Brief History of Life Facts
-earth formed approximately 4.5 billion years ago
-first life originated around 2.5 billion years ago
-Cyanobacteria evolved to gather sunlight to do photosynthesis and produce oxygen
Symbiosis and the Origin of Eukaryotes
-Lynn Margulis and the Endosymbiotic Theory
-Mitochondria and chloroplasts are both believed to have developed from prokaryotes by a process called endosymbiosis
Endosymbiotic Theory
[inside symbiosis]
any two things coming together and having a relationship
the earlier forms of life were prokaryotic cells that evolved through endosymbiosis into Eukaryotic Cells
Protists
-extremely variable
-most diverse kingdom in Eukarya
-they are not plants, fungi, or animals
they have:
-varied types of cell surfaces
-movement is accomplished by diverse mechanisms
-many forms of nutritional acquisition
There are about ...
200,000 different forms of protists including,
-unicellular
-colonial
-multicellular
Unicellular
comprised of 1 cell
Colonial
permanent collection of cells that show little or no integration of cellular activities
Multicellular
the activities of individual cells are coordinated
key advantage: it allows for specialization of cells [separation of labor]
Protists can be:
-phagotrophs (animal-like) heterotrophs
-slime molds (fungi-like)
-Unicellular or Multicellular algae (plant-like) photoautotrophs
Choanoflagellates
closest living relatives to animals
Green algae
closest living relatives to plants
Varied Cell Surfaces
all have a cell membrane, but many have cell walls or glass (silica) shells
Cellulose
what cell walls are made of
Varied Nutritional Aquisitions
1. Phototrophs [are photosynthetic autotrophs]
2. Phagotrophs [heterotrophic] - one organism ingesting a rather large organism
3. heterotrophs and decomposers
any protist that is greenish has chlorophyll and can make their own food
Varied Movement Mechanisms
1. Cilia
2. Flagella
3. Pseudopods "fake feet"
4. Gliding
Cysts
some protists can survive harsh environmental conditions by forming these
are dormant forms of cells with resistance outer covering in which cell metabolism is more or less completely shut down
Brain-Eating Amoeba
organisms that form cysts
impervious to the hosts immune system
WBC can't get through the cysts (coat)
How protists reproduce
mostly asexually
only reproduce sexually in times of stress
Common ways of protist reproduction
-binary fission [two equal organisms]
-budding [small amount comes off then grows into full size]
Amoeba
-unicellular
-heterotrophic (phagocytosis)
-Pseudopods
-contractile vacuole
-Fungi-like
Chlamydomonas
-unicellular
-autotrophic (green)
-Flagella
-contractile vacuole
-eyespots
-Plant-like
Volvox
-colonial
-Autotrophic (green)
-Flagella (rotating)
-no specialization
-Plant-like
Paramecium
-unicellular
-heterotropic
-Cilia
-oral groove
-contractile vacuole
-Animal-like
Ulva (sea lettuce)
-multicellular
-autotrophic
-non-motile
-no specialization
-Plant-like