evo of eukaryotes; protists Flashcards
8 major steps in evolution timeline
- origin of solar system
- prokaryotes
- atmospheric oxygen
- single cell eukaryotes
- multi-cell eukaryotes
- animals
- colonization of land
- humans
What is the endosymbiotic theory?
hypothesis for the origin of eukaryotic cells
3 steps in endosymbiotic theory
- the plasma membrane in an ancestral prokaryote in-folded on itself to create nuclear membrane and ER
- ancestral prokaryote engulfs another aerobic heterotrophic prokaryote (which becomes mitochondria) to produce ancestral heterotrophic eukayote
- ancestral prokaryote also engulfs photosynthetic prokaryote (becomes chloroplast) which produces ancestral photosynthetic eukaryote
What are the major pieces of evidence for symbiotic theory? 6
Prokaryotes, mitochondria, and chloroplasts have a lot of similarities.
- both replicate themselves same same
- ribosomes found in mito and chloroplasts are more similar to prokaryotic than eukaryotic ribosomes
- they all have circular DNA
- similar enzymes and transport systems
- small in size
- mito and chloroplast contain structure needed to transcribe and translate their DNA into protein
What is a protist?
An organism that is eukaryotic, but not a plant, animal, or fungi
what are protists main role in biosphere?
Are producers and symbionts.
-up to 1/4 of the worlds photosynthesis come from aquatic protists -> this is important and gets taken up the food chain
Give example of protist in mutualism, and in parasitism
Parasitism:
Phytophthora infestance causes Late potato blight, protist gets food, potatoes rot in the ground
Mutualism:
Wood digesting protist lives in the gut of termites and helps them to break down cellulose. protist -> food, termite -> also food
most atmospheric oxygen is of what origin?
biological
-likely from photosynthetic bacteria
