What is evidence of endosymbiosis?
- self replicating (binary fission)
- resemble bacteria in size and structure
- circular DNA
- 2 cell membrane
Describe the domain: Eukarya
- linear DNA
- membrane bound organelles (mitochondria and chloroplasts)
- larger than prokaryotes
- dynamic membrane -> ability to change shape
- diverse morphology -> well developed cytoskeleton
Why are eukarya and prokarya sister taxa?
- absence of peptidogylcan
- several kinds of RNA polymerase
- presence of introns
- unbranched hydrocarbon membrane lipids
- branched hydrocarbon membrane lipids
Explain the Oxygen Revolution
- began accumulating 2.7 billion years ago
- oxygen was toxic to most early taxa
- slowly adapted to oxygen rich atmosphere & began aerobic respiration
What are some possible selective advantages of sexual reproduction?
- meiosis is adaptive, may be able to thrive if the environment changes
- genotypes of many parasites & pathogens evolve quickly
How is diffusion related to the evolution of multicellularity?
hypothesis #1 - larger sizes are advantageous
- diffusion is effective only over short distances, you want a higher surface to volume ratio
What are the nutritional modes of protists?
- protozoans: animal-like protists
- fungus-like protists
- algae: plant-like protists
- mixotrophs
Name 4 Supergroups
- Excavata
- SAR Clade ( Stramenophiles, Alveolates, Rhizaria )
- Archaeplastida
- Unikonta
Describe the Archaeplastids Group
- contains red and green algae, as well as land plants
- chloroplasts have two membranes
Describe Red Algae
- pigment turns it red, masking green chlorophyll
- multicellular seaweeds
Describe Green Algae
- chlorophytes -> chlorophyll produces green pigment, contains unicellular & multicellular species
- charophytes -> complex, multicellular organisms, closely related to land plants
What are red and green algae closely related to?
plants !!
Describe the Chromalveolata Group
- may have originated by secondary endosymbiosis
- controversial clade (stramenophiles and alveolates)
- only united by DNA
Describe Apicomplexans
- mostly parasitic ( malaria )
- heterotrophic “protozoans”
Describe Ciliates
- very large diverse group
- heterotropic
- reproduce using binary fission and sometimes conjugation
ex) paramecium
Describe Diatoms
- unicellular algae
- membrane made of silica ( super strong )
Describe Dinoflagellates
- two flagella
- cell reinforced by cellulose plates
- aquatic phototrophs, heterotrophs & mixotrophs
- photopigment = red plastids
- some produce toxins
- some can glow
- “red tide”
Describe the Excavata Group
- highly variable
- mostly heterotrophic “protozoans”
ex) “sleeping sickness”, diaherra
Describe Unikota
- lack plastid genes
- no chloroplasts
Define asexual reproduction
- mitosis and cell division in eukaryotic organisms
- results in daughter cells that are genetically identical to the parents
Why should we study protists?
- impact on human health and welfare
- ecological importance
- critical to understanding evolution of plants, fungi, and animals
