BIOL10004 Chapter Notes - Chapter Readings 3 and 4: Polyphyly, Protist, Nuclear Membrane
11 Jun 2018
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Eukaryotes
Pg. 889-892
The Protists
- single-celled organisms (unicellular)
- live in aquatic habitats
- photosynthetic protists are major primary producers in lakes, rivers and
oceans -> release at least 30% of the planet’s oxygen into atmosphere
- herbivorous protists link algal primary producers and larger animal
consumers
- parasitic protists are responsible for human diseases (eg. Malarisa,
sleeping sickness and dysentery)
- also parasite other animals and plants -> agricultural losses
- polyphyletic – belong to multiple phyla
Protists are a diverse group of eukaryotes
- based together based on nutrition
o autotrophic – produce food by photosynthesis
▪ eg. Algae,
o heterotrophic – consumers of organic substances or other
organisms
▪ protozoa (ate smaller organisms)
▪ fungi – protists that absorbed small food molecules from
environment
- NOW:
o Alveolates – have photosynthetic, parasitic and predatory
members, but all are close relatives based on comparison of the
fine structural details of their cells and DNA sequences
- Grouped into kingdom: Protista
Protists may be photosynthetic, parasitic and predatory or absorb small food
molecules from the environment.
Relationships among them are still unclear but they are a diverse range of
eukaryotic cell types, and the kingdom Protista is polyphyletic
Where did eukaryotic cells come from?
Origin of the nucleus
- eukaryotes have nuclear envelope and multiple linear chromosomes
o prokaryotes lack and have single circular chromosome
- origin of linear chromosome:
o transformation from circular to linear might have arisen from a
break in the circle and duplication of the linear chromosome to
give multiple copies
- origin of nuclear envelope
o accumulation of vesicles resulting from infolding of cell membrane
around prokaryotic nucleoid
▪ known to occur in cyanobacteria
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Herbivorous protists link algal primary producers and larger animal single-celled organisms (unicellular) live in aquatic habitats. Photosynthetic protists are major primary producers in lakes, rivers and oceans -> release at least 30% of the planet"s oxygen into atmosphere. Parasitic protists are responsible for human diseases (eg. malarisa, Also parasite other animals and plants -> agricultural losses sleeping sickness and dysentery) Protists may be photosynthetic, parasitic and predatory or absorb small food molecules from the environment. Relationships among them are still unclear but they are a diverse range of eukaryotic cell types, and the kingdom protista is polyphyletic. Eukaryotes have nuclear envelope and multiple linear chromosomes: prokaryotes lack and have single circular chromosome. Origin of linear chromosome: transformation from circular to linear might have arisen from a break in the circle and duplication of the linear chromosome to give multiple copies.
