Eukaryotic Protists Flashcards
Protists differ from bacteria because …
- they are 30-40x the size of bacteria
- contain membrane organelles
- have linear chromosomes opposed to circular DNA
- DNA is packed with histones like multicellular organisms
Nutrition
Usually aerobic or facultatively anaerobic
Autotroph
Organism that obtains organic food molecules w/o eating other organism or substances derived from other organisms. Uses light from sun or oxidation of inorganic molecules to make organic molecules.
Heterotroph
Organism that obtains organic food molecules by eating other organisms or substances derived from other organisms.
Mixotroph
Organism capable of both photosynthesis and heterotrophy
Examples of photosynthetic protists
Euglena (no cell wall, has plasma membrane and flagella) and Diatoms (glass cell wall)
Indicates that photosynthesis was individually acquired
How are protist flagella different from flagella of bacteria
9x2 complex system of cables with plasma membrane instead of simple thread-like structure of bacteria
means of motility of protists
flagella and cilia
Two possible life cycles seen in protists
Binary fission (asexual, common) Alternation of Generation (sexual)
Habitats
aquatic: salt water, freshwater, soil
How is soil an aquatic enviornment
Soil has water film surrounding each soil particle. Protists are able to move through water films.
Example of parasitic protists
Giardia
Plasmodia (malaria)
Naturalistic explanations are …
speculations
Evidence for theory of endosymbiosis
- mitochondrial asexual fission like bacteria
- mitochondrial DNA like alpha bacteria and chloroplast DNA like cyanobacteria
- Chloroplast small-subunit RNA are virtually identical to cyanobacteria
- Chloroplast size resembles cyanobacteria, mitochondria size resembles bacteria
Parasitology
- dependent parasites that kill hosts will die quickly
- ideal parasite is neutral or beneficial to host
