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33 Cards in this Set
- Front
- Back
prokaryotes
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earliest organisms, cells lacked true nuclei
2 distinct groups--bacteria and archaea have been around 3.5 billion years reproduce by binary fission |
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where prokaryotes are found
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in every conceivable habitat
a. halophiles (salt lovers) b. thermophiles (heat lovers) c. methanogens (oxygen free) |
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structure of prokaryotes
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1. lack a membrane-bound nucleus
2. ribosomes only 3. cell wall outside plasma membrane 4. some have one or more flagella 5. small, unicellular organisms |
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domain bacteria
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most prokaryotes
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domain archaea
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more closely related to eukaryotes than to bacteria
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types of prokaryotes
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1. cocci--spherical
2. bacilli--rod shaped 3. spirochetes--spiral shaped |
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how prokaryotes obtain nutrition
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1. photoautotrophs--use sunlight and CO2
2. chemoautotrophs--use inorganic compounds for energy (H2S, NH3, CO2) 3. photoheterotrophs--use sunlight and organic compounds 4. chemoheterotrophs--need organic molecules from the environment |
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endospores
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a thick-coated, protective cell produced within a bacterial cell exposed to harsh conditions
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pathogens
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bacteria and other organisms that cause disease (form of prokaryote)
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exotoxins
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poisonous proteins secreted by bacterial cells
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endotoxins
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chemical components of the cell walls of certain bacteria
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roles of prokaryotes
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1. decomposers
2. required for nitrogen fixation |
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bioremediation
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use of organisms to remove pollutants from water, air, or soil
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protists
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any eukaryote that is not a plant, animal, or fungus
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eukaryotes
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evolved from prokaryotes 1.7 billion years ago
2 step process for evolution a. all membrane-bound organelles EXCEPT mitochondria and choloroplasts derived from inward folding of plasma membrane b. mitochondria and chloroplasts derived from endysymbiosis |
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endosymbiosis
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refers to one speicies living inside another host species
(symbiosis--"living together" close association between organisms of two or more species) |
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mitochondria
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evolved from slal, aerobic heterotroph prokaryote living inside a host
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choloroplast
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evolved from small, photoautotroph prokaryote living inside a host
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3 major groups of protists
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1. protozoans
2. unicellular algae 3. seaweeds |
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protozoans
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--protists that live primarily by ingesting food, a mode of nutrition that is heterotrophic and animal-like
-live in wet or moist habitats -some are disease causing parasites |
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5 groups of protozoans
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1. flagellates
2. amoebas 3. forams 4. apicomplexans 5. ciliates |
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flagellates
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protozoans that move by means of one or more flagella
most are free living and some are parasites |
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amoebas
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no flagella or cilia for movement
move and feed by way of pseudopodia |
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pseudopodia
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temporary extensions of the cell
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apicomplexans
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-all are parasitic
-some cause serious human diseases -named for an apparatus at their apex (tip) that is specialized for penetrating host cells and tissues |
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ciliates
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protozoans that use locomotor structures called cilia to move and feed
-nearly all are free-living (nonparasitic) |
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algae
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photosynthetic protists
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plankton
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the communities of organisms, mostly microscopic, that drift or swim weakly near the surfaces of ponds, lakes, and oceans
aka phytoplankton |
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3 groups of unicellular algae
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single-celled, photosynthetic algae
--another major group of protists 3 types 1. dinoflagellates 2. diatoms 3. green algae |
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dinoflagellates
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abundant in aquatic pastures of phytoplankton
-move with flagella -population explosions produce "red-tides" (responsible for major fish kills esp. in tropics) |
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diatoms
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have glassy cell walls containing silica, the mineral used to make glass
--massive accumulations of fossilized diatoms make up thick sediments known as diatomaceous earth, is mined for its use as a filtering material, an abrasive, and a natural insecticide |
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green algae
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named for their chloroplasts
-in most freshwater lakes and ponds, and pools and aquariums -unicellular but some colonial (volvox) |
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seaweeds
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large, multicellular marine algae
-grow on rocky shores -implies plantlike, but similarities between these algae and true plants are a consequence of convergent evolution |