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33 Cards in this Set

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  • Back
prokaryotes
earliest organisms, cells lacked true nuclei

2 distinct groups--bacteria and archaea

have been around 3.5 billion years

reproduce by binary fission
where prokaryotes are found
in every conceivable habitat

a. halophiles (salt lovers)
b. thermophiles (heat lovers)
c. methanogens (oxygen free)
structure of prokaryotes
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
domain bacteria
most prokaryotes
domain archaea
more closely related to eukaryotes than to bacteria
types of prokaryotes
1. cocci--spherical
2. bacilli--rod shaped
3. spirochetes--spiral shaped
how prokaryotes obtain nutrition
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
endospores
a thick-coated, protective cell produced within a bacterial cell exposed to harsh conditions
pathogens
bacteria and other organisms that cause disease (form of prokaryote)
exotoxins
poisonous proteins secreted by bacterial cells
endotoxins
chemical components of the cell walls of certain bacteria
roles of prokaryotes
1. decomposers
2. required for nitrogen fixation
bioremediation
use of organisms to remove pollutants from water, air, or soil
protists
any eukaryote that is not a plant, animal, or fungus
eukaryotes
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
endosymbiosis
refers to one speicies living inside another host species

(symbiosis--"living together" close association between organisms of two or more species)
mitochondria
evolved from slal, aerobic heterotroph prokaryote living inside a host
choloroplast
evolved from small, photoautotroph prokaryote living inside a host
3 major groups of protists
1. protozoans
2. unicellular algae
3. seaweeds
protozoans
--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
5 groups of protozoans
1. flagellates
2. amoebas
3. forams
4. apicomplexans
5. ciliates
flagellates
protozoans that move by means of one or more flagella

most are free living and some are parasites
amoebas
no flagella or cilia for movement

move and feed by way of pseudopodia
pseudopodia
temporary extensions of the cell
apicomplexans
-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
ciliates
protozoans that use locomotor structures called cilia to move and feed

-nearly all are free-living (nonparasitic)
algae
photosynthetic protists
plankton
the communities of organisms, mostly microscopic, that drift or swim weakly near the surfaces of ponds, lakes, and oceans

aka phytoplankton
3 groups of unicellular algae
single-celled, photosynthetic algae

--another major group of protists

3 types
1. dinoflagellates
2. diatoms
3. green algae
dinoflagellates
abundant in aquatic pastures of phytoplankton

-move with flagella
-population explosions produce "red-tides" (responsible for major fish kills esp. in tropics)
diatoms
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
green algae
named for their chloroplasts

-in most freshwater lakes and ponds, and pools and aquariums

-unicellular but some colonial (volvox)
seaweeds
large, multicellular marine algae

-grow on rocky shores
-implies plantlike, but similarities between these algae and true plants are a consequence of convergent evolution