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Flashcards in lecture 8 Deck (18):

protist diversity

1. chromalveolates
a) diatoms
b) dinoflagellates
c) brown algae
d) water molds
e) ciliates

2. rhizarians
a) forminiferans
b) radiolarians


4. Uniknots
a) plasmodial slime molds
b) cellular slime molds

5. Archeaplastuids
a) red algae
b) green algae


chromalveolata: diatoms

-autotrophic protist
-cell wall consists of two halves that fit together like the top and bottom of a shoe box
-found in marine and fresh water environments
-the organic molecules diatoms produce are an important food source in all aquatic enviornments
-food is stored in the form of oil and sugar droplets
-the advantage of oil droplets is two fold:
rich source of energy
oil makes the diatoms buoyuant and keeps them floating near the surface of water where sunlight is plentiful
-fossilized diatoms form sediment -diatomaceous earth


chromalveolata: dinoflagellas

-commonly found on marine or fresh water plankton
-some are:
autotrophic, heterotrophic, mixothrophic
-dinoflagella blooms can cause warm coastal waters to turn a pinkish- orange
-called red tide
-produce toxins which have killed large quantities of fish


chromalveolata: brown algae

-large and complex
-brown color due to pigments in their chloroplasts
-all multicellular
-most marine
-brown algae is what we commonly call seaweed
-ex) kelp is an underwater bed of brown algae


chromalveolata: water moulds

-heterotrophic and unicellular
-decompose dead plants and animals n fresh water habitats
-sometimes parasitic water molds grow on the skin and gills of fish


chromalveolata: ciliates

-large and diverse group
-use cilia for movement and feeding
-heterotrophs and mixotrophs
-use cilia to swim/crawl
-ex) paramecium
-chromoalveolata also include plasmodium
-causeitive agent of malaria
-transmitted by mosquitos



-referred to as amoebas
-protists that move and feed using pseudopodia
-these pseudopodia are different than those other amoebas because these are threadline
-alternative amobas have lobe like pseudopodia


Rhizarians: forminiferans

-found in ocean and fresh water
-have tests:
-tests are porous shells composed of oragnic material hardened by calcium carbonate
-pseudopodia extend through small holes in the test
-pseudopodia are used for feeding and movements
-fossilized tests form sedimentary rock


Rhizarians: radiolarians

-produce an internal skeleton made of silica
-the cell is also surrounded by a test made of organic material
-many species are marine
-when they die they settle to the bottom of the ocean and become sediments



-these are autotrophic, heterotrophic, and mixotrophic protists
-likely represent the most ancient surviving lineage of eukaryotes
-modified mitochondria: no electron transport system
-most are anaerobic
-use glycolosis and other anaerobic pathways to produce ATP
-ex) giadia intestinails: a waterborne parasite causing servere diarrhea
-parasites derive nutrition from their host, the host is harmed during the process
-trichomanas vaginalis a sexually transmitted parasite belongs to this group
-typanosma spp. are parasites that can be passed to humans via insect bites ex) african sleeping sickness spread by the african tsetse fly
-euglena spp. are common inhabitants of pond water



-use pseudopodia to move and feed
-pseddopodia are temporary lobe-like extensions
of the cell
- this group includes:
-free living amoebas
-some parasite amoebas
-slime molds
1. plasmodial slime mold
2. cellular slime molds


uniknots: plamodial slime molds

-commonly found where there is moist, decaying organic matter
-often brightly pigmented
=not multi cellular
=single, multi nucleate mass of cytoplasm
-----undivided by plasma membranes
-----different than plasmodium that causes malaria
-extends pseudopodia through soil and rotting logs
=engulfs food by phagocytosis as it grows
-cytoplasm moves through fine channels in one direction and then the opposite
=these pulsing flows help to distribute nutrients and oxygen
-when food and water are limited the plasmodium stops growing and differentiates into reproductive structures that produce spores
=when conditions become favorable the spores release haploid cells that fuse to form a zygote allowing life cycle to continue


Uniknots: ceullar slime molds

-common on rotting logs and decaying organic matter
-usually they exist as solo amoeboid cells
-when nutrients are scarce they swarm together forming a slug like clump of cells that travels around for a short time
-some of these cells will then dry up and form a stalk
-the stalk supports an asexual reproductive structure
-in this structure cells develop into spores



-mainly autorophic
-red algae, green algae and land plants


archaeplastids: red algae

-live in warm coastal waters of the tropics
-red because of an extra pigment that masks the green of cholophyll
-most multicellular
-usually soft bodied although some have cells walls with hard chalky deposits
-hard bodied red algae are commonly found on coral reefs


archaeplatids: green algae

-named because of their green grass color
-unicellular, colonial and multicelluar members
-generally have complex life cycles


life cycle of green algae

ex) multicellular Ulva
-complex life cycle of multicellular green algae is characterized by an alternation of generations
-multicellular diploid form 2n alternates with multicellular haplopid n form
-this alternation of generations occurs in many multicellular algae as well as in all plants
-gametophytes: multicellular haploid form
-sporophytes: multicellular diploid form


evolution of multiceullarity

1. ancesteral colony of flagellated protists may have formed
-a cell divided and offspring remained attached to one another
2. cells of the colony may have become slightly specialized and interdependent
-different cells types became more and more efficient at preforming specific tasks
3. additional specialization may have led to differentiation in between sex cells and non-reproductive cells