protist diversity
- chromalveolates
a) diatoms
b) dinoflagellates
c) brown algae
d) water molds
e) ciliates - rhizarians
a) forminiferans
b) radiolarians
3.Excavata
- Uniknots
a) plasmodial slime molds
b) cellular slime molds - Archeaplastuids
a) red algae
b) green algae
chromalveolata: diatoms
-unicellular
-unique
-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
- autotrophic
- 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
- fungus-like
- 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
- unicellular
- heterotrophs and mixotrophs
- use cilia to swim/crawl
- ex) paramecium
- chromoalveolata also include plasmodium
- causeitive agent of malaria
- transmitted by mosquitos
Rhizarians
- 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
excavata
- 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
uniknots
-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
-plasmodium
=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
archaeplastids
- 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
- ancesteral colony of flagellated protists may have formed
- a cell divided and offspring remained attached to one another - cells of the colony may have become slightly specialized and interdependent
- different cells types became more and more efficient at preforming specific tasks - additional specialization may have led to differentiation in between sex cells and non-reproductive cells
