protists Flashcards
list the unifying characteristics of eukaryotes**
nuclei, mitochondria, cytoskeletal elements, some lack flagella and or cilia, chromosomes organized by histones, mitosis, cell wall in some, and sexual reproduction in most
define protists**
all eukaryotes that are not plants, animals, or fungi
Explain the endosymbiotic theory**
eukaryotes may have been a product of one cell engulfing another, and coevolving over time until the separate cells were no longer recognizable as such
evidence: mitochondria: own genome, ribosomes and transfer RNA and two membrane
evidence: Plastids: have similarities to cyanobacteria
evidence:
describe the cell structure characteristics of protists**
can evolve int he absence of true multicellularity, some unicellular protists have organelles not found in most other eukaryotic cells
describe the metabolic diversity of protists**
most nutritionally diverse of all eukaryotes
exhibit many forms of nutrition and may be aerobic or anaerobic
photoautotrophs
heterotrophs
mixotrophs
phagocytosis
describe the reproduction and life cycle diversity of protists**
asexually or sexually
all three basic types of sexual life cycles animal, plant and fugal are represented among protists
identify the evolutionary relationships of plants, animals, and fungi within the six presently recognized supergroups of eukaryotes**
describe representative protist organisms from each of the supergroups**
identify defining features of protists in each of the supergroups**
describe the role that protists play in the ecosystem**
are found in diverse aquatic and moist terrestrial environments
symbiont and producer
where do protists live
soil, freshwater, brackish, and marine environments, digestive tracts of animal and the vascular tissues of plants
photoautotrophs
containing chloroplasts
heterotrophs
absorb organic molecules or ingest larger food particles
mixotrophs
combine photosynthesis and heterotrophic nutrition
phagocytosis
amoebas and some other heterotrophic protist species ingest particles
what are the supergroups of eukaryotes
excavata
sar
archaeplastida
unikonta
excavata
includes three clades parabasalids, diplomonads, and euglenozoans
modified mitochondria
spiral or crystalline rod inside flagella
SAR
includes stramenopila, alvelata, and rhizaria
- diatoms are important photosynthetic stramenopiles
- many rhizarians are amoebas with threadlike pseudopodia such as globigerina
hairy and smooth flagell a
membrane-enclosed sacs(alveoli) beneath plasma membrane
archaeplastida
includes red and green algae, and plants
include unicellular, colonial, and multicellular species like volvox
phycoerythrin
plant-type cloroplasts
unikonta
includes amoebas with lobe-or tube-shaped pseudopodia, animals, fungi, and non-amoeba protists closely related to animals or fungi
symbiotic protists
some protist symbionts benefit their host like dinoflagellates that live within the polyps and nourish reef-building coral
some protist invade the guts of termites and aid with the digestion of wood
some are parasites
photosynthetic protists
many protist are producers, organism that use energy from light to conver co2 to organic compounds
in aquatic communities, the main producers are photosynthetic protists and prokaryotes
all other organisms are consumers that directly or indirectly depend on producers for food
photosynthetic protists are limited by what
nutrients, populations explode when nutrients are added
population booms can have major ecological consequences, such as the formation of marine dead zones
growth and biomass of photosynthetic protist and prokaryotes ahve declined with increasing sea surface temperature
excavata- diplomonads
reduced mitochondria called mitosomes that lack electron transport chains
energy is derived from anaerobic pathwasy
two equal sized nuclei and multiple flagella
many are parasites
excavata-parabasalids
parabasalids have reduced mitochondria called hydrogenosomes that generate some energy anaerobically
hydrogen gas is released as a by-product of anaerobic metabolism
excavata-euglenozoans
a diverse clade including predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites
spiral or crystalline rod inside each flagella
includes the kinetoplastids and euglenids
single mitochondria
some are parasites
one or two flagella
SAR-Stramenopiles
hairy flagellum paired with a smooth flagellum
diatoms, oomycetes, and brown algae are three important groups of stramenopiles
SAR-stramenopiles-Diatoms
diatoms are unicellular algae with a unique two-part, glass-like wall of silicon dioxide
compose much of the phytoplankton in oceans and lakes
abundant and widespread
the breakdown and release of carbon stored in the diatoms on the ocean floor can take centuries.
SAR-Stramenopiles-brown algae
are the largest and most complex multicellular algae
carotenoids in the plastids produce the brown color
seaweed-lack the true tissues and organs found in plants
SAR-Stramenopiles-Oomycetes
include water molds, white rusts, and downy mildews
misidentified as fungi due to their multinucleate filaments that resemble fungal hyphae
oomycete cell walls are composed of cellulose, rather than chitin
no not have plastids or perform photosynthesis
acquire nutrients through parasitism or decomposition
SAR-Alveolates
have membrane-enclosed sacs(alveoli) just under the plasma membrane
three clades included in the alveolates are the dinoflagellates, apicomplexans, and the ciliates
SAR-Alveolates-Dinoflagellates
abundant components of marine and freshwater phytoplankton
have two flagella housed in the grooves of armor-like cellulose plates that surround the cell
beating of the spiral flagella cause dinoflagellastes to spin as the move through the water
bloom red tides
SAR-Alveolates-Apicomplexans
nearly all are apicomplexans
spread through the host as infectious cells called sporozoites
the apex(cell end) contians a complex of organelles specialized for penetrating host cells and tissues
sexual and asexual stages and require two or more different hosts
plasmodium (SAR?)
evades the host immune system by living inside cells and continually changing its surface proteins
SAR-alveolates-Ciliates
Ciliates are named for their use of cilia to move around and feed on bacteria or other protists
the cilia may completely cover the cell surface or be clustered in a few rows or tufts
SAR-Rhizarians
many are amoebas
amoebas are protists that move and feed using pseudopodia, extensions of the cell surface
threadlike pseudopodia
include radiolarians, forarms, and cercozoans
SAR- rhizarians-radiolarians
have delicate, symmetrical internal skeletons typically made from silica
pseudopodia reinforced by microtubules radiate from the central body
prey is engulfed by the cytoplasm in the pseudopodia and carried into the cell by cytoplasmic streaming
most are marine organisms
SAR-Rhizarians-Cercozoans
amoeboid and flagellated protists that feed using threadlike pseudopodia
heterotrophic parasites or predators
archaeplastida-red algae
phycoerythrin masks the greed of chlorophyll giving the color
most are multicellular
reproduction is sexual in red algae and life cycles often include alternation of generation
archaeplastida- green algae
names for their green chloroplast
form a paraphyletic group that includes the charophytes and the chlorophytes
evolved
1. formation of colonies from individual cells
2. formation of true multicellular bodies by cell division
3. repeated division of nuclei with no cytoplasmic division
Unikonta-amoebozoans
amoebas that have lobe-or tube-shaped rather than thread like pseudopodia
include tubulins, slime molds, and entamoebas
unikonta-amoebozoans-tubulinids
active predators of bacteria and other protists
common unicellular protists in soil
unikont- amoebozoans- slime molds
thought to be fungi due to their spore-producing fruiting bodies
have diverged into two lineages, plasmodial slime molds and cellular slime molds
brightly colored
unikonta- amoebozoans
