Chapter 28: Protists Flashcards
what is a protist
term used to refer to all eukaryotes that are not plants, animals, or fungi
what do eukaryotic cells have
organelles
the organims in most eukaryotic lineages are what
protists
are most protists unicellular or multicellular
unicellular
why are protists not considered a kingdom
because some protists are more closely related
to plants, fungi, or animals than other protists
what do protists exhibit more than any other group of eukaryotes
structural and funcitnal diversity
why are single-celled protists complex
carry out all functions of life
what are some examples of cellular organization with membrane bound organlles
nucleus, golgi ap, ER, lysosomes
what can protists be categorized in
photoautotrophs,(chloroplast), heterotrophs( absorb organic molecules or ingest large food particles), mixotrophs ( combine photoynthesis and heterotrophic nutrition
how do protists reproduce
asexually, and some produce through meiosis
where does protist diversity have its origins
endosymbiosis
what is endosymbiosis
relationship between two species in which one organism lives inside the
cell or cells of the other organism (the host)
where is the mitochondria and plastid derived from
bacteria (prok) that were engulfed by ancestors of early eukaryotes
what did molecular analysis indicate about the evolution of mitochondira and plastid
evolved only once in the history of life
what evolved first mitochondria or plastid
mitochondira
how did mitochondria rise
alpha proteobacterium
gram negative bacteria
evolution of mitochondira gave rise to what
eukaryotes
how did plastids rise
a heterotrophic eukaryote engulfed a photosynthetic
cyanobacterium
how many membranes do cyanobacteria, and plastids of red and green algae have
2
what ingested the red and green algae themselves what is the process called
heterotrophic eukaryotes, secondary endosymbiosis
what is a nucleomorph
the engulfed cell contains a vestigal nucleus
what is the clade excavata characterized by
cytoskeleton
excavates include what
protists with modified mitochondria
what do exacavted memebrs have
feeding groove on one side of the body
what groups are excavates
three monophyletic
groups: the diplomonads, parabasalids, and
euglenozoans
what do both dipomonads and parabasalids have in common
- lack plastids
- reduced mitochondira
diplomonads
- equal sized nuclei + multple flagella
- many are parasites like giardia intestinalis
parabasalids
- reduced mitochondria called hydrogenosomes
- trichomonas vaginalis ( sexually transmitted parasite)
what is a euglenozoans
diverse clade
including predatory heterotrophs,
photosynthetic autotrophs, mixotrophs,
and parasites
main feature of euglenozoa
e distinguishing the
clade is a spiral or crystalline rod
inside each flagella
what does euglenozoans include
kinetoplastids, and euglenids
kinetoplastids
single mitochondrion
containing an organized mass of DNA called a
kinetoplast
-Free-living species are consumers of prokaryotes
in freshwater, marine, and moist terrestrial
ecosystems
- trypanosoma: causes sleeping sickness in humans
what are euglenids
one or two flagella that emerge from a pocket at one end of the cell
- some species are mixotrophs that switch between autotrophic and heterotrophic modes,
depending on the environmental conditions
what is a highly diverse group of protists
SAR
what is SAR
monophyletic supergroup named for the first letters of its three major clades:
Stramenopiles, Alveolates, and Rhizarian
what group is the most controversial between the different protists
SAR
stramenopiles
-include some of the most important photosynthetic organisms on Earth - hairy flagellum paired with smooth - diatoms, oomycetes, brown algae
diatoms
-unicellular algae with a unique two-part, glass-like wall of silicon dioxide - major component of phytoplankton and are highly diverse -
why do scientists advocate to fertilize the ocean with iron
promote diatom blooms and
facilitate movement of CO2
to the bottom of the
ocean
what alage is the largest and most comples
brown algae
brown algae
- multicellular algae
- species commonly known as seeweed
what produces the brown color of brown algae
Carotenoids in the plastids
plant like structures of brown algae
: the
rootlike holdfast, which anchors the alga, and a
stemlike stipe, which supports the leaflike blades
what helps keep brown algae structures near water’s surface
filled, bubble-shaped floats to keep
photosynthetic structures near the water surface
what does brown algae lack
true tissues and
organs
brown algae is important to who
humans
- laminaria are eating
what is the most complex life cycle
alteration of generations
what is alteration of generatoins
both haploid and diploid stages are multicellular
what is the diploid generation called
sporophyte; produces spores
haploid spores
develop into multicellular haploid
gametophytes that produce haploid gametes
fertalization of gametes results in what
diploid zygote, which develops into a new sporophyte
how is laminaria different than others
Heteromorphic species, such as Laminaria, have
structurally different gametophytes and sporophytes
what is isomorphic
gametophytes and
sporophytes that look similar to each other
what does oomycetes include
water molds, white rusts, and
downy mildews
why were oomycetes misidentified as fungi
due to their
multinucleate filaments that resemble fungal
hyphae
what are oomyctes cell walls composed of
cellulose rather than chitin (for fungi)
why are oomy. different from fungi
molecular analysis shows they are different
what are oomyctes more related to
plastid-bearing groups,
but do not have plastids or perform photosynthesis
alveolates
membrane-enclosed
sacs (alveoli) just under the plasma
membran
Three clades included in the alveolates
Dinoflagellates
– Apicomlexans,
– Ciliates
dinoglagellates
- abundant in marine and freshwater plankton
- 2 flagella in armor like cellulose plates
- ## diverse group
what are toxic red tides caused by
dinoflagellate blooms bc of the carotenoids in their plastids
apicomplexans
- most are parasitres of an animal
- serious human disease
how do apicomplexans spread
host as infectious cells
called sporozoites
what is merozoite
infects red blood cell
what is sporozoites
infect liver cells
life cycles of apicomplexans
sexual and asexual stages and require two or more different hosts
what apicoplexan causes malaria
plasmodium
how many people die from malarie each year
200 million people
what can plasmodium do
change its surface proteins; avoid
detection in the host immune
why are ciliates named
named for their use of cilia to move around and feed on bacteria or other protists
ciliates have 2 types of nuclei
micronuclei and large macronuclei, each cell has one or more copies of each type
macronuclei
multiple copies of the
genome
micronuclei
may be diploid or haploid,
depending on the life stage
what does genetic variation result from
conjugation
what is conjugation
two individuals
exchange haploid micronuclei
(without reproduction
what happens to the macronucleus during binary fission
dissolves
many species of rhizarians are what
amoebas
what are amoebas
protists that move and feed
using pseudopodia, extensions of the cell
surface
how are rhizarian amoebas different from other amoebas
hreadlike
pseudopodia. Non-amoeboid rhizarians
have flagella to move
3 clades of rhizarians
- radiolarians
- forams
- cercozoans
radiolarins
- delicate symmetrical skeleton
- pseudopodia and microtubules radiate
- cytoplasm covering microtubules engulf prey
that become attached to the pseudopodia
what are most radiolarians
marine organisms
what are forams named for
porous calcium carbonate shells, called tests
where do pseudopodia extend in the test
through the pores
how are forams nourished
photosynthetic activity of symbiotic algae
where do forams live
ocean and freshwater
how can researchers measure content in fossilized forams
use the magnisum content
what are cercozoans
amoeboid and flagellated protists
that feed using threadlike pseudopodia
where are cercozoans found
marine, fresh water, and soil ecosystems
what are most cercozoans
heterotrophic parasites or predators
what is the paulinella chromatophora
cercozoan autotroph
with a unique photosynthetic structure called a
chromatophore
what are chlorarachinophytes
small group of mixotrophs
what are the closest relative to plants
red and green algae
what did ancient protist evolve into
red algae and green algae
plants are descended from what
green algae
what is the supergroup that includes red algae, green algae, and plants
archaeplastida
what is phycoerythrin and how does it affect algae
masks the green of chlorophyll giving red algae its color
how does color of red algae vary
varies from greenish-red in shallow
- dark red or black in deep water
what is the largest red algae
seeweed, multicellular
reproduction in red algae
sexual and include alternation of generations
where is red algae common
costal waters or tropical oceans
which species of red algae are consumed by humans
-porphyra (nori) used to wrap sushi
what are green algae named for
green chloroplasts, which
are structurally and chemically similar to those found in
plants
what group does green algae form
paraphyletic group that includes:
charophytes and chlorophytes
charophytes
algae most closely related to plants
where do chlorophytes live
in fresh water
how did algae become larger and have greater complexity
- formation of colonies
- formation of true multicelluar bodies
- repeated division of nuclei
unikons
include protists that are closely related to fungi and animals
2 major clades of unikons
Amoebozoans: tubulinids and relatives
– Opisthokonts: animals, fungi, and related
protists
amoebozoans
amoebas that
have lobe- or tube-shaped
-tubulinids,slime
molds, and entamoebas
slime molds/ mycetoxoans
once thought
to be fungi due to their spore-producing fruiting
bodies
slime mold lineages
plasmodial slime
molds and cellular slime molds
tubulinids
diverse group of amoebozoans with lobe- or tube-shaped pseudopodia - unicellular protists -found in soil and freshwater and marine - most are heterotrophic and consume bacteria
plasmodial slime molds
- brightly colored often yellow or orange
- form a large feeding mass called plasmodium
- plasmodium undivided by plasma membranes contains many diploid nuclei
cellular slime molds
multicellular
aggregates in which cells are separated by
plasma membranes
what does the feeding stage of cellular slime molds consist of
solitary cells
- food is low = cells form aggregate
- aggregate will form fruiting body
- cells in stalk of fruiting body die
what is Dictyostelium discoideum
a model organism
for the studying the evolution of multicellularity
entamoeba
parasites of all classes of vertebrates and some invertebrates
humans host at least 6 species but which one is pathogenic
E. histolytica is pathogenic
what does
E. histolytica cause
amoebic dysentery, the third-leading cause of death due to eukaryotic
parasites
opisthokonts
diverse group including animals, fungi, and several groups of protist
where are protists found
diverse aquatic and moist terrestrial environments
key roles of protists in their habitats
symbiont and that of producer
symbiotic protitst
- protists can benefit their host
- protists can be parasites
photosynthetic protists
- producers that obtain energy from the sun to convert it to CO2
who are the main producers in aquatic communities
photosynthetic protists and
prokaryotes
what happened to protists as the temp increased
Growth and biomass of photosynthetic protists has
declined as sea surface temperature has increased
what do phytoplankton communites rely on
upwelling of cold nutrient rich water from below
