Chapter 28 Flashcards
What are protists, and what are they closely related to?
unicellular groups of eukaryotes
Closely related to plants, fungi, or animals than other protists
What domain are protists, and how do they get nutrition?
Eukarya
Can be photoautotrophs or heterotrophs
Can be mixotrophs- combine photosynthesis and heterotrophic nutrition
How can protists reproduce? (3)
Can be asexual, sexual, or at least undergo meiosis and fertilization
How do eukaryotic cells differ? (2)
Have nucleus and membrane-bound organelles
Well-developed cytoskeleton- for structure and shape
What do prokaryotes have instead of organelles?
subcellular organelles to carry out functions
What four supergroups of eukaryotes exist?
Excavata, “SAR” clade, Archaeplastida, and Unikonta
What does excavata mean, what does it have, what kind of organisms are in it, and what kind of taxonomic group is it?
“excavated feeding groove from one side of a cell body
Based on the study of their cytoskeletons
Modified mitochondria, flagella
Includes parasites, diplomonads, parabasalids, and euglenozoans
monophyletic
What is the SAR clade include?
includes important photosynthetic organisms like diatoms
Includes amoebas and malaria
What does the archaeplastida group include?
Algae and land plants
What does the group Unikonta includ?
ameobas, animals, fungi, and other protists
Why is the supergroup branching not reliable? (2)
Some branches are still under active debate
Shows that they diverge from a common ancestor simultaneously
This is not correct, but we know what organisms diverged first
Why are protists so diverse?
Because of endosymbiosis- when one organism lives inside the cells of a host
When did mitochondria evolve, and how?
evolved before plastids
Host cell engulfed an alpha proteobacterium that would later become a mitochondrion
The engulfing cell was from an archaeal lineage
how did plastids evolve?
A photosynthetic cyanobacteria gave rise to two lineages
What lineages did the original plastid evolve into?
Photosynthetic protists and algae
Algae underwent secondary endosymbiosis- they were ingested in the food vacuoles of heterotrophic eukaryotes and became endosymbionts themselves
How many membranes do cynanobacteria and plastids of red and green algae have?
2
How are transport proteins on red/green algae membranes related to those on cyanobacteria?
homologous
what are nucleomorphs?
genes found in nucleus that act as a vestigial nucleus in plastids, similar to found in green algae
What are diplomonads (3)
possess mitosomes (reduced mitochondria)
Lack a functioning ETC and cannot use oxygen for glycolysis
Possesses two equal-sized nuclei and multiple flagella
ex- giardia intestinalis
What are parabasalids? (2)
possess hydrogenosomes (reduced mitochondria)
Can generate some energy anaerobically, releasing hydrogen gas as a byproduct
ex- trichomonas vaginalis
How do diplomonads and parabasalids relate?
lack plastids and have highly modified mitochondria
Found in anaerobic environments
What are euglenozoans?
Diverse clade of predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites
Possess a rod with either spiral or a crystalline structure inside their flagella
What are kinetoplastids?
possess kinetoplast (single, large mitochondrion containing mass of DNA)
ex- trypanosoma (sleeping sickness)
How do kinetoplastids evade immune responses?
by switching surface proteins
Due to mutations by producing millions of copies of genes
What are euglenids?
possess a pocket at one end of the cell from which one or two flagella emerge
Some are mixotrophs
How do euglenids obtain energy?
They are mixotrophs, depending on light availability
What are the three major clades in the SAR clades, and how are they similar (3)
stramenopiles, alveolates, and rhizarians
Monophyletic
Similar genome DNA sequence
When did stramenopiles and alveolates originate, and how? (4)
originated more than a billion years ago
Common ancestor engulfed a single, photosynthetic red alga
Emerged from secondary endosymbiosis
Some lack plastids or their remnants
The reason for this is still unknown
What do stramenopiles have, and examples? (3)
possess flagellum wiith numerous fine, hairlike projection
Paired with a nonhairy flagellum
Includes important photosynthetic organisms like diatoms, golden algae, and brown algae
What are diatoms? (2)
unicellular algae that have a glass-like wall made of silicon dioxide embedded in an organic matrix
So abundant that they affect global carbon levels
Can bloom when ample nutrients are available
What is the structure of a diatom wall, and where are they found?
Wall consists of two overlapping parts
Wall provides protection from pressure
Massive accumulations of fossilized diatoms wall are major constituents of diatomaceous earth
What do golden algae possess, and how do they obtain energy? (3)
possess biflagellated cells (two flagella attached near one end of the cell)
Components of plankton
Some are photosynthetic, some are mixotrophs
What are brown algae? (2)
largest and most complex algae
Multicellular
What makes up the brown algae, and how did they evolve? (4)
Some possess holdfast- specialized tissues and organs that anchor the alga
Some have a stipe- stem
Supports blades- leaves
Holdfast, stipe, and blades evolved independently from plants
Algae adapted to enable photosynthetic surfaces to be near the surface
What is alternation of generation?
Life cycle of algae
Alternation of multicellular haploid and diploid cells
What are diploid cells in alternation of generation called, and what doe it produce?
sporophytes, producing haploid zoospores
How do zoospores move, and what do they develop into?
Zoospores develop into haploid, multicellular gametophytes, which produce gametes
How do sporophytes rise?
Two gametes unite to form a diploid zygote
Heteromorphic vs isomorphic alternation of generation
Some are Heteromorphic- sporophytes and gametophytes are structurally different
Others are Isomorphic generation- sporophytes and gametophytes look similar
What are alveolates, and what do they include?
Possess alveoli- membrane-encolsed sacs under the plasma membrane
Includes dinoflagellates, apicomplexans, and ciliates
What two things do dinoflagellates possess, how do they get nutrition, and what do they cause?
Possess cells reinforced by cellulose plates
Possess two flagella
Half are purely heterotrophic
Includes phytoplankton
Blooms cause red tides
Produces toxins that kill fish
What are apicomplexans, what do they possess, and an example?
Animal parasites
Spread infectious cells called sporozoites
Apex- one end Containing complex organelles specialized in penetrating host cells
malaria
What is malaria, how did it evolve, and where does it live?
caused by mosquitoes carrying Plasmodium
Plasmodium evolved to form resistant varieties
Lives in cells, not identified by the immune system
What do ciliates possess, what do they eat, how do they vary genetically, and how do they reproduce?
protists using cilia to move and feed
Possess a tiny micronuclei and a large macronuclei
Preys on bacteria and other protists
Conjugation
binary fission
What are rhizarians, and what do they include?
Subgroup for SAR clade,
amoebas
How do amoebas feed?
Pseudopodia, extensions bulgin from anywhere on the cell surface
What are radiolarians, and how is its psuedopodia reinforced?
Possess delicate, intricately symmetrical internal skeletons that are made of silica
Pseudopodia is reinforced by microtubules, covered in cytoplasm
What are forams, how do they gain energy, what do their pseudopodia do, and where are they found?
Possesses porous shells called tests
photosynthesis
pseudopodia- swimming, test formation, and feeding
marine ssediment, used to age sedimentary rock
What are cercozoans, how do they feed, and how do they get energy?
Amoeboid and flagellated protists
Feed using threadlike pseudopodia
Most are heterotrophs
Others are mixotrophs
Some are also autotrophs
What is archaeplastida?
Arose from an ancient protist that engulfed a cyanobacterium
What is red algae, why are they red, and how do they reproduce?
Most abundant large algae
Most aremulticellular
red due to phycoerythrin
reproduce sexually through alternation of generation
depends on water current to fuse gametes
What color is red algae and different depths?
Those in shallow water have less, being greenish red
Those in deep depths areblack
Some lack pigment and are heterotrophs
What do green algae possess, and what are they divided into?
Chloroplasts similar to land plants
Divided into charophytes and chlorophytes
What are charophytes?
Green algae closely rwlated to land plants
What three ways did chlorophytes evolve, and how do they reproduce?
Form colonies of individual cells to produce scum
Multicellular bodies form by cell division and differentiation
Repeated cell division of nuclei with no cytoplasmic division
Possess both sexual and asexual reproductive stage
What do unikonta include, when did it diverge, and what two clades are included?
Includes animals, fungi, and some protists
hypothesized to have diverged first
Two clades of amoebozonas and opisthokonts
Why is Unikonta controversial?
Which group diverge first is still unknown
What are amoebozoans?
Amoebas with lobe/tubee-shaped pseudopodia
What are slime modes, and what did they diverge into?
Aka mycetozoans
Once thought to be fungi
Diverged into plasmodial slime molds and cellular slime molds
What are plasmodial slime molds, their color, diet, and colony it forms?
Brightly colored, often yellow or orange
Forms a mass called plasmodium
Unicellular
Feeds on moist soil, mulch, and rotting logs
How do cellular slime modes function? (3)
During the feeding stage, cells function individually
When food is depleted, they function as a unit
Cells in the stalk die as they dry out, while spores on the top survive and reproduce
What are tubulinids, and how do they obtain energy?
Group of amoebozoans with lobe/tube-shaped pseudopodia
Most are heterotrophs
What are entamoebas?
Parasitic amoebas
What do opsithokonts include?
animals, fungi, and protists
What are two examples of symbiotic protists?
Photosynthetic dinoflagellates provide food for coral polyps
Wood-digesting protists inhabit gut of termite species
Two important roles of protists in habitat
as symbiont and as a producer
What are producers?
organisms that use energy from light, converting CO2 to organic compounds
How impactful are photosynthetic protists?
30% of the world’s photosynthesis is performed by protists
20% by prokaryotes
What do rising sea surface temperatures do? (3)
reduce marine producers
Producers rely on nutrients brought from upwelling
Warm water prevents upwelling
