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101 Cards in this Set

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What was (is) wrong with the kingdom Protista?
It includes everything that is not a plant, animal, or fungus, from ameobas to seaweed, and is paraphyletic (some members are more closely related to plants/animals/fungi than other protists).
How many cells do most protists have?
one
What describes protists that photosynthesize and act heterotrophically?
mixotrophic
What are the three types of protists nutritionally?
ingestive protozoa/n (like animals), absorptive protists (like fungi), and photosynthetic alga/e (like plants)
What is the difference between prokaryotic and eukaryotic flagella?
Prokaryotic flagella are attached at the cell surface, while eukaryotic flagella reach into the cytoplasm
Which kinds of reproduction do protists have?
asexual reproduction, mitosis in most, meiosis and syngamy
What are resistant protist cells (a part of their life cycle) called?
cysts
What is common to protistan habitats?
water
What roles do protists play in marine habitats?
They are benthic (bottom) dwellers and plankton, especially phytoplankton
What two eukaryotic organelles (in general) arose from endosymbiosis?
mitochondria and plastids
What does the theory of serial endosymbiosis say?
Mitochondria and plastids originated as prokaryotic endosymbionts within larger eukaryotic cells.
What is an endosymbiont?
a cell that lives within its host cell
Which evolved first, the endomembrane system or mitochondria and plastids?
the endomembrane system
Which evolved first, mitochondria or chloroplasts?
mitochondria
What evidence favors the endosymbiotic origin of membraned organelles?
endosymbiosis exists today; bacteria and membraned organelles are similarly sized, have similar membranes, replication, DNA, RNA, ribosomes, and antibiotic sensitivity.
What five things must a theory for the origin of eukaryotes account for?
the endomembrane system, mitochondria, the cytoskeleton, mitosis, and meiosis
Based on molecular systematics, what prokaryotes are most closely related to mitochondria?
α proteobacteria
Based on molecular systematics, what prokaryotes are most closely related to plastids?
cyanobacteria
Where are the genes coding for the proteins in mitochondria and plastids?
Some is in its own DNA, and some comes from the nucleus.
What theory attempts to explain the origin of plastids with more than two membranes in some algae?
Secondary endosymbiosis: The algal heterotroph digests another alga, creating extra layers.
What evidences have challenged the traditional "tree of life"?
Eukaryotes have bacterial DNA that is unrelated to mitochondria or chloroplasts, and archaea also have bacterial DNA.
What replaces the Last Universal Common Ancestor in the "web of life"?
a community of primitive DNA-exchanging cells
What still exchange DNA today?
prokaryotes
How are eukaryotic phylogenies reconstructed?
based on cell structure, life cycles, and molecular sequencing, including SSU-rRNA and some cytoskeletal proteins
What two groups of protists lack mitochondria?
diplomonads (Diplomonadida) and parabasalids (Parabasala)
What does the archaezoa hypothesis say?
Protists without mitochondria branched off before the endosymbiosis of mitochondria.
Why has the archaezoa hypothesis been rejected?
Mitochondrial genes were discovered in the genomes of protists lacking mitochondria.
What do diplomonads have?
multiple flagella, two nuclei, a simple cytoskeleton, and no membraned organelles
What is an example of a diplomonad?
Giardia lamblia, an intestinal parasite, causes abdominal cramps and severe diarrhea and is found in its dormant cyst stage in water contaminated with human feces.
What is an example of a parabasalid?
Trichomonas vaginalis, a trichomonad, inhabits the human female vagina, and can take over if the pH is changed. It has flagella and an undulating membrane.
What two groups make up the Euglenozoa clade?
the euglenoids and kinetoplastids
What do euglenoids usually have?
an anterior chamber, out of which 1-2 flagella emerge, and paramylon, a storage polymer of glucose
What is an example of Euglenophyta?
Euglena, a mixotrophic inhabitant of murky pond water
What do kinetoplastids have?
one mitochondrion with a unique kinetoplast organelle, which stores extra DNA
What is an example of a pathogen in Kinetoplastida?
Trypanosoma (genus) causes African sleeping sickness, carried by the tsetse fly, by changing its coat molecular structure frequently to prevent detection.
What does Alveolata consist of?
dinoflagellates, apicomplexans, and ciliates
What defines alveolates?
They all have small cavities in their cells with unknown function.
Where do members of Dinoflagellata live?
near the surface of water as phytoplankton and zooplankton
What do dinoflagellate blooms cause?
red tides (because that's the color of xanthophylls in dinoflagellate plastids); toxins can also be released in large quantities during red tides
What do dinoflagellates have in common?
They live in water, are unicellular (but can form colonies), have a top shape often reinforced by cellulose plates, and have two flagella spinning in an equatorial flagellar groove.
Which dinoflagellate is most dangerous?
Pfiesteria piscicida is carnivorous, stunning fish and feeding on their body fluids.
What are two additional properties carried by some dinoflagellates?
bioluminescence (to attract bigger fish to eat their predators?) and mutualistic symbiosis with reef-building cnidarians
What do apicomplexans do?
All are animal parasites; they send out infectious sporozoites that have an apex with a complex of organelles designed to penetrate host cells and also have intricate sexual and asexual life cycles.
What is an example of a member of Apicomplexa?
Plasmodium, which causes malaria, spread by Anopheles mosquitoes, which kills 2 million people per year.
What do ciliates have in common?
They all use cilia to move and eat, and most live alone in fresh water.
What properties do the cilia of ciliates have?
Cilia are shorter than flagella and cover ciliates in patches or in total.
How are ciliate genes stored?
Ciliates have a macronucleus with many copies of the genome not split into chromosomes as well as from 1 to 80 micronuclei.
What is the name of the group ciliates are in?
Ciliophora
How do ciliates reproduce?
asexual binary fission, with the macronucleus splitting without copying itself
How does Paramecium caudatum undergo conjugation and genetic recombination?
The micronucleus undergoes meiosis; one of the haploid daughters does mitosis, and one of those is traded with that of another cell, ending with syngamy when the two haploid copies fuse. This new micronucleus makes 8 copies, four of which become macronuclei while the original macronucleus breaks down. Two cell divisions leave the paramecium right where it started.
What do members of Stramenopila have in common?
Their motile reproductive stages have "hairy" flagella, each paired with a non-hairy flagellum.
What does Oomycota include?
water molds, white rusts, and downy mildews
What word describes cells with multiple nuclei?
coenocytic
What are water mold cell walls made of?
cellulose
What have a similar body plan as oomycotes?
fungi
What shape do oomycotes assume?
a cluster of thin filaments called hyphae, designed to absorb nutrients
What do water molds do?
Most decompose dead algae and animals in fresh water, but some are fish skin parasites.
What do white rusts and downy mildews do?
They are plant parasites that spore to the winds, but also make zoospores with flagella.
What are two examples of especially harmful oomycotes?
A downy mildew attacked vineyards in France in the 1870s, and Phytophthora infestans causes late potato blight, a part of the 19th Century Irish famine.
What do heterokont algae have in common?
Most are photosynthesizers, all have two different types of flagella, with hairs and without them, and they have a 3-membraned plastid.
What are the three types of heterokont algae?
diatoms, golden algae, and brown algae
What groups are diatoms in?
Bacillariophyta, within Stramenopila
How do water molds reproduce asexually?
Hyphae ends make zoosporangia, that make about 30 zoospores each, which form cysts and eventually grow into a body of hyphae.
How do water molds reproduce sexually?
Meiosis makes eggs in an oogonium while other branches make sperm nuclei in surrounding antheridial hyphae, which fertilize the eggs, making oospores. The oospores develop into zygotes and make zoosporangia, releasing zoospores.
What are diatom walls made of?
hydrated silica within an organic matrix
How do diatoms usually reproduce?
Asexually: Each daughter receives the top or bottom half of the shell and builds the missing half.
How do diatoms store food?
as the glucose polymer laminarin and oil
What do golden algae have in common?
Yellow and brown carotene and xanthophyll color them; they usually have two flagella close to each other; they live as plankton; they are unicellular, and possibly mixotrophic and/or colonial
What groups are golden and brown algae in, respectively?
Chrysophyta and Phaeophyta
What do brown algae have in common?
All are multicellular, most marine, live in temperate zones, many seaweeds are brown algae.
Are seaweeds and plants analogous or homologous?
analogous
What structures in seaweeds are analogous to plant structures?
thallus = plant body, holdfast = roots, stipe = stem, and blades = leaves
What are kelps?
giant brown algae (seaweeds) that live in deep water
Why are seaweeds slimy?
Seaweed cell walls are made of cellulose plus algin (brown algae) or agar and carageenan (red algae), to cushion them against the waves.
What do humans use seaweed for?
Asians eat it (Laminaria in soups, Porphyra in sushi) because it has iodine and other minerals, but many of its polysaccharides are undigestible. Algin, agar, and carageenan are used in processed foods, lubricants, and microbe cultures.
What does alternation of generations mean?
There are two multicellular stages, one haploid and one diploid.
How does alternation of generations work?
Sporophytes are diploid, and make zoospores in their sporangia by meiosis. The zoospores become haploid gametophytes, half male and half female, which fertilize to make a new sporophyte.
Are the two types of generations in alternation of generations different?
Sometimes: If so, they're heteromorphic; otherwise, they're isomorphic.
What's special about red algae?
They don't have flagella—ever—and are red because of phycoerythrin, a phycobilin, also in cyanobacteria. Also, they are the most abundant large algae, aren't always in the ocean, and can live at depth because of their ability to absorb blue light.
What protists are most closely related to plants?
Chlorophyta, or green algae
How has complexity and larger size evolved in chlorophytes?
as colonies of individual cells (Volvox), by nucleus division without cytoplasm division (Caulerpa), and by cell division and differentiation (Ulva)
What are amoebas?
members of Rhizopoda (root-like feet), unicellular protists that use pseudopodia
What are pseudopodia?
cellular extensions that assist in movement and feeding
How does pseudopodium movement work?
A pseudopodium extends from the cell surface, anchors somewhere, and fills with cytosol, moving the protist. The cytoskeleton accomplishes all of this.
Where do ameobas live?
in water and soil, and some are parasites such as Entamoeba histolytica which causes amoebic dysentery
What are the two types of actinopods?
heliozoans and radiolarians
What do actinopods have in common?
They all have at least one axopodium, a thin pseudopodium with lots of microtubules; they have silica skeletons, and phagocytize prey using their axopodia.
What is the difference between heliozoans and radiolarians?
Heliozoans have silica or chitin plates that aren't fused together, while radiolarians have one connected silica skeleton. Also, heliozoans are primarily freshwater, while radiolarians are mostly marine.
What do forams have in common?
Foraminiferans are marine creatures, mostly benthic, that have holey CaCO3 shells with pseudopodia sticking out.
What's special about forams?
90% of species are fossils, so they make marine sediments and help date sedimentary rock
Name the three taxons that use pseudopodia.
Rhizopoda, Actinopoda, and Foraminifera
What taxon are slime molds in?
Mycetozoa
What do slime molds have in common?
They use pseudopodia, are relatively closely related to fungi and animals, and try to maximize food contact.
What are the two kinds of slime molds?
plasmodial and cellular
What taxon are plasmodial slime molds in?
Myxogastrida
What structure does a feeding plasmodium have?
one supercell as big as several centimeters with a bunch of nuclei that do mitosis together
Other than structure, what do plasmodial slime molds have in common?
They are bright yellow or orange, have cytoplasm streams flowing every which way, eat by phagocytosis and extending pseudopodia
Describe the life cycle of a plasmodial slime mold.
When the going gets tough, a mature plasmodium makes sporangia that stick out from its surface and release resistant spores that develop into flagellated or ameoboid haploid cells, which come together at syngamy to make a new zygote plasmodium.
What taxon are cellular slime molds in?
Dictyostelida
What is different about cellular slime molds as opposed to plasmodial slime molds?
Cellular slime molds are separated by their membranes (still functioning basically together), are almost always haploid, do not have flagella and can reproduce asexually.
How many times did multicellularity arise?
many times