Eukaryotes Flashcards
Features of eukaryotes
Organized nucleus –Linear chromosomes –Membrane-bound •Organelles –Mitochondria –Chloroplasts –Diges(ve vacuoles
Membranes, Cytoskeleton
Organelles: membranes associated with specialized func(ons •Vesicles: move materials out of cell, into cell •Movement relies on cytoskeleton –Preda(on –Change shape –Increased size
Energy metabolism
Stable membranes •Chloroplast, mitochondria •Endosymbiosis origins •Eukaryotes con(nue to enjoy symbio(c rela(onships with prokaryotes
Chromosomes and Sex
Linear DNA molecules –Mul(ple origins of replica(on –Large molecules- carry many genes, regulatory regions •All eukaryotes have a sexual life cycle (or used to: ro(fers) •Meiosis –Gametes have ½ the normal chromosome number- meiosis- special cell division •Fusion of gametes: “fer(liza(on” •Sex increases diversity •Life cycle varia(ons: diploid, haploid phases can be persistent or brief –Depends on (ming of meiosis, fer(liza(on
super kingdoms
Plants •Animals and Fungi
•Pro(sts–Usually single-celled –Diverse, polyphyle(c –Many niches –Move by flagella, cilia, or pseudopods –Single cells can be complex!
Opisthokonts
Flagellum is posterior, single
Animals (mul(cellular)-Fungi (uni- or mul(cellular) -choanoflagellatesChoanoflagellates can be colonial- a first step toward mul(cellular
Fungi- Opisthokonts
Fungi Cell wall of chi(n Muul(cellular or unicellular (e.g. yeast) Absorp(ve heterotrophy Enzymes are secreted, break down food, absorbed Fungi can feed on living, dead organisms Fungal infec(ons in animals difficult to treat as many fungicides are also toxic to animal cells
Fungi- Opisthokonts
ingle-celled: “yeasts” •Mul(cellular: strands or hyphae •Mushrooms –Underground mycelium –Aboveground frui(ng body •Makes spores by meiosis •Play a major role in decomposi(on of dead organisms –During Carboniferous, fewer fungi, dead plants became coa
fungi help harm
Fungal infec(ons in animals •Plant pathogens: rusts, smuts •Symbiosis: mycorrhizalfungi- allow trees to take up more minerals from soil •Lichens: fungus + green algae (or cyanobacterium
Amboebozoans
use pseudopods for mobility
Amboebozoans- Amoeba –
a loboseanAqua(c (fresh water) Moves via pseudopods Eats via phagocytosis Predator, scavenger, or parasite
Amboebozoans- Physarum- a plasmodial slime mold
errestrial (forests) Disperse, then aggregate (coenocy(c) to form frui(ng bodies, where spores form by meiosis Scavengers, ingest by endocytosis Move by cytoplasmic streaming
Amboebozoans- Dictyostelium- a cellular slime mold
Amoeba-like single cells aggregate into a “slug” when dry or starved Cells are retained, form spores
Rhizaria (Roots)
unicellular aquatic, with long pseudopods, marines
Rhizaria- Foraminiferans
External shells of calcium carbonate Source of limestone Pseudopods ensnare plankton
Rhizaria- Radiolarians
Glassy endoskeletons Include some of the largest unicellular eukaryotes Can have photosynthe(c endosymbionts-dinoflagellates
Archaeplastids
Chloroplasts - 2 outer membrances
Archaeplastids
and plants (mul(cellular) RedalgaeMarine Photosynthe(c chlorophyll a, phycoerythrinGreen algae chlorophyll a, b (like land plants) uni- or mul(cellular mul(cellular- e.g. Volvox (freshwater) spheres of flagellated cells e.g. Sea le_uce (marine)
Stramenopiles
unequal flagella
Stramenopiles- Diatoms
silica in cell walls- upper and lower like a petri dish Aqua(c- fresh and salt Photosynthe(c-storage products oils Diatomaceous earth-filtra(on
Stramenopiles- Brown Algae
can be mul(cellular Sea palms, giant kelp Photosynthe(c chlorophyll a, c, + brown pigments Source of emulsifiers of ice cream
Green algae, land plants: chloroplast (cp) from cyanobacteriumendosymbiont
Enclosed by 2 membranes: one from cyanobacterium, one from host cell
Serial endosymbiosis: more than 2 membranes around cp
Brown algae, diatoms, dinoflagellates: 4 membranes Cp derived from red algae endosymbiont: inner 2 membranes from algal chloroplast next out from cell membrane of red alga outermost from host
Euglenids
cp from green algal endosymbiont
