Flashcards in Chapter 11: Unicellular Eukaryotes- Protozoan Groups Deck (66):
Unicellular eukaryotes are the major cause of?
lack cell wall
at least one motile stage in life cycle.
most ingest their food
carry all life activities in a single cell
survives only in narrow environment ranges
a close prolonged association between two or more different organisms of different species.
both species benefit in the relationship
benefits one but the other is not harmed
1 benefits and another is harmed
protozoa obtain organic molecules synthesized by other organisms
feed on visible particles
feed on soluble foods
Mode of nutrition for unicellular organisms is often ?
variable and opportunistic
no germ layers
no organs and tissue, just organelles
varied forms of nutrition
varied forms of locomotion
asexual and or sexual reproduction
Types of locomotion?(3)
cilia, flagella and pseudopodia
Cilia and Flagella
morphologically the same but cilia is smaller whereas flagella is long...more tail like
endo- contains nucleus and cytoplasmic organelles
ecto- more transparent (hyaline)
contains bases of cilia or flagella
Types of Pseudopodia- Offer descriptions of each:
1. large blunt extensions of the cell body containing both endo and extoplasm.
2. thin extensions usually branching and contain only ectoplasm.
3. repeatedly rejoin to form a netlike mesh...which makes it distinguishable from filopodia.
4.long, thin pseudopodia supported by axial rods of microtubules which are organized in a spiral or geometrical array....which can be extended or retracted via addition or removal of microtubules..progression via rolling motion aka....retraction of front and extenuation of the back...cytoplasm can flow along axonemes.
movement of the entire body via pseudopodial movement...not individual movement of each extension.
Describe the process of pseudopodial movement. (theres a lot to know)
endoplasm? myosin? actin??....
endoplasm flows into / toward the hyaline cap (ectoplasm extension) which contains actin subunits attached to regulatory ABPs which prevent actin from polymerizing...As the endoplasm flows and spreads to the periphery..interactions between phospholipids in the cell membrane causes the release of actin from their ABP allowing them to polymerize into actin filaments...which are cross linked via ABP causing the ectoplasm to become a tube with which the endoplasm can flow through as the pseudopodium extends. The trailing edge contains calcium ions that activate the release of ABP which releases the actin filaments permitting myosin to associate with and pull these filaments...causing contractions...creating a pressure that causes the endoplasm to flow back to the hyaline cap.
Excretion and osmoregulation is done via??(2)
Excretion of metabolic wastes is by diffusion...end product = Ammonia
Contractile Vacuoles- fill up and empty to maintain osmotic balance....water enters via osmosis.
Why do fresh water species have more contractile vacuoles and occur more frequently vs marine species??
Marine species cytoplasm is nearly isotonic to that of the marine environment...whereas freshwater species are hypotonic to their environment and continually need to expel water or else they would fill up and burst..
What are the three types of asexual reproduction found in unicellular organisms?
produces more individuals than other forms of production......binary fission is the most common...two identical individuals are produced via splitting of the cell..
occurs when a small progeny cell (bud) pinches off from the parent cell and grows to adult size. **mostly ciliates
Multiple Fission?? (Schizogony)
Cytokinesis preceded by several nuclear divisions....thereby many individuals are produced simultaneously ...
if the union of gametes precedes multiple fission or associated this occurs.
gametes look alike
gametes are dissimilar...characteristic of most species
may occur during or just before gamete formation(seen in animals) .....(in other groups meiosis occurs after fertilization...zygotic )
-all individuals produced asexually in life cycle up to next zygote are haploid!
fertilization of one gamete by another
Gamete nuclei form by meiosis and fuse to form a zygote inside the parent organism
gamete nuclei exchange between paired organisms
During division what occurs to the macronucleus and micronucleus?
macro - undergoes mitosis
micro- just divides into two
formation of a cyst...dormant forms that shut down metabolism and have a resistant external covering secreted by the golgi aparatus...this is rare or absent in marine forms.
escape from cyst once the environment is more favourable
Trichomonas vaginalis (3)
infects the urogenital tract of humans
irritation, burning and discharge
Important parasitic genus ?
holozoic or saprozoic nutrition
important genus of protozoan parasites some are not pathogenic
T. brucei gambiense and T.b. rhodesiense ?
African sleeping sickness in humans ...animals that carry it before humans contract it are not sick, they show no symptoms
T. brucei brucei ?
causes african disease type disease in domestic animals
causes Chagas' disease
All three of the trypanosoma protozoans are carried by?
testse flies.....aka kissing bug
parasitic, free living?
ciliates are the most diverse and specialized protozoans
larger than most
mostly free living, some commensal and parasitic...
usually solitaire and motile
most free living are in freshwater or marine
Ciliophora (under phylum cliliophora)
multinucleate - at least one macro and a micronucleus qqq
metabolic and developmental functions
involved in sexual reproduction and give rise to macronuclei afterwards..
-only genes of the micro are transcribed.
germ line nucleus
Symbiotic Ciliates ?
live in the intestine of many animals including humans, pigs, rats and many other mammals and vertebrates
not usually pathogenic
causes the fish disease ick.
Phylum Dinoflagellata ?
mouth yes/no? for?
around 1/2 are photoautrophic
chloroplasts possibly acquired via endosymbiosis
primary producers in marine environment
two flagella usually
body is naked or covered by cellulose plates
mouth region through which they ingest prey
many are bioluminescent
ex: zooxanthellae - live in mutualistic association with corals and other inverts...provide nutrients to the coral ....
Phylum Apicomplexa ?
-hosts are in many animal phyla , pseudopodia occur in some stages, gametes may be flagellated
-life cycle usually includes both sexual and asexual stages...invertebrates may be an intermediate host..
-during life cycle: forms a spore (oocyst),,,infective in the next host, protected via coating.
Taxoplasma gondii ( phylum apicomplexa)
-reproduction occurs where?
- contracted from?
-parasite of cats, rodents, cattle and humans
-cross the intestine and asexually reproduce in tissues
-from eating undercooked meat
-serious problem during pregnancy- slowed mental growth
Plasmodium: The malarial Organism??
-amount of species?
-type of Mosquitos?
-female injects what?
-sporozoites penetrate what?
-four species infect humans
-each produces different clinical symptoms
-anopheles mosquitoes are the only type thar carry malaria
-female injects plasmodium thats in her saliva
-sporozoites penetrate liver cells and initiate schizogony
-microgametocytes- can only survive in the circulatory system for so long.
what do they lay down?
most live on the ocean floor
largest biomass of any animal group
most tests are many chambered and made of calcium carbonate
1/3 of the sea bottom is covered with foraminiferous ooze.
-limestone and chalk deposits have been laid down by foraminiferan accumulations
Radiolarians (phylum Foraminifera)
-marine testae ameba with intricate skeletons
-pelagic and live in shallow water
-shell surface is fused with spines
-cytoplasm around the capsule extends axopodia to catch prey
-reproduce via binary fission, budding and sporulation
-helps in determining the age of rock strata...
-types of amebas?
-naked and testate amebas as well as those with flagellated life stages
-Amoeba castellani kills cells of the human cornea ...spread bu contact lenses that are not disinfected
-Entamoeba histolytica - lives in large intestine of humans, invade the intestinal wall by secreting enzymes that attack the intestinal lining, can lead to amebic dysentery?
What is Amebic Dysentery?
inflammation of intestines, nausea, and diarrhea. Acquired via ingestion of Entamoeba histolytica
amebas that make shells....plasma membrane is covered with a protective test or shell of secreted siliceous or chitinoid material.
amebas without a test
tube of microtubules in a flagellum or cilium.... covered by a membrane continuous with the cell membrane
Kinetosome? (basal body)
identical in structure to centrioles that organize mitotic spindles.....contains nine triplets of microtubules where the flagellum enters the cell body.
Sliding Microtubule Hypothesis?
movement is powered by a release of chemical bond energy...atp....two arms of dynein proteins....atpase cleaves atp..causing them to walk along microtubules in the adjacent pair.
organelles that perform respiratory function in the absence of oxygen..derived from the mitochondria .
ex: strands that cause African sleeping sickness!!
contain masses of circular DNA and work in association with a kinetosome...which is at the base of a flagellum.
participates in cellular secretory processes and intracellular digestion of ingested food vacuoles.
contain photosynthetic pigments
chloroplasts contain chlorophylls a, b and c.
membrane bound organelles that extrude something from the cell..
small bodies in their ectoplasm between the bases of the cilia.
expel a poison to subdue prey via mechanical or chemical stim...
carnivorous ciliates have this....
Phylum Euglenozoa ?