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zoology > Unicellular Eukaryotes > Flashcards

Unicellular Eukaryotes Flashcards

1
Q

How do we define eukaryotes

A 
single celled
- impact life by causing disease etc
- highly adaptable and require moisture
- represent all symbiotic relationships
- form paraphyletic group
- have specialized organelles
-
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2
Q

How do eukaryotes impact human life

A
  • cause disease such as malaria an dysentary
  • infect livestock
  • our ability to classify them determines our ability to treat the diseases they cause bc susceptibility to drugs is often lineage dependent
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3
Q

Give examples of symbiotic relationships between eukaryotes and other organisms

A
  • commensalistic -
  • parasitic -
  • mutualistic -
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4
Q

Characteristics of Eukaryotes

A
  • unicellular (colonial, some have multicellular life cycle stages)
  • mostly microscopic
  • all symmetries are represented
  • no germ layer
  • specialized organelles, multiple or single nucleus
  • locomotion by cilia, flagella, or pseudopodia
  • some sessile
  • free-living, mututalistic, parasitic, and commensalistic
  • some have endoskeleton, some exoskeleton, but most naked
  • autotrophic, heterotrophic, saprozoic, and holozoic feeding
  • aquatic or terrestrial
    reproduce asexually by fission, budding or cysts or sexually by conjugation or syngmamy
  • some have developed multicellularity and have somatic and sex cells like the volvox carteri
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5
Q

describe the functional components of protozoa

A

nucleus: houses DNA and communicated through cytoplasm instructions for function of other organelles
Mitochondria: metabolize O2 into energy and sontain cristae which is a diagnostic features for many eukaryotes
Golgi : secretory system
Plastids: contain photosynthetic pigments
Extrusosomes: membrane-bound organelles used to extrude something from the system

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6
Q

name for locomotor organelles

A

undulipodia

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7
Q

compare cilia and flagella

A

cilia move the organism by propel water parallel to the surface to which it was attached and appear in large numbers and are short
Flagellum propel water parallel to the axis of the flagellum and they are longer and less numerous
Their internal skeleton, however, is a commonality

Both create water currents for feeding and respiration, excretion reproduction and osmoregulation

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8
Q

describe the internal skeleton of the undulopodia

A

there are nine pairs of longitudinal microtubules arranged around a central pair. - this tube is called an axoneme. the axoneme is covered with a membrane continuous with the rest of the organism. when the axoneme enters the cell proper the central pair of microtubules stop at a plate within the circle of nine pairs. at this point another microtubules joins the nin pairs and the pairs are called the kinetosome or basal body.

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9
Q

chief form of locomotion for amebas and function

A

pseudopodia: temporary extensions of cytoplasm that function in locomotion and ingestion - usually found in amoebas or ameboid cells

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10
Q

what are the two states most common pseudopodia, lobopodia can be found in

A

endoplasm: in a fluid state
ectoplasm: in a gel or colloid state

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11
Q

Axopodia, Filipodia, Reticulopodia, lobopodia

A

long, thin pseudopodia supported by axial microtubules and can be extended or retracted by the addition or removal of microtubules materials

thin extensions, usually branching, containing only ectoplasm, that ocurr in amebas such as Chlamydophrys

repeatedly join to form a net-like mesh

large blunt extensions of the cell body with endoplasm and ectoplasm

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12
Q

how to pseudopodia formed

A

when a lobopodium starts to form and extension of the ectoplasm - hyalin cap - appears. As endoplasmic material flows through the hyalin cap in beings to fountain out, changing form a liquid to semi-solid form and becomes the ectoplasm. in the front of the organism the ectoplasm is a tube through which endoplasm flows as the pseudopodium extends. on the back side the ectoplasm becomes endoplasm then at some point the pseudopodium becomes anchored to a substrate and the organism is moved forward

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13
Q

what structures are present in protozoa without mitochondria

A

hydrogenosomes: produce ATP from hydrogen when O@ is not present - mitochondrial derivative

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14
Q

current hypothesis of pseudopodial movement

A

As the endoplasm fountains out in the hyalin cap, Actin subunits becomes polymerised into microfilaments which becomes cross-linked together by actin-binding protein to form gel - the endoplasm becomes the ectoplasm. At the posterior end the ABP releases microfilaments which return to the liquid (sol) state of the endoplasm. before the microfilaments disassemble they interact with the myosin contracting and causing the endoplasm to flow in a direction of the pseudopodium by hydrostatic pressure

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15
Q

Describe nutrition and digestion of protozoa

A

autotrophs - synthesise their own food - these usually contain plastids and use photosynthesis
heterotrophs - obtain organic material synthesised by other organisms
Of the heterotrophs their are two subgroups
- phagotrophs which are holozoic feeders meaning they ingest food particles
- osmotrophs which are saprozoic feeders meaning they ingest their food in soluble form

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16
Q

describe holozoic feeders

A

holozoic feeding involves phagocytosis which is when a food vacuole is formed around the food particle as it inters the cell at the cytostome. Lysosomes fuse with the vacuole and secrete digestive enzymes. digestion begins and the products are absorbed across the vacuolar membrane - the phagosome becomes smaller and smaller and the indigestible material is extruded out of the cell where the vacuole fusing back into the membrane by the cytoproct. -

17
Q

function of contractile vacuoles in protozoa and in what forms of protozoa are they found

A

Found in fresh water protozoans such as ameba and paramecium, the contractile vacuole, acts as pumps to remove excess water from the cytoplasm through a process called osmoregulation. prton pumps on the vacuole surface and on tubules connected to it transport H ions and bicarbonate ions. As these ions accumulate within the vacuole, water is drawn into the vacuole. Then the vacuole joins its membrane with the surface membrane and expels water, H ions and bicarbonate ions. These ions are readily replaced by carbonic anhydrase in the cytoplasm.

18
Q

name the processes of asexual reproduction in uni euks

A

binary fission
budding
schizogony (multiple fission)
sporogony

19
Q

binary fission process

A

form of asexual reproduction for unicellular organisms in which the parent organism splits in half and produces two identical daughter cells - can be irregular like in the amebas , fixed like in flagellar organisms like euglena, and schizogony like in paramecium

20
Q

process of budding

A

occurs when a small progeny cell pinches off from the parent cell

21
Q

schizogony

A

multiple fissions at the same time - cytokinesis preceded by multiple nuclear divisions

22
Q

value of encystment and excystment

A

in order to survive under harsh conditions eukaryotes form cysts in which a number or organelles are resorbed and the Golgi secretes a cyst wall material around them which is carried to the surface of the vesicles and extruded - conditions that stimulate encystment could be environmental conditions, food deficiency, low O2 in atmosphere, and change in pH - when conditions get better excystment occurs.

23
Q

Phylum Eugelnozoa characteristics and taxonomy

A

Phylum Euglenozoa characterized by pellicle, flagella, w paraxial rod, mitochondrion with discoid cristae, nucleoli persist during mitosis

  • —–Suphylum Euglenida : pellilcular microtubules that stuffen pellicle
  • ———–Class Eugleniodae: two flagella, some spieces with stigma and chloroplasts
  • ——————-Genus Euglena

Subphylum Kinetoplasta: unique mitochondrion with large disc of DNA, paraxial rod

  • —–Class Trypanosomatidae : 1 or 2 flagella, single mitochondrion, extending the length of the body as a tube, hoop, or network, usually with kinetoplasts containing DNA located near flagellated kinetostomes; all parasitic
  • ————–Genus Leishmania and Trypanosoma brucei (African Sleeping Sickness )
24
Q

Phylum Ciliophora

A

-called ciliates
- freshwater and marine
- most complex of all unicells
- larger than most other Protozoans
- may be solitary and motile or colonial and sessile
some forms have undulating membrane others have
smaller structures both propel food into the
cytopharynx
- Kinetosomes and fibrils under then pellicle form
infraciliature
- some ciliates have toxocysts which when stimulate the
shoot out and release poison which paralyse their prey
- multinucleate
macronucleus has developmental functions while the
micronucleus (2n) controls sexual reproduction and
gives rise to a second macronuclei after exchange of its contents
rise to another micronucleus during division
- holozoic, possess cytostome
- contractile vacuole
-examples are Paramecium, Vorticella, Trichodina, Stentor Zoothamnium (colonial)

25
Q

conjugation

A

a type of sexual reproduction that occurs in ciliates which involves the temporary joining of two individuals for the purpose of exchanging chromosomal material

26
Q

Binary fission in paramecium

A
  1. micronucleus begins mitosis
  2. macronucleus begins elongation
  3. Bud appears on the cytostome
  4. micronucleus divides
  5. macronucleus divides into two pieces
  6. new cytopharynx forms from bud
  7. two new contractile vacuoles appear
  8. division of cell body is complete
    Results in two identical daughter paramecia
27
Q

Conjugation in Paramecium

A

This form of reproduction occurs when organisms start to become weak due to too many binary fissions.

  1. two paramecium of different mating types come into contact by their oral surface
  2. the 2n micronuclei divide by meiosis to produce four n micronuclei then the macronuclei degenerate
  3. three micronuclei degenerate and the remaining micronucleus in each individual divides to produce one male and one female pronuclei
  4. male prouclei are exchanged between conjugates
  5. male and female pronuclei fuse to make 2n nucleus then the individuals separate
  6. three sets of mitotic divisions produce 8 micronuclei - four of these become the macronuclei while three degenerate
  7. the remaining micronucleus divides twice, as does the cell,
    Result is 4 daughter cells
28
Q

Phylum Ameobozoa

A
  • their are naked and shelled amebas, many with
    flagellated stages in their life cycles
  • mitochondria, when present, have tubular cristae
  • free-living and parasitic
    examples are Ameba proteus, Entamoeba histolytica which causes amebic dysentary in humans
29
Q

Phylum Radiolaria

A

most are amebas with well developed internal skeletons of strontium sulfate or silica, forming beautiful shells
axopodia are present
- examples are Tetrapyle and Pterocorys

30
Q

Phylum Dinoflagellata

A 
autotrophic 
commonly have two flagella 
naked or covered with cellulose plates 
mouth region for ingesting food 
bioluminescent
produce RED TIDE
release toxin in their cells that when consumed by feeders like molluscs is not harmful but whne a human consumed the mollusc tissue the toxin can cause numbness, paralysis, and often death
31
Q

what is red tide

A

Red Tide is caused by the release of a toxin in the water during profuse reproduction of the Zooxanthellae called bloom producing. This toxin may turn the water red, brown or yellow. It is harmful to other organisms in the water.

32
Q

Phylum Apicomplexa

A

these Phyla are parasites with their hosts being in many animal phyla
their life cycle involves sexual, asexual, and sometimes intermediate hosts which are always vertebrates
Apical Complex is a distinguishing feature - usually occurs only in certain life cycle stages - merozoites
- Rhoptries and Micronemes aide in penetrating hosts cell
–Class Gregarinea: parasites of digestive tract or body cavity of vertebrates
–Class Coccidea: intracellular, parasites of vertebrates or invertebrates
—-Genus - Cyclospora, Toxoplasma, Plasmodium etc

33
Q

Structures of the Apical Complex

A 
Polar ring 
Conoid
Subpellicular microtubules
Micronemes 
Rhoptry 
Micropore
34
Q

Phylum Radiolaria

A

marine ameba with intricate skeletons
oldest known protozoa
mostly lives as plankton
has sticky axopodia to capture prey

35
Q

Life Cycle of Plasmodium Vivax

A

Vector is Female Aniopheles mosquito and it carries plasmodium vivax which causes malaria
mosquito ingests gametocytes and fertilisation occurs by sporogony to produce the sporozoites –
–then sporozoites are released into the salivary glands of the mosquito– mosquito injects saliva into intermediate host human where the sporozoites travel through the blood stream to the liver–while in the liver cells the sporozoites undergo schizogony in which sporozoites multiply and become merozoites which then shed into the blood stream once the liver cell ruptures—
—once in the blood stream the merozoites infect the erythrocytes and develop into the trophozoite stage —
the trophozoite undergoes division and produces more merozoites— the RBC then lyse and the rest of the blood cells continue this process until they are all infected— some merozoites develop into macrogametocytes or microgametocytes —another mosquito bites this infected human and the cycle starts again

zoology (2 decks)

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