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microbiology > protists structure and environment > Flashcards

protists structure and environment Flashcards

1
Q

protozoan

A

single celled microscopic animal of a group of phyla of the kingdom protista, such as an amoeba, flagellate, ciliate or sporozoan

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2
Q

definition of a protist

A

is any eukaryotic organism that is not an animal, plant or fungus. The protists do not form a natural group, or clade, but are often grouped together for convenience, like algae or invertebrates.

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3
Q

microtubules are known as

A

conserved structures

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4
Q

what are microtubules made up of

A

alpha and beta tbuln

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5
Q

investigation of alpha tubular phylogeny shows that eukaryotic organisms can be divided into three classes:

A

1) animal parabasalids, plant-protists, and the diplomonads

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6
Q

role of microtubules

A

1) cell shape
2) chromosome movement and cell division
3) cell motility (cilia and flagella)

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7
Q

difference between flagella in bacteria and protists

A

in bacteria: energy from proton pump in membrane

in protists: energy rom ATPase dynein

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8
Q

microfilaments

A

another cytoskeletal structure

  • 7nm in diameter
  • polymers of actin
  • maintaining and chasing cell shape
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9
Q

6 main groups of protists

A 
Opisthokonts
Excavates
Archaeplastids
Amoebozoa
CCTH
SAR (stramenopiles, alvolates, rhizaria)
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10
Q

mitochondria in Opisthokonts

A

flattened cristae

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11
Q

mitochondria in Excavates

A

mitochondria discoba- lacking ‘classical’ mitochondria

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12
Q

mitochondria in Archeoplastids

A

plastids

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13
Q

mitochondria in Amoebozoa

A

mitochondria with irregular cristae

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14
Q

two ways in which protists feed

A

pinocytosis and phagocytosis

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15
Q

pinocytosis

A
  • the uptake of nutrients present in solution
  • characteristic of protists without a differential oral cavity
  • unlikely that dissolved nutrients are utilised by free-living protozoans
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16
Q

which organisms rely on diffusive transport of essential compounds across their plasma membrane- pinocytosis

A

parasitic protists

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17
Q

pinocytosis vesicles

A

pinosomes

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18
Q

phagocytosis

A

three strep: food capture, phagosome formation and digestion

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19
Q

organelles required for phagocytosis

A

cytosome, oral funnel, pharyngeal basket

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20
Q

two types of phagocytosis

A

filter feeders and gulpers

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21
Q

filter feeders

A

paramecium and vorticella

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22
Q

two types of gulpers

A

vegetarians and predators

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23
Q

vegetarian gulpers

A

Chilodonella and Pseudomicrothorax

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24
Q

predator gulpers

A

Actinophrys and Homalozoon

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25
Q

filter feeding

A

suspended particles are concentrated through the actin of flagella or cilia in areas where endocytosis can take place.

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26
Q

how are flagella and cilia useful during filter feeding

A

direct a current of water to the cell and especially in ciliated towards a filter device

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27
Q

what special organelles allow ‘gulper’ protists to obtain food

A

extrusomes

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28
Q

extrusomes

A

membrane bound structures ins one eukaryotes which, under certain conditions, discharge their contents outside of the cell

29
Q

which the organelles like extrusomes are used to obtain food

A

toxicysts

30
Q

toxicysts

A

toxycysts filemtns carry a poison that can kill other protozoa.
- odd because they eat ciliates which should be able to swim away

31
Q

process of gulping

A
  • yeast cell taken in
  • food vacuole forms around yeast cell
  • vacoule becomes acidic
  • alkalinity re-established
  • waste material expelled
32
Q

cytopharyngeal baskets

A

a circle of trichites that reinforces and stiffens the gullet of various predaceous ciliates.

33
Q

other energy generating mechanisms (not mitochondria)

A

hydrogenosomes

34
Q

hydrogenosomes

A

lack cristae and the TCA cycle

  • present in aerobic protists
  • metabolism is fermentative
  • oxidation of pyruvate
35
Q

where are hydrogenosomes found

A

in anaerobic protists

36
Q

where does energy come from in hydrogenosomes

A

oxidation of pyruvate

- NO TCA cycle

37
Q

the eyespots

A

a photoreceptive organelle which through photoreceptor proteins causes flagellar to move through signal transduction

38
Q

what can be utilised to direct flagellar

A

the eyespot

39
Q

what is a significant problem for ciliates and many freshwater protozoans

A

they are hypotonic, therefore removal of water crossing the cell membrane by osmosis is a significant problem. one commonly employed mechanism is a contractile vacoule

40
Q

which organelle is used to remove water from cells

A

the contractile vacuole

41
Q

how does the contractile vacuole work

A

1) canals on the outside of the CV take up water from the cytoplasm
2) water moves from canals to vacuole
3) CV becomes full
4) Pore opens and vacuole contracts
5) contraction of vacuole expels water from the cell
6) empty vacuole

42
Q

how to protists sense

A

eyespot

43
Q

where are eyespots found

A

in flagellate cells of green algae and other unicellular photosynthetic organisms e.g. euglenids

44
Q

which protists provide 80% of coral energy needs via photosynthesis

A

Zooxanthellae- also takes up nutrients released by the coral metabolism such as nitrogen and carbon dioxide

45
Q

zooxanthellae

A

symbiont dinoflagellate protists that live within hard or stony coral e.g. Symbiodinium

46
Q

Zooxanthellae provides….. and the coral provides….

A

zooxanthellae produces photosynthesis produce and the coral produces CO2 and shelter

47
Q

bleaching in coral symbiodinium causes

A

death

48
Q

why may coral reef bleaching occurs

A
  • change in water temp
  • oxygen starvation caused by zooplankton
  • increases sedimentation
  • bacterial and fungal infection
  • changes in salinity
  • herbicides
  • low tide and UV exposure
  • elevated sea levels due to global warming
49
Q

abundance of protists in marine and terrestrial environments is

A

a guessing game

50
Q

colonisation of zooxanthellae by Dino’s

A

hypothesis: bleached coral can acquire new photosynthetic endosymbionts from their environment
conclusion: corals can recover Symbiodinium zooxanthellae from environment

51
Q

most abundant protists

A
  • Heteroloboseans
  • Gliding Bodonids
  • Glissomonads
52
Q

least abundant protists

A
  • Leptomyxa
  • Lopopod transparent testate amoebae
  • Apusomonads
53
Q

dealing with stress: starvation

A

between cell mechanism.
One cell begins to secrete cAMP in response to starvation. Other cells detect this signal and respond in two ways:
1) the cell over towards the signal
2) the cell secretes more cAMP to boost the signal

54
Q

modes of multicellularity -within cell mechanism

A

1) cAMP detection at the cell membrane activates G protein
2) G-protein activation stimulates Adenylate cyclase
3) cAMP diffuses out into medium
4) internal cAMP inactivates the external cAMP receptor
5) a diff G protein stimulates phospholipase C
6) IP3 induces calcium ion release
7) calcium ions act on the cytoskeleton to induce the extension of pseudopodia

55
Q

why does the cAMP conc show oscillatory behaviour

A

because the internal cAMP conc inactivates the receptor for external cAMP

56
Q

best protist predators

A
  • euglena spirogyra
  • aserionella formosa
  • amoeba proteus
  • nitschia sp
  • Blepharisma sp
57
Q

how many genera of Dinoflagellates are bioluminescent

A

18- majority editing blue-green light

58
Q

bioluminescence comes from

A

SCINTILLONS

59
Q

Scintillons

A

where bioluminescence comes from. Distributed in the cortical region of the cells as off-shoots of the main vacoule

60
Q

what regulates scintillions

A

circadian clock

61
Q

what is the main enzyme involved in luminescence in dinoflagellates?

A

Dinoflagellate luciferase

62
Q

Dinoflagellate luciferase

A

with luciferin, a chlorophyll derived tetrapyrrole ring acting as a substrate to the light producing reaction

63
Q

luminescence in dinoflagellates

A

produced by dinoflagellate luciferase

  • 0.1s blue flash
  • max 476nm
64
Q

what causes luminescence in dinoflagellates

A

a mechanical disturbance

65
Q

why are CVs needed

A

in freshwater environments, the conc of solute inside the cell is higher than the side of the cell (outside is hypotonic). Under these conditions waters goes from the outside into the cell. The CV is a protective mechanism that prevents the cells from absorbing too much water and lysing.

66
Q

the stage in which water flows into the CV is called

A

DIASTOLE (1-2s)

67
Q

the contraction of the CV and the expulsion of water out of the cell is called

A

SYSTOLE

68
Q

what are the structures attached to the CV called

A

SPONGIOME

-together called the contractile vacuole complex- CVC

69
Q

example of where protists come to the resuce

A

Kneallhazia solenopsae is a pathogenic intracellular microsporidium that infects two invasive fire ant species in N and S america. Gradually introduced from such america to Alabama in 1918

microbiology (25 decks)

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