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BIOL 121 - Impact Of Microbes > Protists > Flashcards

Protists Flashcards

1
Q

What are protists

A

All eukaryotic cells: most live alone but they can form colonies

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2
Q

What is a cytoskeleton organelle?

A

Organises other organelles within the cytoplasm

Components include: actin filament, microtubule, intermediate filament

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3
Q

Three types of protists are:

A
  • Photoautotrophic (photosynthesise, usually termed algae (general term for photosynthetic organisms)
  • heterotrophic (feed on bacteria, fungi an other protists)
    (Termed Protozoa ‘first animals’, none have cell wall)
  • mixotrophic (both photosynthesise and eat, don’t have cell wall)
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4
Q

Cilia (hair-like structures) and flagella in prokaryote vs eukaryote?

A

Prokaryote: no cilia, has a helical arrangement flagella

Eukaryote: has cilia, flagella is 9:2 fibril arrangement

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5
Q

Disadvantages of using microscope to view protist cells

(Known as total count)

A
  • uses special microscope counting slide
  • does not differentiate between live and dead bacteria (need to be killed to view to prevent movement)
  • need to be ‘fix’ motile cells before hand
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6
Q

Protists Similarities to prokaryotes

A

Have cytoplasmic reticulum and ribosomes (70s vs 80s)

Both carry out asexual reproduction (binary fission vs mitosis) (bacteria = fully identical, protist = only genetically identical)

Same growth curve as bacteria

Cysts have same advantages as bacterial endospores

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7
Q

Advantages of protist cysts

A

Produced under unfavourable conditions
Highly resistant to heat, drying and radiation
Very low water constant
Some can survive for 20 years in the environment
Good resistance to antibiotics/disinfectants
Effective dispersal mechanism (can be transmitted to others via faeces)

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8
Q

Differences to bacteria

A

Different organelles eg Golgi, nucleus, cytoskeleton, etc

Only some protists have cell walls, others don’t. Those that don’t have contractile vacuoles

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9
Q

Cell walls present in which protists

A

Non-motile photosynthetic protists
All cysts have cell walls

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10
Q

Cell walls not present in which protists

A

Motile photosynthetic protists
Heterotrophic protists
Mixotrophic protists

(These overcome osmosis as water gets into their cell due to a concentration gradient using contractile vacuole)

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11
Q

How does contractile vacuole function

A

Full vacuole
Pore opens and vacuole contracts
Contraction of vacuole expels water from cell
Empty vacuole
Canal take up water from cytoplasm
Water moves from canal to vacuole

(Cycle repeats)

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12
Q

If protist in a isotonic environment, does osmosis occur?

A

No because isotonic = internal and external water content is equal. For example marine protozoa, pathogens living in sea water

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13
Q

2 types of protists, dependent on oxygen for growth

A

Obligate aerobes (need oxygen)
Obligate anaerobes (cannot grow in oxygen)

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14
Q

Endosymbiont theory

A

For mito and plastids:
- bacteria origional my living as endosymbiont in cells
- dependency then became permanent

(Alpha-proteobacterium became mitochondrion (hydrogenosome evolved from mito)
(Cyanobacterium became a chloroplast)

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15
Q

Evidence for endosymbiont theory

A

Size of organelle = size of bacterium

Phylogeny analysis relates their DNA to their bacterial origin

(Some) Have own circular DNA and replicate by binary fission

(Some) Contain same ribosomes as bacteria [70s]

Have double membrane (engulfing mechanism)

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16
Q

Selective digestion or no digestion of bacterium’s in protists leads to

A

Mixotrophy

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17
Q

Organellar mixotrophy

(Selective digestion)

A

Eats algal cells
Doesn’t digest plastids (kleptoplastids)
Plastids fix CO2
Plastids do not encode for polymerases
Die and need replenishing (so eats more)

Protists can live without the plastids

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18
Q

Cellular mixotrophy

(No digestion)

A

Eats algal cells
No digestion of algae
Algae fix CO2
Algae divide in cell
Endosymbiosis

Protist can live without the algae

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19
Q

Constitutive mixotrophs

(Algae evolve into organelles)

A

Overtime and through complicated genetic transfer events, endosynbiotic algae become true organelles

The protist cannot live without them
Only seen in flagellates

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20
Q

Different features of movement for searching and capturing prey/light in protists

A

Flagellates (flagellum/flagella)
Ciliates (cilium/cilia)
Amoebae (cytoplasmic streaming)

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21
Q

Ciliates structure

A
  • covered in cilia (tiny hair-like structures)
  • most developed protozoan
  • cytostome (mouth)
  • cytoproct (anus)
  • two types of nucleus: macronucleus and micronuclei
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22
Q

Ciliates cells structure

A

Cilia
Contractile vacuole
Micro/macronuclei
Food vacuole
Cytostome
Membranelles (stiffer cilia)
Cytoproct

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23
Q

Are cilia randomly positioned on cell surface of ciliates

A

No, they’re in distinct, strict lines and order as they need to coordinate and move as the same time to propel the cell forward / backward

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24
Q

Motile cilia

A

9+2, dynein motor protein
Ciliates
Can be found in humans (bronchial and oviduct epithelium)

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25
Q

Non-motile cilium

A

9+0, no dynein motor protein
‘Primary cilium’ on all human cells

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26
Q

What are cilia used for,

A

Movement
(Back/forward)
(Some fuse to form cirri)

Feeding
(Direct prey to cytostome)
(Cytostome contain membranelles)
(Sieve - correct sized prey enter food vacuoles)
(Filter feeding)

27
Q

Suctorian ciliates

A

Numerous microtubule tentacles
Each tentacle ends with a cytostome
Extrusomes - secrete toxins
Dissolve prey contents and suck out
‘Raptorial feeding’

28
Q

Mixotrophic ciliates

A

Do not contain their own plastids
Acquire photoautotrophic ability
Organellar mixotrophy and cellular mixotrophy

29
Q

Ciliate reproduction

A

Asexual:
Transverse ‘binary fission’
Involved mitosis

Sexual:
Conjugation
Involves meiosis and mitosis
Haploid Micronuclei swap
Allows for genetic variation

30
Q

What are lorica

A

Shells /homes that the protist builds to hide in if a predator is nearby

31
Q

Sulphur ciliates are also known as

A

Anaerobic ciliates

They produce methane by converting H2 and CO2, if not as much as needed they make it from acetate

32
Q

Flagellates

A

Posses flagellum (9+2)
- not backward and forwards movement
- in humans (sperm)

Posses macronucleus only (no micronuclei so asexually reproduce)
- longitudinal binary fission
- mainly aerobic

Feed by heterotrophy, photoautotrophy and mixotrophy

33
Q

Heterotrophic flagellates

A

Aka zooflagellates
Most are aerobic
Consume pre-formed organic carbon (prey digestion)
Use flagella for movement and catching prey: raptorial feeding, filter feeding

34
Q

Raptorial feeding with hispid flagellum

A

Create feeding currents due to flagellar movement
Prey is drawn towards the base of the flagellum
Ingested via cytoplasmic extensions (pseudopodia)

35
Q

Raptorial feeding with naked flagellum

A

Create feeding currents due to flagellar movement
Less contact with base of flagellum
Less efficient capture of prey

36
Q

Increasing prey capture with naked flagellum

A

Filter feeding

37
Q

Choanoflagellates

For example: Monosiga sp

A

Only group with a collar of tentacles
All have single naked flagellum
Attach to surface (by means of stalk)
More closely related to animals than other protists

Silica lorica in marine chaonoflagellates only

38
Q

Photoautotrophic flagellates

A

Aka phytoflagellates
Own plastids - green or golden
Photosynthesise
All are aerobic
Use flagella for movement towards light and nutrients

39
Q

Which flagellate has a 2nd flagellum around its waist

A

Dinoflagellates

40
Q

Which flagellate has a 2nd flagellum around its waist

A

Dinoflagellates

41
Q

Example of flagellates that form colonies

A

Synura

They form colonies and have golden to brown plastids.
They are also mixotrophic flagellates

42
Q

Key features of Amoebae

A

Very simple protists (single celled)
One macronucleus
Most aerobic
Most heterotrophic (some mixotrophic)
Asexual reproduction only (no specific fission plain)
Some move, some stationary
Most publicised protozoan

43
Q

Naked Amoebae features

A

Movement of cytoplasm in direction elongates cell, makes extension for movement (pseudopodia - can also be used to catch prey they feed on)

No specific location for digestion, they can digest food anywhere (use Raptorial feeding)

44
Q

Three cell forms of Naked amoebae

A

Trophizoites - feeding form

Cysts - all produce a resting stage

Floating form - stiffened pseudopodia for dispersal (stressed state, cannot feed like this, reverts to different form)

45
Q

Shelled amoebae

A

Enclosed in a test (shell)
Test can be made of anything
Intrashellular cytoplasm within test
Project extracellular cytoplasm to move and/or feed
Feeds raptorial or diffusion
Can produce cysts

46
Q

Testator amoebae

A

Freshwater,
Marine and Terrestrial
Raptorial feeding

Protrude cytoplasm outside of test do can move and bring shell with them,
Pseudopodia can also be used to eat prey

47
Q

Foraminiferans amoebae

A

Marine only amoebae
Stationary - don’t move so catch prey by protruding cytoplasm in axopodia that are sticky, Inc SA for capture of prey
Make their shells out of CaCO3 (so can become fossilised)
Feed by diffusion

48
Q

Radiolarians vs Heliozoans (Amoebae)

A

Radiolarians:
Marine only
Silica tests
Diffusion feeding

Heliozoans:
Freshwater
Silica tests
Diffusion feeding

49
Q

Amoebae ecological impact (positive)

A

“Microbial loop”

Predation stops bacteria reaching ‘stationary phase’

Heterotrophic protozoa act as farmers and take care of their prey (release carbon when respite and simultaneously pump out PO2 and NH4 to maintain cellular C:N:P ratio

50
Q

Amoebae ecological impact (negative)

A

Bacteria can develop into pathogenic bacteria by practicing on amoebae

(Change their antigens so can’t be recognised by receptors - macrophages are nearly identical)
(Stop fusion of lysosomes with phagosome so not digested, they divide or escape phagosome and grow inside cell - increasing numbers)

Amoebae act as a reservoirs for pathogenic bacteria - transported to host via air or water

51
Q

Medical impacts of protists; humans

A

90% of human cells are bacteria

One protist naturally present

One amoebae in us: Entamoeba coli

Exist in the gut - not pathogenic

Fit is site of most bacteria

52
Q

Medical impacts of protists; infections caused - humans

A

Gut infections eg Dysentery

Eye infections eg Keratitis

Brain infection eg Naegleria fowleri causes Primary Amoebic Meningoencephalitis (PAM)

STDs eg Trichomonad vaginalis causes Trichomoniasis

Blood/Tissue infection eg Leishmania mexicana causes Leishmaniasis

53
Q

What is the microbial loop

(Impact on ecological - protists)

A

Photoautotrophs make more sugar than need so leak sugar out of cells.

Bacteria feed off the waste / sugar from the photoautotrophs

Bacteria are infested by heterotrophic Protozoa (act as farmers and take care of their prey by releasing C when respire and pump out PO2 and NH4)

Heterotrophic Protozoa are ingested by photoautotrophs and metazoan

54
Q

Raptorial feeding?

A

Prey is engulfed and digested

55
Q

Diffusion feeding

A

Prey gets stuck to cytoplasm and sucked into the cell

56
Q

LEARN EXAMPLES FOR DISEASE CAUSED BY PROTIST

(Located on Lecture 6 - BIOL 121)

A

Name the protist
It’s reservoir
Mode of transmission

57
Q

The fossils of which group of amoeba are abundant in the White Cliffs of Dover

A

Foraminifera

58
Q

The fossils of which group of amoeba are abundant in the White Cliffs of Dover

A

Foraminifera

59
Q

What am I?
I am a small protist (5-10um in length) with a single flagellum. I attach myself to surfaces by means of a stalk. I trap bacteria in my many tentacles, which form a collar at the base of my flagellum. Some believe I am the ancestor of all animals

A

Monosiga so.

60
Q

Eye infection caused by protists example

A

Amoebae genus Acanthamorba
Causes Keratitis
Reservoir = water
Transport: dirty contact lenses
Treatable but can lead to glaucoma

61
Q

Brain infection caused by protist example

A

One amoebae: Naegleria fowleri
Causes Primary Amoebic Meningoencephalitis (PAM)
Reservoir: Warm water
Transmission: Flagellate swims up nose
No treatment: fatal

62
Q

Sexually transmitted disease caused by protist example

A

One flagellate: Trichomonas vagunalis
Causes Trichomoniasis
Aerobic and no cysts
Infects urethra, vagina, prostate
Reservoir: humans (males asymptomatic)
Transmission: sexual inter course
Treatable

63
Q

Blood /tissue infections caused by protists example

A

Flagellates: Leishmania mexicana
Causes Leishmaniasis
Aerobic, no cysts
Reservoir: dogs
Transmission: sand fly (vector)
‘Visceral’ - attacks tissues eg spleen and liver
‘Cutaneous’ - infects macrophages and divides within
Treatable

BIOL 121 - Impact Of Microbes (4 decks)

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