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BIO 121 > Key stuff - Protists and Amoebae > Flashcards

Key stuff - Protists and Amoebae Flashcards

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Biology 101 flashcards
1
Q

What are protists

A

eukaryotes

majority are single celled

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2
Q

Cytoskeleton

A

for trafficking organelles

allow movement of organelles to correct ares, specific areas.

(tubular, actin, throughout cytoplasm)

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3
Q

Photoautotrophic protists

A

contain plastids (green, red or golden)

green plastid = chloroplast

photosynthesis

Termed ‘Algae’ (some have a cell wall)

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4
Q

Heterotrophic protists

A

feed on bacteria, fungi and other protists

termed ‘Protozoa’ (‘first animals’) (none have a cell wall)

Bacteria is ‘favourite’ prey.

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5
Q

Mixotrophic bacteria

A

Feed on bacteria, fungi and other protists and photosynthesise (none have a cell wall)

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6
Q

Direct microscopic count.

A

easy and fast

Uses special microscope counting slide

-does not differentiate between live and dead bacteria

motile protists have to be killed as easier to count.

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7
Q

Same population growth curve. as bacteria:

A

Lag phase- Time interval between inoculation and maximal division rate: cells adjust to new environment.

Log phase- constant doubling time, growth rate is maximal

stationary phase- can no longer reproduce but are still alive (e.g no food left)

death (decline) phase- death or cyst formation.

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8
Q

Cysts

A

Produced under unfavourable conditions

highly resistant to heat, drying and radiation.

very low water content

can survive for 20 years I the environment

good resistance to antibiotics/disinfectants

effective dispersal mechanism (can be transmitted to others via faeces)

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9
Q

Cell walls of protists

A

Always present in:
non-motile photosynthetic protists
cysts (even if protist that produced them does not have a cell wall)

Not present in:
motile photosynthetic protists
heterotrophic protists
mixotrophic protists

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10
Q

Temperature cut off

A

60

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11
Q

Oxygen and protist growth

A

Obligate aerobes

Obligate anaerobes

‘jury’ is out to whether we have microaerophillic eukaryotes (current investigation)

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12
Q

Respiration

A

Aerobic - mitochondria

anaerobic- hydrogenosomes
(pyruvate to H2, acetate, co2)

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13
Q

What became a mitochondrion after endosymbiosis?

A

alpha-proteobacterium

hydrogenosome evolved from mitochondria

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14
Q

What became chloroplasts after endosymbiosis

A

cyanobacterium

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15
Q

Food vacuole (phagosome) dynamics in protists

A

only certain part of membrane used for feeding.

bacterium to receptors, then phagocytosis stuff, membrane recycling

soluble and insoluble debris released by exocytosis.

if food escapes, it will take membrane of phagosome. will have 2 membranes.

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16
Q

Organellar mixotrophy

A

-eats algal cells

-does not digest plastids (kleptoplastids)

-plastids fix co2

-plastids do not encode for polymerases

-die and need replenishing (so eats more)

-protist can live without the plastids

-ciliates and amoebae

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17
Q

cellular mixotrophy

A

-eats algal cells

-no digestion oof algae

-algae fix co2

-algae divide in cell

-protist can live without the algae

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18
Q

constitutive mixotrophs

A

over time and through complicated genetic transfer events

endosymbiotic algae become true organelles

only seen in flagellates

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19
Q

Ciliates

A

covered in cilia

most developed protozoan

cytosine (mouth)

cytoproct (anus)

Two types of nucleus:
-macronucleus
-micronuclei

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20
Q

Cilia

A

Microtuble-based hair-like organelles

used for movement
-go back and forward
-some fuse to form ‘cirri’

very important for feeding
-direct prey towards the mouth are (‘cytostome’
-cytostome contains stiffer cilia (‘membranelles’)
-sieve- correct sized prey enter food vacuoles
-‘filter feeding’

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21
Q

Motile cilia

A

9+2, dyne motor protein

ciliates

humans (bronchial and oviduct epithelium)

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22
Q

non-motile cilium

A

9+0, no dyne motor protein

‘primary cilium’ on all human cells.

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23
Q

prey drawn towards cell

vortex at cell mouth

very large feeding currents

‘Mexican wave’ by cilia on top forms vortex of water which draws prey towards oral area. Scared and easily contracts on impact.

A

vorticella

24
Q

Suctarian ciliates

A

numerous microtubule tentacles

each tentacle ends with a cytostome

extrusomes - secrete toxins

dissolve prey contents and suck out.

‘raptorial feeding’

25
Q

mixotrophic ciliates

A

do not acquire their own plastids

acquire photoautotrophic ability two ways

organelle mixotrophy and cellular mixotrophy.

26
Q

Macronuclues

A

Controls the cell.

27
Q

Micronucleus

A

only used for sexual reproduction

28
Q

Ciliate reproduction

A

Asexual reproduction:
-transverse ‘binary fission’
-involves mitosis

Sexual reproduction
-conjugation
-involves meiosis and mitosis
-micronuclei swap
-allows for genetic variation.

29
Q

Flagellates

A

possesses flagellum/flagella (9+2)
-not backwards and forwards
-in humans- sperm

possesses macronucleus only
-longitudinal ‘binary fission’

mainly aerobic

feed by heterotrophy, photoautotrophy and mixotrophy.

30
Q

Heterotrophic flagellates

A

also called ‘zoo flagellates’

most are aerobic

consume pre-formed organic carbon

prey digestion
-organic carbon to inorganic carbon (mineralisation)

use flagella for movement and catching prey
-raptorial feeding
-filter feeding

31
Q

Naked flagellum

A

forward swimming

32
Q

Hipsid flagellum

A

backwards swimming

33
Q

Raptorial feeding (with hips flagellum)

A

create feeding currents due to flagellar movement

prey is drawn towards the base of the flagellum

ingested via cytoplasmic extension (pseudopodia)

more efficient , base of flagella only place of ingestion.

34
Q

Raptorial feeding (with naked flagellum)

A

create feeding currents due to flagellar movement

less contact with the base of the flagellum

less efficient capture of prey

35
Q

Increasing prey capture (with a naked flagellum)

A

extensions to cell.

catches prey at base of flagellum

covered in scales(drawing pins)

pierce prey and move around surface of cell.

collar of tentacles (microvilli)

contain actin - contractile

36
Q

Choanoflagellates

A

only group with a collar of tentacles

all have a single naked flagellum

attach to surface (by means of a stalk)

more closely related to animals than other protists.

37
Q

silica lorica made only in choanoflagellates, how are they made.

A

Mother cell makes loads of little glass strips.

Glues together in right places. Bundle produced.

Goes on to divide and daughter cell is pushed into two bundles and then released.

Collar of tentacles grabs top of the bundle, then turns round one and a half 2 times and then tentacles pull everything up.

Bundle now expands and becomes fully built lorica.

38
Q

biomimetic engineering

A

due to twist of lorica. gives enhanced strength and rigidity.

39
Q

photoautotrophic flagellates

A

also called ‘phytoflagellates’

own plastids - green or golden

all are aerobic

use flagella for movement towards light and nutrients.

40
Q

Euglena (photoreception)

A

eyespot/stigma:
organelle containing carotenoid lipid globules. Shading device for photoreceptor to detect direction of light.

41
Q

Dinoflagellates

A

contain a second flagellum around the waist.

42
Q

Amoebae

A

One macronucleus

most are aerobic

most are heterotrophic
-some mixotrophic

asexual reproduction only
-no specific fission plane (can divide across any part of their membrane, not controlled.

some move, some are stationary

most publicised protozoan.

43
Q

Naked amoebae

A

move by cytoplasmic streaming

produce pseudopodia on surface

pseudo phobia used to creep across surfaces

feed by direct interception of prey

raptorial feeding

no specific location of ingestion - can be anywhere.

44
Q

Naked amoebae - 3 cell forms

A

Trophozoites - the feeding form

cysts- all produce a resting stage

floating form- stiffened pseudopodia for dispersal

all amoeba produce cysts.

45
Q

Shelled amoebae

A

enclosed in shell (‘test’)

shell can be made of anything

intrashellular cytoplasm within test

project extrashellular cytoplasm to move and/ or feed.

raptorial or diffusion feeding

can produce cysts.

46
Q

Testate amoebae

A

freshwater, marine and terrestrial

raptorial feeding

made shells out of spent algae

47
Q

Foraminiferans

A

marine only CaCO3 tests

diffusion feeding

48
Q

diffusion feeding

A

stationary predator captures prey with sticky extrashellular cytoplasm (‘axopodia’)

49
Q

Radiolarians

A

marine only

silica tests

diffusion feeding

50
Q

heliozoans

A

freshwater

silica tests

diffusion feeding

51
Q

Good ecological impact of protists

A

The microbial loop.

predation keeps bacteria in ‘log phase’

52
Q

Protists cellular C:N:P ratio

A

50:10:1

has to be maintained at this, excess released.

53
Q

Bad ecological impact

A

evolution of pathogens

evident in amoebae as share many similarities with macrophages

bacteria practice evading digestion in amoebae

become pathogenic and evade our immune system.

54
Q

Evading digestion in amoebae

A

either change antigens so not recognised by receptors.

be covered in a thick capsule so not detected, receptors cannot bind

or can release chemicals which prevent the digestive enzymes fusing with the phagosome.

55
Q

How much of human cells are bacterial

A

90%

one protist naturally present

56
Q

Visceral

A

attacks tissues

57
Q

Cutaneous

A

infects macrophages and divides within

BIO 121 (7 decks)

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