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Michaelmas Term 1 > Eukaryotic Microbes – Innovations in Biology > Flashcards

Eukaryotic Microbes – Innovations in Biology Flashcards

1
Q

Protista were divided into:

A
  • Monera (bacteria and blue-
    green algae without a nuclear
    membrane).
  • Eunucleata (unicellular
    organisms with a nuclear membrane).
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2
Q

Evolutionary relationships are reconstructed from

A

study of reliable homologous characteristics.

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3
Q

Describe phylogenetic resolution across time

A

100 homologous characteristics in 1980’s, now >1000.

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4
Q

Describe the eukaryote cell structure

A
  • typically much larger and more complex than prokaryote cells.
  • membrane enclosed nucleus
  • mitochondria
  • hydrogenosomes and a strictly fermentative metabolism or mitosomes
  • nucleus contains linear chromosomes
  • DNA is wound around histones: Chromatin.
  • chloroplasts present in phototrophic cells
  • cell wall present in fungi, algae, plants and some protists
  • some have cilia or flagella for movement
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5
Q

Describe some eukaryotes with hydrogenosomes and a strictly fermentative metabolism

A
  • Trichomonas
  • some fungi
  • ciliates living in the rumen and animals
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6
Q

Who has mitosomes?

A

Giardia

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7
Q

histones

A

positively charged proteins

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8
Q

What are the six eukaryotic supergroups

A
  • Archaeplastida
  • Rhizaria
  • Chromoalveolata
  • Excavata
  • Amoebozoa
  • Opisthokonta
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9
Q

SAR phylogenetic cluster

A
  • Stramenopiles
  • Alveolata
  • Rhizaria
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10
Q

Archaeplastida

A

Plants, red and green algae

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11
Q

Rhizaria

A

Mostly heterotrophic unicellular organisms

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12
Q

Chromoalveolata

A

Stramenopiles: unicellular flagellates and diatoms
Alveolata: widespread group predators and parasites (e.g. Paramecium)

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13
Q

Excavata

A
  • Mostly heterotrophs
  • includes pathogens
  • many anaerobic
  • e.g. Giardia, Trypanosoma
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14
Q

Amoebozoa

A

Many forms of amoeba including Dictyostelium, slime moulds.

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15
Q

Opisthokonta

A

Fungi, Animalia

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16
Q

Define protists

A

single-celled or very few celled eukaryotes that are not plants, animals or fungi.

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17
Q

Define protoctists

A
  • single-celled and multicellular eukaryotes that do not fit into the other kingdoms
  • largely historical term
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18
Q

Define protozoans

A

nformal term referring to unicellular, primarily “heterotrophic” eukaryotic organisms (“animals”)

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19
Q

Describe protist distribution and diversity

A
  • between 1.4x10^5 and 1.6x10^6 species
  • occupy every conceivable ecological niche
  • parasitic forms challenge a wide range of hosts
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20
Q

Foraminiferans

A

calcium carbonate ‘tests’

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21
Q

Chlamydomonas

A

Unicellular green algae

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22
Q

Trypanosoma brucei

A

parasitic

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23
Q

List some niches occupied by protists

A
  • marine trenches
  • rainforests
  • artesian and thermal springs
  • salt lakes
  • ice flows; glaciers
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24
Q

Dinoflagellates

A

‘red tide’

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25
Q

Plasmodium

A

parasitic

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26
Q

Describe the variable size of protists

A
  • ## 5-500micrometres
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27
Q

Cryptosporidium

A
  • Apicomplexan
  • c. 5micrometres
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28
Q

Giardia

A
  • Diplomonad
  • c. 10micrometres
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29
Q

Trichonympha

A
  • Parabasalid
  • c. 100micrometres
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30
Q

Amoeba

A

150-400 μm

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31
Q

Describe protist nutrition

A
  • aerobic and respire
  • photosynthetic
  • heterotrophic
  • predatory
  • parasitic
  • intracellular and extracellular niches
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32
Q

Describe aerobic protists

A
  • mitochondria
  • mitosome
  • hydrogenosomes
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33
Q

Describe heterotrophic protists

A

absorb extracellularly-digested food

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34
Q

Discuss a predatory protist

A

amoeba and some ciliates, such as Paramecium.

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35
Q

Why are protists underrepresented?

A
  • bias towards species that are phototrophic, parasitic or economically important
  • Archaeplastida and Stramenopila easier to culture
  • pathogens Toxoplasma and Plasmodium within Alveolata/Apicomplexans
36
Q

Describe Pneumocystis

A
  • opportunistic pathogen causing pneumonia in immunocompromised patients.
  • fungus
  • treated with antifungal agents
37
Q

Describe Phytophthora

A
  • cause of potato blight
  • Stramenopiles
38
Q

Describe the Holozoa

A
  • most closely related unicellular lineages to animals
  • Choanoflagellatea closest
  • Filasterea and Ichtyosporea also closely related
39
Q

Describe the first animals

A

evolved from an unknown ancestor in the pre-Cambrian period.

40
Q

In order to learn how animals evolved,

A

phylogenetic relationships are reconstructed from extant organisms.

41
Q

Describe the multiple origins of multicellularity

A

16-22 times

42
Q

Describe multicellularity in the tree of life

A

Metazoa and Embryophyta contain only multicellular organisms

43
Q

Describe adhesion

A
  • plants use pectin and hemicellulose
  • fungi use extracellular glycoproteins
  • animals use cadherins and integrins
44
Q

Describe Pseudopodia

A
  • temporary projections of the plasma membrane.
  • extend and contract by the reversible assembly of actin subunits into microfilaments.
  • Rhizaria have more threadlike pseudopodia than Amoebae.
  • used for phagocytosis
45
Q

phagocytosis

A

sensing and engulfing targets for ingestion.

46
Q

Describe flagella

A
  • rapid ‘whip like’ motion
  • crucial for survival, cell feeding and reproduction
  • ‘9+2’ microtubule axoneme.
  • organelles associated with their own metabolism
  • respond to and initiate signal- transduction cascades
47
Q

Describe cilia

A
  • hair-like structures,
  • large numbers on the cell surface
  • 0.25 microns in diameter
  • 2-20 microns long.
  • alternating power and recovery strokes
  • ‘wave’ like motion
  • generate force perpendicular to the cilia’s axis
  • synchronised beats (coordinated by hydrodynamic linkage)
  • generally faster
48
Q

Describe binary fission

A

Division into two approximately equal parts where cytoplasmic division follows mitosis

49
Q

Describe flagellate binary fission

A

longitudinal plane

50
Q

Describe Amoeba division

A
  • no fixed plane of division
  • round up and divide into two basically equal halves
51
Q

Describe ciliate binary fission

A
  • equatorial or transverse plane
  • maintain the correct number of cilia
  • replication of the cytostome precedes the division of the cytoplasm
52
Q

Describe endodyogeny

A
  • each DNA replication cycle is followed by mitosis and budding
  • e.g. T. gondii
53
Q

Describe leukocyte transformation

A
  • sporozoites infect leukocytes
  • transforms them and divides by exploiting the mitotic and cytokinetic machinery of the host
  • Theileria spp.
54
Q

Describe Schizogony

A
  • nuclei multiply by asynchronous rounds of mitosis
  • last round is synchronous for all nuclei and coincides with budding at the parasite surface
  • e.g. P. falciparum, Eimeria
55
Q

Describe Endopolygeny

A
  • DNA replicates without nuclear division, using multiple synchronous mitotic spindles
  • final mitotic cycle coincides with budding and the emergence of a new generation of merozoites
  • T. gondii in cats
56
Q

Describe ciliate sexual reproduction

A

compatible mating types exchange genetic material

57
Q

Describe ciliate conjugation

A
  • two cells contact
  • cytoplasmic bridge forms
  • micronuclei undergo meiosis: four micronuclei per cell
  • three micronuclei disintegrate; one mitoses
  • micronuclei exchange
  • cells separate, micronuclei fuse, micronuclei disintegrate
  • new macronucleus forms in each cell from mitotic divisions in micronucleus
58
Q

Describe gametogony and sporogony in Eimeria (Apicomplexa) spp.

A
  • sporulated oocyst ingested
  • sporozoites escape from the
    sporocyst and invade epithelial cell
  • sporozoites under shizogony
  • merozoites leave cell and infect another cell
  • shizogony repeated until the final merozoites form into macrogametocytes and microgametocytes
  • after fertilisation, oocyst is formed
  • passes to the environment and undergoes meiosis and mitosis to form sporocysts containing sporozoites
59
Q

Describe Eimeria

A
  • > 1,000 described species
  • infect fish, birds, reptiles and mammals
  • important veterinary pathogen
60
Q

schizogony basics

A

asexual multiple fission

61
Q

Describe Excavata, Euglena gracilis

A
  • free-living aquatic unicellular protist
  • model organism
  • photoautotrophic
  • heterotrophic
  • mixotropic
  • swim using flagella
  • creep using metaboly
  • covered by a pellicle
  • natural tolerance to acidic growth conditions and ionizing radiation
  • sequesters heavy metals
  • uniquely reserve the carbohydrate Paramylon for use as a Carbon source under Carbon starvation conditions
62
Q

metaboly

A

a peculiar type of “inching” locomotion

63
Q

pellicle

A
  • flexible coat
  • allows the cell to change shape
64
Q

Describe the bioproducts from Euglena gracilis

A
  • nutrition
  • nutraceuticals and biomedicine
  • biofuels and biomaterials
  • large-scale cultivation
65
Q

Describe E. gracilis nutrition

A
  • dietary protein
  • (pro)vitamin A, C, E
  • polyunsaturated fatty acids
  • dietary fibre
66
Q

Describe E. gracilis nutraceuticals and biomedicine

A
  • beta-1,3-glucan paramylon
  • paramylon derivatives
67
Q

Describe E. gracilis biofuels and biomaterials

A
  • lipids (wax esters)
  • fermentable sugars
  • biogas and bio-oil
  • bioplastics and nanofibres
68
Q

Describe large-scale cultivation by E. gracilis

A
  • outdoor cultivation
  • (photo)bioreactors
69
Q

Describe Alveolata, Paramecium

A
  • unicellular ciliate
  • model organism
  • widespread in freshwater, brackish water and marine environments
  • most are heterotrophs feeding on bacteria
  • some are mixotrophs, using nutrients from chlorella in the cell cytoplasm
  • cilia used for motility and to move food along a groove towards the cell mouth
  • food phagocytosed and enclosed in the vacuole, where it is broken down by enzymes
  • reproduce asexually by binary fission
  • conjugation can be induced by food shortage
70
Q

chlorella

A

endosymbiotic algae

71
Q

List some protist diseases

A
  • Malaria
  • Leishmaniosis
  • Cryptosporidiosis
  • Amoebiasis
  • Chagas disease
  • African Trypanosomiasis
  • Schistosomiasis
72
Q

Describe Giardiasis

A
  • Giardia intestinalis (Excavata)
  • two nuclei of equal size
  • flagellated
  • heterotrophic (low oxygen environments)
  • no mitochondria; mitosomes
  • asymptomatic to severe diarrhoea and malabsorption
73
Q

Describe the symptoms of Giardiasis

A
  • diarrhoea
  • abdominal pain
  • bloating
  • nausea, and vomiting
74
Q

Describe Entamoeba (Amoebozoa)

A
  • parasites of vertebrates and invertebrates
  • several species infect humans
  • anaerobic (mitosomes)
  • cysts in free-living dispersal stage
75
Q

List some free-living Amoebozoans

A

Gymnamoebas & slime molds

76
Q

Describe Amoebozoans

A

free-living (fresh water, soil)

77
Q

Describe Entamoeba gingivalis

A

oral cavity

78
Q

Describe Entamoeba coli

A

intestinal tract

79
Q

Describe Entamoeba histolytica

A
  • trophozoite causes dysentery, ulceration, bloody diarrhoea, liver abscess
  • readily killed in the environment
80
Q

Describe Entamoeba cysts

A

excreted in the host’s faeces and survive in water or the soil

81
Q

Eimeria spp. on livestock

A
  • infect almost all vertebrates
  • particularly young
  • farmed animals (esp. poultry)
82
Q

Describe Cryptosporidium spp.

A

wide impact on young animals

83
Q

Describe Toxoplasma gondii

A
  • infection of cats
  • can cause severe disease in other animals (incl. foetal
    damage)
84
Q

Describe Giardia intestinalis

A

persistent problem for many animals

85
Q

Describe Leishmania spp.

A
  • zoonosis with a reservoir of infection in dogs
  • transmission to dogs by infected sandfly
86
Q

Describe Trypanosoma brucei

A
  • cattle
  • transmitted by Tsetse fly in areas of Africa

Michaelmas Term 1 (42 decks)

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