Lecture 11: Taxonomy of Eukaryotes

Question 1

How do you determine phylogeny for eukaryotes?

Answer 1

MLST&18s genes sequencing

Question 2

True or False. The relationship between 18s rRNA genes is weaker for eukaryotes than 16s RNA for prokaryotes.

Answer 2

True

Question 3

Primary endosymbiosis refers to what?

Answer 3

Cell engulfs bacteria->become mitochondrion/chloroplast

Cell form cyanobacteria lineage of bacteria engulfed too

Question 4

Secondary endosymbiosis refers to what?

Answer 4

Cyanobacterial cells diverge to separate lineages
Red algae-> turns into chloroplast (Dinoflagellates/Apicomplexans)
Green algae->turns into chloroplast
(Euglenids/chlorarachniophytes)

Question 5

What are green algae? (Chlorophytes)

Answer 5

• Closely related to plants, mostly inhabit freshwater
• can be unicellular or multicellular
• can reproduce sexually/asexually
• endolithic algae grow inside porous rocks

Question 6

What are red algae? (Rhodophytes)

Answer 6

• Mostly marine, some freshwater/terrestrial
• Mostly multicellular, can be unicellular
• Unicellular->Galdieria

Question 7

What gives red algae their colour?

Answer 7

Phycoerythrin->accessory pigment

More created by cells @ greater depth

Question 8

Describe the role of red and green algae in secondary endosymbiosis.

Answer 8

Are the precursors of chloroplasts

Question 9

What is a diplomonad? (Girardia)

Answer 9

Eukaryote with 2 nuclei of equal size
Have mitosomes
Lacks ETC and TCA enzymes

Question 10

What is a parabasalid? (trichomonas)

Answer 10

Eukaryote without mitochondria
Have hydrogenosomes (anaerobic metabolism)
contain parabasal body (supports golgi)

Question 11

What do diplomonad and parabasalids have in common?

Answer 11

Both unicellular eukaryotes, flagellated, no chloroplasts, live in anoxic environments

Question 12

What are amitochondriate eukaryotes?

Answer 12

Eukaryotes without mitochondria. Contain mitosomes of hydrogenosomes instead.

Question 13

What is a mitosome?

Answer 13

Derived from mitochondria, reduced form
No TCA enzymes/ respiratory chain
Involved in maturation of FeS clusters

Question 14

What is a Hydrogenosome?

Answer 14

Present in eukaryotes whose metabolism is strictly fermentative
Oxidizes pyruvate to H2, Co2 and acetate
Sometimes H2 consuming archaea also present (Methanogens)->primary endosymbiosis

Question 15

What is a cyst?

Answer 15

Specialized structure, more protists differentiate into cysts (encysted)
Protect cells from environment
Survive long periods of starvation/dessication
Survive infection by prokaryotes

Question 16

How does Girardia lamblia cause Giardiasis? (Diplomonad)

Answer 16

1. Food/water is contaminated
2. Cysts go to trophozoite form in intestine, multiply and go back to cyst form
3. Cysts and trophozoites passed in stool, only cysts survive

Question 17

How does trichomonas Vaginalis cause an STI? (Parabasalid)

Answer 17

• Doesn’t survive well outside (doesn’t form cysts)

- Transported through body fluids

Question 18

What are euglenozoans?

Answer 18

Unicellular flagellated eukaryotes

Question 19

What is a kinetoplastid? (Euglenozoan)

Answer 19

• Contain kinetoplast (mass of DNA in single mitochondrion)

- Live in aquatic environments, feed on bact.

Question 20

What does Trypansoma brucei cause? (Kinetoplastid)

Answer 20

African sleeping sickness (carried by tsetse fly)

Question 21

What is a Euglenid?

Answer 21

• Flagellate, non pathogenic and phototrophic
• contains chloroplasts
• can also feed on bact., lose chloroplast if lives in the dark

Question 22

What is an aveloate?

Answer 22

• Protist, contain alveoli (sacs under cytoplasmic membrane)
• May function to help cells maintain osmotic balance
• contractile vesicle in paramecium

Question 23

What is a ciliate?

Answer 23

• Posses cilia at some stage of their life
• Use cilia for motility and to obtain food
• have two nuclei (macro and micronuclei)

Question 24

What are Dinoflagellates?

Answer 24

Marine/freshwater phototrophic organisms

Question 25

What are apicomplexans?

Answer 25

Obligate parasites of animals Complex life cycle 1. Sporozoite-> cell that infects new hosts 2. Gametocyte-> gamete forming cells Contain apicoplasts Can cause malaria (Plasmodium falciparum)

Question 26

What is an apicoplast?

Answer 26

Degenerated chloroplasts | Lack pigments and phototrophic activity, but still carry many anabolic pathways

Question 27

What is a stramenophile?

Answer 27

Chemoheterotrophs Have flagella with many short hairlike extensions Includes oomycetes, diatoms, golden algae, brown algae

Question 28

What are oomycetes? (stramenophile)

Answer 28

Also called H2O molds Filamentous growth, presence of coenocytic (multinucleate) hyphae=no cell division Cell walls made of cellulose (P. infestans=potato famine)

Question 29

What is golden algae? (stramenophile)

Answer 29

Phototrophs, also called chrysophytes Mostly unicellular, some are colonial (form groups) Chloroplast pigments dominated by carotenoid fucoxanthin

Question 30

What are diatoms?

Answer 30

Unicellular/phototrophic Freshwater/marine habitats Contain fustules

Question 31

What is a fustule?

Answer 31

Cell walls made of silica, proteins, polysacchs. Protect against predation.

Question 32

What are cercozoans?

Answer 32

Exclusively marine organisms, unicellular protist Form ornate shell like structures (tests) Tests made from organic materials reinforced with calcium carbonate

Question 33

What are radiolarians?

Answer 33

Mostly marine, heterotrophic | Test made of silica

Question 34

What are some similarities between cercozoans and radiolarians?

Answer 34

Both unicellular, distinguished from other protists by pseudopodia

Question 35

What are amoebozoa?

Answer 35

Terrestrial and aquatic protists Use pseudopodia Phagocytosis of bact and smaller protists move by cytoplasmic streaming

Question 36

What are the main groups of amoebozoa?

Answer 36

Gymnamoebas, entamoebas, slime molds

Question 37

What are gymnamoebas?

Answer 37

Free living amoeba, inhabit soil and aquatic environments

Question 38

What are entamoebas?

Answer 38

Parasites of vertebrates and invertebrates

Question 39

What are plasmodial slime molds?

Answer 39

several kinds of unrelated eukaryotic organisms that can live freely as single cells, but can aggregate together

Question 40

What is the life cycle of a plasmodial slime mold?

Answer 40

Have vegetative forms-> masses of protoplasm Indefinite shape and size (plasmodium) Multiple nuclei 1. Sporangium can form, containing multiple haploid spores 2. Spores germinate=swarmer cell 3. 2 swarmer cells can join=diploid plasmodium

Question 41

What are cellular slime molds?

Answer 41

Vegetative forms compose of single amoebae (haploid) | Aggregate of multiple amoeboid cells=pseudoplasmodium (slug)-cells do not fuse

Question 42

Whats the difference between cellular and plasmodial slime molds?

Answer 42

Cellular=1 cell aggregated | Plasmodial=mass of protoplasm

Question 43

How do cellular slime molds reproduce?

Answer 43

When fruiting body formed, cells differentiate into spores | May undergo sexual reproduction to form diploid macrocysts+meiosis

Question 44

True or false. Slime molds are capable of primitive agriculture.

Answer 44

true

Question 45

True or false. Fungi are multicellular.

Answer 45

True

Question 46

True or false. Slime molds are capable of primitive agriculture.

Answer 46

True

Question 47

What are the two different kinds of hypha fungi can have?

Answer 47

Cyoenocytic | Separate

Question 48

Whats the difference between coenocytic and separate hyphae?

Answer 48

Coenocytic: Cytoplasm and nuclei not subdivided into cells Separate: Nuclei separated by cross wall

Question 49

What are fungal walls made of?

Answer 49

Chitin

Question 50

How do fungi feed?

Answer 50

Secrete extracellular enzymes that digest complex organic materials

Question 51

How do fungi create asexual spores?

Answer 51

Hyphae that extend above surface produce asexual spores (conidia)-pigmented, resistant to drying

Question 52

What is a conidiophore?

Answer 52

Specialized reproductive hyphae

Question 53

How do fungi form symbiotic association with plant roots?

Answer 53

Some species of fungi (Mycorrhizae) form close relationships with plant roots =glomeromycetes Mycorrhizae help plant roots obtain P, in turn fungi obtain nutrients from plant

Question 54

What are ectomycorrhizae?

Answer 54

Bacteria that form a sheath around plant root-doesn't penetrate fungal hyphae embedded in plant root

Question 55

How do fungi cause disease?

Answer 55

Form specialized hyphae (haustoria) to penetrate plant cells, consume cytoplasm

Question 56

What is mycoses?

Answer 56

fungal infection of animals

Question 57

How do fungi reproduce asexually?

Answer 57

1. Grow and spread hyphal filaments 2. Asexual reproduction of spores 3. Simple cell division (budding)

Question 58

How do fungi reproduce sexually?

Answer 58

Form sexual spores from fusion of two haploid cells then undergoes meiosis

Question 59

How does S. cerevisae reproduce?

Answer 59

1. Bud into haploid cells 2. Form two different sexed cells (a and alpha) which undergo cell fusion 3. Fused cell undergoes nuclear fusion and meiosis =ascus 4. Creates new haploid ascospores

Question 60

What is an ascospore?

Answer 60

Sexual fungal cells (s. cerevisae)

Question 61

What are the three different kinds of fungal spores?

Answer 61

Ascospores, basidospores, zygospores.

Question 62

What is lichen?

Answer 62

Association between fungi and algae/cyanobacteria