Taxonomy of Eukaryotes

Question 1

Endosymbiosis Theories

Answer 1

• Eukaryotes began as a nucleus-bearing lineage that later acquired mitochondria & chloroplasts by endosymbiosis
• Intracellular association between a H2-producing bacteria gave rise to mitochondria & an H2-consuming archaeal host. Nucleus was later developed

Question 2

Amitochondriate eukaryotes

Answer 2

Eukaryotes that lack a mitochondrion

Question 3

Mitosomes

Answer 3

• Reduced form of mitochondrion (no TCA or ETC)
• Involved in the maturation of iron-sulfurclusters

Question 4

Hydrogenosome

Answer 4

• Present in eukaryotes whose metabolism is strictly fermentative
• carries out the oxidation of pyruvate to H2 , CO2 and acetate

Question 5

Cysts: Functions

Answer 5

Protect the cells against deleterious environmental conditions

Question 6

Major clades of Eukaryia

Answer 6

6 major clades:
* Archaeplastida
* Rhizaria
* Chromalveolata
* Excavata
* Amoebozoa
* Opisthokonta

Question 7

Are eukaryia phylogenetically closer to bacteria or archaea?

Answer 7

Archaea

Question 8

Archaeplastida: Species

Answer 8

• Red Algae (rhodophytes)
• Green Algae (chlorophytes)

Question 9

Rhodophytes: Characteristics

Answer 9

• Mostly marine, some freshwater/terrestrial
• Red color is from phycoerythrin
• Mostly multicellular

Question 10

Chlorophytes: Characteristics

Answer 10

• Mostly freshwater, some marine/terrestrial
• Unicellular (flagellated) or multicellular
• Sexual & asexual reproduction

Question 11

Excavata: General characteristics

Answer 11

• Unicellular
• Flagellated
• Lacks chloroplasts
• Live in anoxic habitats

Question 12

Excavata: Species

Answer 12

• Diplomonads
• Parabasalids
• Kinetoplastids
• Euglenids

Question 13

Diplomonads

Answer 13

• Have 2 nuclei of equal size
• Have mitosomes
• Ex: Giardia (cause giardiasis)

Question 14

Parabasalids

Answer 14

• Contain a parabasal body
• Have hydrogenosomes
• Ex: Trichomonas (STD in humans)

Question 15

Euglenoids

Characterised by? Species?

Answer 15

• unicellular flagellated eukaryotes
• Kinetoplastids & Euglenids

Question 16

Kinetoplastids

Answer 16

• Characterised by presence of kinetoplast
• Ex: Trypanosoma

Question 17

Trypanosoma brucei (Kinetoplastid)

Disease? Environment? Transmission?

Answer 17

• Causes African sleeping sickness
• Lives and grows in the bloodstream
• Transmitted by the tsetse fly.

Question 18

Kinetoplasts

Answer 18

A mass of DNA present in
their single, large mitochondrion

Question 19

Euglenids

Answer 19

• Nonpathogenic & phototrophic.
• Contain chloroplasts, can exist as heterotrophs; will lose its chloroplast if incubated in the dark for a long time.
• Can feed on bacteria by phagocytosis

Question 20

Chromalveolata: Species

Answer 20

Alveolata:
* Ciliates
* Dinoflagellates
* Apicomplexans

Stramenophiles:
* Oomycetes
* Golden algae
* Diatoms

Question 21

What are alveolates characterised by?

Answer 21

Characterized by the presence of alveoli (sacs underneath the cytoplasmic membrane) which help cells maintain osmotic balance
* In Paramecium: alveoli = contractile vacuole

Question 22

Ciliates

Answer 22

• Cilia for motility and food
• 2 nuclei (macronucleus & micronucleus)

Question 23

Dinoflagellates

Answer 23

2 (transverse & longitudinal) flagella with different insertion points on the cell

Question 24

Apicomplexans

Answer 24

• Obligate parasites of animals
• Contain apicoplasts
• Ex: Plasmodium (malaria)

Question 25

Apicoplats

Answer 25

Degenerate chloroplasts that lack pigments & phototrophic capacity, but still carry many anabolic pathways

Question 26

Stramenophiles: General characteristics

Answer 26

All have flagella with many short hairlike extensions

Question 27

Oomycetes (water molds)

Answer 27

* Filamentous growth & the presence of coenocytic hyphae * Cell walls are made of cellulose

Question 28

Golden algae (chrysophytes)

Answer 28

Chloroplasts are dominated by fucoxanthin which gives it its golden-brown colour

Question 29

Diatoms

Answer 29

Characteriste by frustules (cell walls made of silica)

Question 30

Frustules | Diatoms

Answer 30

Cell walls made of silica with proteins & polysaccharides attached to it

Question 31

Rhizaria

Answer 31

Distinguished by their threadlike pseudopodia

Question 32

Foraminifera

Answer 32

Form shell-like structures called tests made from OM reinforced with calcium carbonate

Question 33

Radiolarians

Answer 33

* Tests are made of silica * Name derived from radial symmetry of tests

Question 34

Amoebozoa

Answer 34

Use pseudopodia for movement & feeding

Question 35

Gymnamoebas

Answer 35

* Unicellular * Free-living in soil & aquatic environments

Question 36

Entamoebas

Answer 36

* Unicellular * Parasites of vertebrates and invertebrates

Question 37

Slime Mold: Types

Answer 37

* Plasmodial slime molds * Cellular slime molds

Question 38

Plasmodial slime molds

Answer 38

* Masses of protoplasm of indefinite size & shape that contain multiple nuclei (vegetative form) * Sporangium forms containing haploid spores * Spores germinate, yielding a swarmer cell * Fusion of 2 swarmer cells regenerates the diploid plasmodium

Question 39

Cellular slime molds | Life cycle?

Answer 39

* Single amoebae (haploid) (vegetative form) * Aggregate as a pseudoplasmodium * Fruiting body is formed, cells differentiate into spores * Form diploid macrocysts * Macrocysts undergo meiosis to form new amoebae (haploid)

Question 40

Opisthokonta: Fungi

Answer 40

* Most fungi are multicellular * Cell walls are made of chitin * Extracellular digestion

Question 41

Coenocytic

Answer 41

Cytoplasm and nuclei are not subdivided into cells (multinucleated)

Question 42

Septate

Answer 42

Nuclei are separated by cross wall

Question 43

Ectomycorrhizae

Answer 43

Form a sheath around the plant root but does not penetrate it

Question 44

Endomycorrhizae

Answer 44

The fungal hyphae is embedded in the plant root

Question 45

Haustoria

Answer 45

Specialized fungal hyphae that penetrate plant cells & consume the cytoplasm

Question 46

Mycoses

Answer 46

Human diseases caused by a fungus

Question 47

Fungi: Reproduction

Answer 47

Asexual (most common): * Growth and spread of hyphal filaments * Asexual production of spores called conidia * Simple cell division (budding) Sexual: * Fusion of 2 haploid cells to form diploid cell * Diploid cell undergos meiosis to produce haploid spores * Spores are resistant to drying, heating, freezing, chemicals