Lecture 8

Question 1

symbiotic relationships

Answer 1

occur when members of two species live in close, often obligatory, contact with each other - mutualism, competition, commensalism, amensalism, predation, parasitism

Question 2

host

Answer 2

larger organism in symbiotic relationship

Question 3

symbiont

Answer 3

smaller organism in symbiotic relationship

Question 4

endosymbiotic

Answer 4

inside host organism

Question 5

oldest fossil eukaryote

Answer 5

1.8 BYA

Question 6

4 eukaryotic cell characteristics

Answer 6

1. DNA in linear chromosomes in membrane-bound nucleus
2. other membrane-bound organelles such as mitochondria and plastids (chloroplasts)
3. often larger than prokaryotes
4. cytoskeleton allows them to change shape

Question 7

ancestral pre-eukaryotic cell

Answer 7

possibly a member of Archaea

Question 8

origin of eukaryotic cell

Answer 8

ancestral host cell developed some structures (endoplasmic reticulum, nuclear envelope) gradually by infoldings of cell membrane, then the ancestral host cell took on an endosymbiotic aerobic heterotrophic prokaryote

Question 9

proteobacterium

Answer 9

endosymbiotic aerobic heterotrophic prokaryote, used oxygen and organic matter to make energy, eventually became mitochondrion

Question 10

origin of photosynthetic protists and plants

Answer 10

eukaryotes engulfed photosynthetic prokaryotes (cyanobacteria), became plastids

Question 11

serial endosymbiosis

Answer 11

first mitochondria and then plastids were endosymbiotically acquired by the ancestors of photosynthetic eukaryotes

Question 12

3 evidences for endosymbiosis in evolution of eukaryotes

Answer 12

1. mitochondria and chloroplasts have own DNA, replicated independently
2. this DNA is circular like prokaryotic DNA
3. plastids have 2 or more cell membrane layers

Question 13

primary endosymbiosis

Answer 13

free-living prokaryote being taken on by another cell - eg. red and green algae

Question 14

secondary endosymbiosis

Answer 14

taking on a photosynthetic (plastid-containing) eukaryotic cell by a heterotrophic eukaryotic cell, engulfed red or green algae

Question 15

horizontal gene transfer through endosymbiosis

Answer 15

make tree of life very complicated

Question 16

first wave of diversification

Answer 16

metabolic diversification of prokaryotes

Question 17

second wave of diversification

Answer 17

catalyzed by greater structural diversity of eukaryotic cell

Question 18

third wave of diversification

Answer 18

origin of multicellular bodies

Question 19

new ways of reproduction in eukaryotes

Answer 19

mitosis, meiosis, and syngamy

Question 20

mitosis

Answer 20

one diploid cell divides once to form two diploid (2n) cells

Question 21

meiosis

Answer 21

one diploid cell divides twice to form four haploid (1n) cells (reduction division)

Question 22

syngamy

Answer 22

occurs when two 1n gametes fuse, form 2n zygote (fertilized egg)

Question 23

embryo

Answer 23

multicellular, formed when zygote grows by mitotic cell division

Question 24

larval stage

Answer 24

morphologically different stage before reproductively mature adult

Question 25

sexual reproduction

Answer 25

two parents produce offspring with novel combinations of genes from both parents, requires meiosis and subsequent fusion of haploid nuclei from different parents

Question 26

protists

Answer 26

the common name for a non-monophyletic group of mostly unicellular eukaryotes that are not plants, fungi or animals

Question 27

protist characteristics

Answer 27

phototrophic/heterotrophic/mixotrophic, diverse reproductive modes, single-celled

Question 28

mixotrophic

Answer 28

both photoautotrophic and heterotrophic

Question 29

5 groups of protists (basal polytomy)

Answer 29

1. diplomonads 2. apicocomplexans 3. ciliates 4. amoebozoans

Question 30

diplomonads

Answer 30

"primitive" protists, appear to lack mitochondria, but mitosomes and mitochondrial genes are present, suggests that they ancestrally had regular mitochondria but lost them during evolution, found in anaerobic habitats, multiple flagella, two separate nuclei

Question 31

Giardia duodenalis

Answer 31

type of diplomonad, infects human intestines causing diarrhea, from contaminated drinking water, beaver fever, has mitosomes

Question 32

apicocomplexans

Answer 32

parasites of animals, complex of organelles for penetrating host tissues at apex of cell, organelles have 4 membranes and cyanobacterial DNA; evidence of secondary endosymbiosis, often require 2 or more host species to complete life cycle

Question 33

Plasmodium spp.

Answer 33

apicocomplexan parasites that cause malaria, need mosquitoes and vertebrates, resistant mosquitoes and plasmodium have caused malarial resurgence

Question 34

ciliates

Answer 34

large and morphologically diverse group named for the presence of many cilia used for locomotion and/or food capture, free-living species feed on bacteria and smaller protists by phagocytosis, some very active move on fused leg-like cilia, reproduce asexually by binary fission, sometimes engage in sexual reproduction (conjugation)

Question 35

ciliate example

Answer 35

Paramecium

Question 36

amoebozoans

Answer 36

flexible body shape that move by extending blunt | lobes called pseudopodia and feed by phagocytosis, may be related to unikonta

Question 37

3 groups of amoebozoans

Answer 37

1. amoebae 2. plasmodial slime molds 3. cellular slime molds

Question 38

plasmodial slime molds

Answer 38

start out with a single nucleus but then undergo repeated mitosis without cell division, become a single giant supercell with free-flowing cytoplasm and nuclei that hunts bacteria on the forest floor

Question 39

amoebae

Answer 39

amorphous solitary protists, mainly predators of bacteria and smaller protists

Question 40

cellular slime molds

Answer 40

start out as separate single-celled individuals, if food becomes scarce, cells get together but maintain separate cell membranes, communal ‘slug’ migrates to a high spot, some cells form stalk, other cells climb up stalk and develop hard coat to withstand drying, disperse in the wind and land somewhere wet, helpful cells that formed the stalk die

Question 41

algae

Answer 41

general term for photoautotrophic eukaryotes that are not members of the Kingdom Plantae, not monophyletic, single-celled (diatoms), or multicellular (brown algae, alternation of generations)

Question 42

diatoms

Answer 42

major components of marine and freshwater plankton

Question 43

brown algae

Answer 43

kelp and other seaweeds

Question 44

green algae

Answer 44

have green pigments in chloroplasts, chlorophytes and charophytes (multicellular and morphologically complex, thought to be sister to Plantae)

Question 45

Chara

Answer 45

common charophyte lakeweed in Alberta