Chapter 25: The Origin/Diversification of Eukaryotes Flashcards
What are Eukaryotic cells?
cells that contain membrane-enclosed nucleus/organelles
What are the four subgroups of Eukaryotes?
Excovata, SAR, Archaeplastida, Unikonta
What characteristics do Eukaryotic cells have?
-A membrane-enclosed nucleus
-Membrane-bound organelles
-Cytoskeleton
-Linear DNA
What is a Pairwise Comparison Matrix?
compares genetic sequences for rRNA% similarity in sequences
What kind of organisms are Eukaryotes?
“Combination” with some genes/characteristics derived from Archaea and Bacteria
Which bacteria is most similar in rRNA to mitochondria?
A. tumefaciens
What is endosymbiosis?
a symbiotic relationship in which one organism lives inside the body/cell of another.
How did the rise of Eukaryotes begin?
An Archaeal cell engulfed a Bacterial cell that would later become an organelle found in all eukaryotes (the mitochondrion)
What is the Endosymbiont Theory?
Mitochondria and plastids were formerly small bacteria that began living within larger cells
How did Bacterial symbionts originate in Archaeal host cells?
Through undigested prey and internal parasites
What is the evidence of endosymbiotic origin of mitochondria/plastids?
- Inner membranes have transport systems like those of plasma membranes in living bacteria.
- Mitochondria/plastids undergo binary fission.
- DNA is circular.
- Have their own cellular machinery to transcribe/translate DNA to protein.
- Ribosomes are more like those of bacteria than those of ribosomes in the cytoplasm of Eukaryote cells.
What conditions would result in selection for an aerobic endosymbioant?
An anaerobe living in an env’t with increasing 02
What Eukaryotes have plastids?
Algae, photosynthetic protists, and all photosynthetic eukaryotes EXCEPT plants
Did Plastid Evolution by secondary endosymbiosis create a lot of diversity?
Yes
What are the oceanic primary producers?
Algae + cyanobacteria
Is NPP high or low in oceans?
Low
What did the 1st wave of eukaryotic diversification bring?
Greater complexity of unicellular forms
What did the 2nd wave of eukaryotic diversification bring?
The evolution of multicellularity
What are the two steps to multicellularity?
The formation of colonies and differential cells
Why are special mechanisms required for animals?
enables the cells to adhere and communicate with each other
What are choanoflagellates?
-the closest living protist to humans
-all unicellular or colonies
-have homologous mechanisms for adherence and signaling
What defines the supergroup of Excavata?
Species that have excavated feeding groove
What are the subgroups of Excavata?
Diplomonads/Parabasalids + Evglenozoans
What defines a Diplomonad/Parabasalid?
-having a reduced mitochondria
-are anaerobic
-Many being parasitic
What defines a Evglenozoan?
-A diverse clade
-are heterotrophs, photosynthetic autotrophs, parasites
-Have a presence of a rod with crystalline structure inside of the flagella
What defines the supergroup of SAR Stramenopiles?
-secondary endosymbiosis
-important photosynthetic organisms
What are the subgroups of SAR Stramenopiles?
Diatoms + Brown Algae
What defines the supergroup of SAR Alveolates?
-membrane-enclosed sacs (alveoli)
-secondary endosymbiosis
-photosynthetic/heterotrophic
What defines a Diatom?
-unicellular algae
-highly diverse
-unique wall structure of silicone dioxide
What defines Brown Algae?
-largest and most complex algae
-multicellular
-marine
-lack true tissues/organs
What defines a Dinoflagellate?
-spin as they move
-mixotrophs
-some produce toxins
What are the subgroups of SAR Alveolates?
Dinoflagellate + Ciliates
What defines a Ciliate?
-cilia to move/feed
-predatory
What defines the supergroup SAR Rhizarians?
-amoebas and flagellated non-amoeboids
-pseudopodia
What are the subgroups of SAR Rhizarians?
Forams + Cercozoans
What defines a Foram?
-tests with little holes
-symbiotic algae in tests
-single-celled
What defines a Cercozoan?
marine, freshwater, soil
-parasitic, predators, mixotrophs
What defines the supergroup of Archaeplastids?
-Red algae
-green algae
-plants
What defines red algae?
-Reddish pigment masks chlorophyll
-survive in deeper depths
-multicellular
-photosynthetic and heterotrophs
What defines green algae?-
-similar chloroplasts to plants
-Charophytes
-Chlorophytes
What defines the supergroup of Unikonta Amoebozoans?
-unicellular
-multicellular (slime molds)
What makes up Unikonta Amoebozoans?
Tubulinids + slime molds
What defines a Tubulinid?
-unicellular
-Heterotrophs (some feed on detritus)
-soil, freshwater, marine
What defines a slime mold?
-produce fruiting bodies
-Feeding stage–> solitary cells
-reproductive stage–> aggregate
What are the 4 Eukaryotic supergroups?
Excavata, SAR, Archaeplastids, and Unikonta
