Eukaryotes (Topic 3)

Characteristics of Eukarya

* DNA in a nucleus
* membrane-bound organelles
* cytoplasm
* small (typically 10-100 μm)
* single celled, communities, or multicellular
* primary endosymbiosis of mitochondria

Polytomy

Eukaryotic tree is a…

Endosymbiont Theory

Theory that states that some of the organelles in eukaryotes (ex: mitochondria, chloroplasts) were once prokaryotic microbes (ex: alpha proteobacterium, cyanobacterium)

Endosymbiosis

When an organism engulfs another organism & benefits from it (ex: mitochondria)

Serial endosymbiosis

When endosymbiosis happens in series

Primary endosymbiosis of mitochondria

Aerobic alpha proteobacterium (aerobic) engulfed within archaea (anaerobic)

Primary endosymbiosis of chloroplast

* Cyanobacteria engulfed within heterotrophic eukaryote
* Led to ancestor of red & green algae

Homologous

Possessing a mitochondria is a __________ characteristic for Eukarya

Plastids

* Organelles that result from secondary endosymbiosis
* general term for chloroplasts & related organelles
* secondary ________ derived from red or green algae (eukaryotes) via secondary endosymbiosis

Protists

* “the very first” arose through endosymbiosis
* general word for all eukaryotes but traditionally does not include plants, animals, or fungi
* very diverse
* many unicellular
* many nutritional strategies
* life cycles vary

Archaeplastida, SAR, Amoebozoa, Opisthokonta, Discoba

5 Eukaryotic Supergroups

Archaeplastida

* “ancient plastids”
* shared ancestral trait: primary endosymbiosis of a chloroplast
* Groups
* red algae
* green algae: chlorophytes, charophytes
* plants (embryophytes)

Red Algae

* red color pigment ==phycoerythrin==
* usually multicellular
* ex: seaweeds, sushi!
* basal of Archaeplastida

Phycoerythrin

Red color pigment for red algae

phyco = seaweed

erythro = red

Green Algae

* two groups: chlorophytes, charophytes
* closely related to plants (embryophytes)

SAR

* shared derived traits:
* genetic characteristics
* secondary endosymbiosis of red algae
* Groups
* Stramenopiles
* Alveolates
* Rhizaria

Stramenopiles

* Derived traits:
* long “hairy” flagellum & shorter “smooth” flagellum
* many are photosynthetic algae (have chloroplasts)
* most single celled, some multicellular

Alveolates

* Derived traits:
* alveoli: flattened vesicles just inside PM
* support membrane
* associated with malaria

Rhizaria

* derived trait: skeletal structure of calcium or silica
* ex: foraminiferans (forams tests: porous shells made of calcium carbonate)

Amoebozoa

* Derived traits:
* pseudopodia
* lobe-shaped or tube-shaped

Opisthokonta

* Derived traits: cell with a flagellum
* Nucleariids & Fungi: sisters
* Choanoflagellates & Animals (Metazoa): sisters

Discoba

* Derived trait: secondary endosymbiosis of green algae
* ex: euglenozoans