Eukaryotes

Key Derived Traits

• nucleus

• membrane bound organelles

• well developed cytoskeleton

Well developed cytoskeleton

• network of fibers within cell

• support, allows for asymmetry and changing shape

Endosymbiosis

relationship between 2 species where 1 species lives inside the other

Serial Endosymbiosis

series of endosymbiotic events

Primary endosymbiosis

phagocytosis of bacterium by larger cell

Mitochondria (1st)

alpha proteobacteria within archaea

Chloroplasts (later)

Cyanobacteria within heterotrophic eukaryotes

Secondary endosymbiosis

bigger eukaryote engulfs smaller secondary (2º plastids)

Plastid

general term for chloroplasts and related organelles

1º endosymbiosis

chloroplasts derived from cyanobacteria

2º endosymbiosis

2º plastids derived from red or green algae

1º endosymbiosis process

heterotrophic eukaryotes with mitochondria engulfs cyanobacteria

2º endosymbiosis process

heterotrophic eukaryotes engulfs green algae

Eukaryote Diversity

• mostly unicellular

• many colonial or multicellular

• complex cellular organization

• many nutritional strategies

• diverse life cycles

Mixotrophs

capable of photosynthesis and heterotrophy

Ancestral Eukaryotic traits

• nucleus, membrane-bound organelles

• aerobic respiration

• mitochondria from 1º endosymbiosis

Archaeplastida

• Chloroplasts via 1º endosymbiosis

• red, green algae, and land plants that are all photosynthetic

Red Algae

• primary multicellular and often highly branched

• color due to phycoerythrin

• many live very deep ~ 30m down warm tropical water

Green Algae

• closely related to land plants

• many forms → unicellular, colonial

Chlorophytes

mostly freshwater, and simple (unicellular)

Charophytes

sister groups to plants

SAR

• 2º endosymbiosis of red algae

• 3 major clades

  • strameopiles

  • alveolates

  • rhizarians

Amoebozans

• typical “blob” shape

• lube or tube shaped pseudopodia

Opisthokonta

• diverse

• animals, fungi, several groups of protists

• nuclearids

• choanoflagellates

Nuclearids

protists, closely related to fungi

Choanoflagellates

unicellular, closely related to animals

Discoba

• extremely diverse

• shared derived traits → crystalline rod in flagella

• some have 2º plastids via green algae → mixotrophic

• trypanosomes

• euglenoids

Trypanosomes

often pathogenic

Euglenoids

often mixotrophic