Biology 2581B Study Guide - Quiz Guide: Red Algae, Heterokont, Unikont
Eukaryotic Diversity
Origins of Eukaryotes
→ The earliest known cells had prokaryotic organisation
→ Thought that mitochondria and chloroplasts are probably descendants of bacteria that were
engulfed by a large host cell during a process called endosymbiosis
→ First eukaryotes were unicellular organisms and now they are found as both unicellular and
multicellular organisms
Diversity of Eukarya
→ Multicellular groups animals, plants and fungi are all in the Domain Eukarya but most species
in Eukarya are unicellular organisms
→ Some unicellular eukaryotes are not classified as animals, plants, or fungi – protists
→ Protista = old name for unicellular eukaryotes, no longer valid taxon
Structural and Functional Diversity
→ Huge variation in what eukaryotes look like and what they do
→ Unicellular and multicellular species
→ Cells of unicellular species may be large and complex
→ Phototrophs (chloroplasts to make food from light), heterotrophs (ingests food), or both at
once
→ Cell walls, rigid shell/skeleton, or neither
The Kingdoms of Eukarya
→ Animalia, Plantae, and Fungi
→ Animals – all vertebrates including fish and birds, all invertebrates including insects, starfish
etc, multicellular (ingestive nutrition), not Protists (protozoa) as unicellular
→ Plants – land and aquatic plants (multicellular, green), may include green algae (multicellular
and unicellular)
→ Fungi – not including filamentous prokaryotes
Eukarya Supergroups
→ Excavata (Diplomonads, Parabasalids, Euglenozoans) – Giardia intestinalis (diarrhoea),
Trypanosoma brucei (sleeping sickness), Euglena (photosynthetic pond dweller)
→ Archaeplastida (red algae, green algae, land plants) – all have chloroplasts derived from
cyanobacteria, red/green algae include multicellular seaweeds and colonial forms as well as
unicellular species (important aquatic photosynthesisers), land plants (Plantae) belong here
→ ‘SAR’ Clade (Stramenopiles, Alveolates, Rhizarians) – Plasmodium vivax – apicomplexan
(malaria), Paramecium – ciliate (pond dweller)
→ Unikonta (Amoebozoans, Opisthokonts) – fungi belong here (with closest unicellular
relatives), Animals belong here (with closest unicellular relatives), slime molds, most
amoebae (free-living and parasitic)
WHAT TO REMEMBER:
→ What is a eukaryote?
Document Summary
The earliest known cells had prokaryotic organisation. Thought that mitochondria and chloroplasts are probably descendants of bacteria that were engulfed by a large host cell during a process called endosymbiosis. First eukaryotes were unicellular organisms and now they are found as both unicellular and multicellular organisms. Multicellular groups animals, plants and fungi are all in the domain eukarya but most species in eukarya are unicellular organisms. Some unicellular eukaryotes are not classified as animals, plants, or fungi protists. Protista = old name for unicellular eukaryotes, no longer valid taxon. Huge variation in what eukaryotes look like and what they do. Cells of unicellular species may be large and complex. Phototrophs (chloroplasts to make food from light), heterotrophs (ingests food), or both at once. Animals all vertebrates including fish and birds, all invertebrates including insects, starfish etc, multicellular (ingestive nutrition), not protists (protozoa) as unicellular. Plants land and aquatic plants (multicellular, green), may include green algae (multicellular and unicellular)