biol 215 groups

Protists

• Mostly unicellular eukaryotes

• Include parasitic, photosynthetic, heterotrophic forms

• Between 12-32 phyla

• Artificial group

Excavates

• Diverse group (no real common feature other than uni cell and many having feeding groove)

• Thought to be ancestor of other eukaryotes (all had mito at one time but some lost them, seen through mito proteins in genome)

• Parasitic organisms

• Flagellated, obligate anaerobes

Examples of Excavates

• Trichonympha (termite gut)

• Entamoeba hystolytica (hiker’s diarrhea)

• Trypanosoma (sleeping sickness; kinetoplastid)

Chromalveolates

• Supergroup containing 23 previous groups (algae and some non-photosynthetic groups)

• Includes dinoflagellates, apicomplexa, ciliates, brown algae, and diatoms

• Some human parasites

• Important primary producers and consumers of planktonic communities of lakes and oceans

• Includes both photosynthetic and non-photosynthetic organisms

Chromalveolates Sub-groups

• Dinoflagellates

• Apicomplexa

• Stramenopiles

• Cryptomonads

Dinoflagellates

• Heterotrophic and phototrophic species

• Many form dormant cyst stage

• Some species are symbionts of invertebrates (coral)

• Red tides (paralytic and hemolytic shellfish poisoning)

Apicomplexa

• Obligate parasites of animals

• Complex life cycles

• Have an apical complex of organelles that help them attach to or penetrate their host

• Malaria (finish mosquito life cycle)

Stramenopiles

Diatoms, oomycetes, and phaeophyta

Diatoms

• 1000 species found in all aquatic environment

• Responsible for 25% of global primary production

• Produce silica (glass) exoskeleton known as a frustule

• Only male gametes have flagellum

• Base of food chain and leads to all major fisheries in ocean

Oomycetes

• Water molds (formerly classified as a fungi)

• Filamentous growth form, but produce flagellated zoospores (asexual spores that give rise to filaments)

• Causes many ag disease (Irish potato famine; moldy wine grapes)

Phaeophyta

seaweeds; brown algae with no unicell reps

Rhizaria

• United only by molecular data

• Heterotrophic unicells that consume prokaryotes and eukaryotes

• Produce CaCO3 exoskeleton with many pores

• Extend cytoplasmic extensions (pseudopodia) through pores and shells to prey items

Archaeplastida

• Plantae

• Include red and green algae, land plants, and charophytes

• All contain plastids arose by primary endosymbiosis

• Sexual reproduction common

• Unicells, colonial, and multicell forms

Chlorophyta

• Chromalveolate

• Most advanced forms have reproductive features like those of higher plants

• Includes chlamydomonas & chara

Chlamydomonas

• Unicells

• A model organism for evolution, molecular, physiological and biochemical studies

Chara

• Has distinct reproductive structures that contain eggs (oocyte)

• Land plants thought to be derived from Charophytes

Unikonts

• Contains parasitic protists, slime molds, amoebae, animals, and fungi

• Includes choanoflagellates

• 600 mya multicell organisms appear (coinciding with dramatic rise in O2 in atmosphere)