Protists and Fungi

*    2 Diverse Kingdoms of Life

 

Domain Eukarya

*    Eukaryotes (review BIOL 1020 notes)

*    Differ from other domains by:

*    1) multicellularity: body formed of cells which are in contact and coordinate activities

*    Note some eukaryotes are unicellular or colonial (aggregation of cells with little coordination of activities)

*    2) sexual reproduction: absent from all bacteria known

*    Note some eukaryote groups rarely or never reproduce sexually (only asexual reproduction has been observed)

 

*    But, evolution of eukaryotes involved endosymbiosis, incorporation of Eubacteria cells into eukaryotes as mitochondria and chloroplasts.

Domain Eukarya

*    The mitochondria of all eukaryotes, and the chloroplasts of photosynthetic ones, evolved from Eubacteria. 

Domain Eukarya

*    The mitochondria of all eukaryotes, and the chloroplasts of photosynthetic ones, evolved from Eubacteria. 

Domain Eukarya
Kingdom Protista (protists)

*    Most diverse kingdom in Eukarya

*    Unicellular (single cells)

*    Colonial (loose confederations of cells which generally do not coordinate activities or specialize to perform particular functions)

*    Multicellular (many cells that do coordinate activities and often become specialized to divide up life functions)

Domain Eukarya
Kingdom Protista (protists)

*    Artificial group: not based on phylogeny

*    Placed together for convenience and because they are NOT fungi, animals, or plants

*    Polyphyletic group

 

*    Note that classifications

*    vary: text and lab use

*    different systems!

Kingdom Protista (protists)

*    We will cover them by grouping similar phyla together into 5 general groups:

*    Heterotrophs with no permanent locomotor apparatus

*    Photosynthetic ones

*    Heterotrophs with flagella

*    Non-motile spore-formers

*    Heterotrophs with restricted

*     mobility.

1) Heterotrophs with no permanent locomotor apparatus

*    Mostly unicellular and ameoba-like:

 

*    Phylum Rhizopoda (amoebas)

*    Phylum Actinopoda (radiolarians)

*    Phylum Foraminifera (forams).

Phylum Rhizopoda (amoebas)

*    Move by pseudopods (flowing extensions of cytoplasm)

*    Lack sexual reproduction, cell walls, flagella

*    Reproduce asexually only

Phylum Rhizopoda (amoebas)

*    Many are predators (use pseudopods to engulf other cells).

*    Exception: Vampyrella, the "sucking amoeba"

*    Sucks contents of algal cell in matter of seconds.

Phylum Rhizopoda (amoebas)

*    Hundreds of species: freshwater, marine, soil

*    Some are parasites (feed on host tissues or cells but usually donšt kill host).

Phylum Rhizopoda (amoebas)

*    Example: Entamoeba histolytica (cause of amoebic dysentery)

*    Up to 10 million Americans may be infected by parasitic amoebas.

Phylum Actinopoda (radiolarians)

*    Have shells (external skeletons) made of silica (glass)

*    Pseudopods needle-like

*    Marine group. Part of plankton (microscopic floating marine organisms)

*    Valuable fossils for geological record.

Phylum Foraminifera (forams)

*    Marine, make skeleton (called test) of organic material plus sand, calcium carbonate

*    Some float in plankton, most live attached to bottom or other organisms

*    Podia (thin cytoplasmic projections) used for swimming, feeding.

 

Phylum Foraminifera (forams)

*    Life cycle: sporic meiosis (haploid and diploid generations formed)

*    Important fossil group (200 million years of geological record

*    Limestones often rich in forams (ex, Dover, England).

2) Photosynthetic protists

*    Phylum Phyrrhophyta (dinoflagellates)

*    Phylum Euglenophyta (euglenoids)

*    Phylum Chrysophyta (diatoms and golden algae)

*    Phylum Rhodophyta (red algae)

*    Phylum Phaeophyta (brown algae)

*    Phylum Chlorophyta (green algae)

Phylum Phyrrhophyta (dinoflagellates)

*    Unicellular, mostly marine: 2100 species

*    Usually 2 flagella, skeleton of plates of cellulose

*    Reproduce mostly by asexual reproduction (sex rare)

*    Chlorophylls a + c

Phylum Phyrrhophyta (dinoflagellates)

*    Important/interesting roles:

­  zooxanthellae: symbionts (live in mutually beneficial relationship) in other organisms (jellyfish, sea anemones, mollusks, corals)

­  Zooxanthellae in corals (up to 30,000 cells per cubic mm or coral tissue) do photosynthesis and carbon products absorbed by corals, helping to make coral reefs one of most productive habitats on Earth!.

Phylum Phyrrhophyta (dinoflagellates)

*    Important/interesting roles:

­  bioluminescent: emit light when disturbed

­  creates sparkling waves and wakes of ships at night

­  why do this? Perhaps to attract predatory fish to eat the predators of the dinoflagellates!

Phylum Phyrrhophyta (dinoflagellates)

*    Important/interesting roles:

­  red tides: population explosions ("blooms") that can color the water with pigmented dinoflagellate cells

­  toxins in cells can kill marine life

­  Example, Pfiesteria piscicida: stuns fish with toxin and feeds on body fluids.

Phylum Euglenophyta (euglenoids)

*    Mostly freshwater, unicellular. 1000 species

*    Some photosynthetic (chlorophylls a + b), some not

*    Protein coat called pellicle on outside of cell

*    Important members of food freshwater food chains

*    Example, Euglena.

Phylum Chrysophyta (diatoms and golden algae)

*    Here we emphasize the diatoms: 11,500 species

*    Use chlorophyll a + c, lack flagella

*    Make chrysolaminarin: unique energy storage chemical

*    Cell wall of silica

*    (glass), with intricate

*     designs. Like petri

*    plate, with top and

*    bottom halves.

 

Phylum Chrysophyta

*    Asexual reproduction common, but do gametic meiosis.

*    Importance:

­  1) "grass of the sea." Abundant members of plankton. Do large % of ocean photosynthesis

­  2) fossil deposits of cell walls called "diatomaceous earth." Mined and used for pest control (applied to insects, gets in appendages and grinds them to death), reflective paints, filters.

Phylum Rhodophyta (red algae)

*    Mostly marine (many tropical), multicellular. 4000 species.

*    Lack flagella

*    Have only chlorophyll a: similar to photosynthetic bacteria called cyanobacteria

*    Reproduction: mostly sporic meiosis (make gametophyte and sporophyte generations).

Phylum Rhodophyta (red algae)

*    Importance:

­  Coral reefs: part of reef made of coralline red algae, which have calcium carbonate forming part of cell walls.

 

Phylum Rhodophyta (red algae)

*    Importance:

­  Agar and carrageenan (cell wall chemicals) are extracted from some red algae

­  Used as emulsifiers and thickeners (chocolate milk, ice cream, cosmetics, jellies, microbiology medium, etc.)

 

Phylum Phaeophyta (brown algae)

*    Marine (cold water), multicellular: 1500 species

*    Chlorophylls a + c

*    Reproduction often sexual: sporic meiosis (sporophyte and gametophyte generations)

 

 

Phylum Phaeophyta (brown algae)

*    Large species called kelps

*    Form "kelp forests": important shallow water habitats.

 

Phylum Phaeophyta (brown algae)

*    Kelps also harvested for cell wall materials called alginates: used as thickeners in foods and other products.

 

Phylum Chlorophyta (green algae)

*    Mostly aquatic (some on most terrestrial surfaces), marine and freshwater: 7000 species

*    Unicellular to multicellular

*    Chlorophylls a + b

 

Phylum Chlorophyta (green algae)

*    Unicellular motile example: Chlamydomonas

*    To be seen in lab: note zygotic meiosis and asexual reproduction in haploid phase.

 

Phylum Chlorophyta (green algae)

*    Motile (swimming) colonial example: Volvox

*    To be seen in lab: note daughter colonies (made asexually inside main sphere).

 

Phylum Chlorophyta (green algae)

*    Parenchymatous (3-D body) form: Ulva (sea lettuce)

*    To be seen in lab: note life cycle is sporic meiosis where gametophyte and sporophyte look identical (isomorphic alternation of generations)!

 

Phylum Chlorophyta (green algae)

*    Importance:

­  producers in aquatic ecosystems (base of food chains)

­  human/animal nutritional supplement? Chlorella in the news....

 

Phylum Chlorophyta (green algae)

*    Evolutionary Importance

*    Land plants (Kingdom Plantae) evolved from a line of green algae.

 

3) Heterotrophs with flagella

*    Phylum Sarcomastigophora (zoomastigotes)

*    Phylum Ciliophora (ciliates)

 

Phylum Sarcomastigophora (zoomastigotes)

*    Mostly unicellular, often with flagella

*    Here we emphasize Class Zoomastigophora, especially a group called the trypanosomes

*    Most reproduction is asexual.

Phylum Sarcomastigophora (zoomastigotes)

*    Some trypanosomes are parasites that cause serious human diseases:

­  African sleeping sickness: Caused by Trypanosoma

­  Carried to new host by biting fly (tsetse fly)

­  Affects cattle and prevents livestock culture in large area of Africa.

Phylum Sarcomastigophora (zoomastigotes)

*    Some trypanosomes are parasites that cause serious human diseases:

­  Leishmaniasis (caused by Leishmania)

­  Carried to new host by biting fly (sand fly) in tropical areas

­   Causes sores and erosion of skin (4 million people/yr).

Phylum Sarcomastigophora (zoomastigotes)

*    Some trypanosomes are parasites that cause serious human diseases:

­  Giardiasis caused by Giardia lamblia

­  Infects humans and some other animals (dogs). Found across U.S.

­  Causes nausea, cramps, diarrhea.

Phylum Sarcomastigophora (zoomastigotes)

*    Some trypanosomes are gut symbionts:

­  Trichonympha in guts of termites (Order of insects)

­  Digest cellulose in wood for insect, receive home in gut.

Phylum Ciliophora (ciliates)

*    Unicellular (but some big and internally complex)

*    8000 species

*    Most with many cilia

*    Also have 2 types of nuclei: macronucleus (large) and micronucleus (small)

*    Outer covering (called pellicle) of tough protein material

Phylum Ciliophora (ciliates)

 

*    Do sexual reproduction by conjugation (exchange of micronuclei).

 

Phylum Ciliophora (ciliates)

*    Examples, Paramecium and Stentor

*    Cilia used for locomotion and for feeding.

4) Nonmotile spore-formers

*    Phylum Apicomplexa (sporozoans)

Phylum Apicomplexa (sporozoans)

*    Unicellular, do not make cilia/flagella: 3900 species

*    All are parasites of animals

*    Spores are infective bodies used to reach new hosts

*    Cell structure unique: on end (apex) of cell has concentration of organelles.

Phylum Apicomplexa (sporozoans)

*    Example, Plasmodium

*    Cause of malaria

*    Complex life cycle: uses mosquito and human as host

*    One of most serious diseases worldwide: 500 million cases/yr (2 million deaths).

 

 

 

*    Attacked by mosquito control (often insecticides) and antimalarial drugs

*    Problem: both mosquitoes and Plasmodium evolve resistance to control chemicals

*    Maybe develop vaccine?.

5) Heterotrophs with restricted mobility

 

*    Phylum Oomycota (oomycetes)

*    Phylum Acrasiomycota (cellular slime molds)

*    Phylum Myxomycota (plasmodial slime molds)

Phylum Oomycota (oomycetes)

*    All are parasites or saprobes (feed on dead organic matter). About 600 species

*    Cell walls present (cellulose)

*    Gametic life cycles (like us!)

*    Make asexual spores by mitosis: called mitospores. As with all spores, one can form new organism without joining with another cell. If swimming mitospore, called a zoospore.

*    May form threadlike cells

­  One called hypha (pl. hyphae).

Phylum Oomycota (oomycetes)

*    Importance: some cause diseases of plants or fish

*    Example, late blight of potato (Phytophthora).

Irish Potato Famine

*    Irish peasants depended on potatoes as staple food

*    1845-1847, late blight of potato struck

*    Destroyed crops

*    1 million Irish starved to death, 1 million emigrated (many to U.S.).

Phylum Acrasiomycota
(cellular slime molds)

 

*    Weird group: 70 species.

*    Amoeboid cells

*    Join together for form mass called "slug"

*    Makes spores.

Phylum Myxomycota
(plasmodial slime molds)

*    Another weird group (700 species). Plasmodium is multinucleate mass of cytoplasm

*    Flows around in moist areas, ingesting unicells and organic matter

*    Example, Physarum.

Phylum Myxomycota
(plasmodial slime molds)

*    Later form meiospores with cellulose walls

*    Note a spore-containing structure often called a "sporangium" ("angios" from Greek for "vessel")

*    Plural is sporangia.

Kingdom Fungi

*    Unlike Protista, are monophyletic group

*    Large: about 77,000 named species

*    Many more remain to be discovered.

 

General fungal traits

*    Terrestrial heterotrophs (digestion is external: enzymes secreted and food absorbed from solution)

*    Cell walls of chitin

*    Unique type of mitosis (nuclear mitosis: where nucleus divides within nuclear membrane)

*    Do not make swimming cells (lack cilia and flagella)

*    Reproduce by spores

­  sexual spores are meiospores (formed by meiosis)

­  asexual spores are mitospores (formed by mitosis).

 

General fungal traits

*    Most cells are threadlike and tubular (hyphae)

­  Mass of hyphae called mycelium.

General fungal traits

*    Some hyphae lack crosswalls (coenocytic hyphae)

 

 

 

 

*    Some hyphae have crosswalls (septate hyphae)

 

General fungal traits

*    Sexual reproduction: zygotic meiosis

*    Haploid phase predominates

*    BUT, syngamy fertilization has 2 steps

­  Plasmogamy: union of gamete cells

­  Karyogamy: union of gamete nuclei

*    Some fungi do plasmogamy but delay karyogamy, forming cells that have separate haploid nuclei. These hyphae called dikaryotic.

General fungal traits

*    Example of fungal life cycle with dikaryotic hyphae: mushroom

*    Dikaryotic mycelium is major phase

*    Only when mushroom is formed does karyogamy occur, followed by meiosis.

Fungal Phyla

*    3 phyla but 4 groups

*    Phyla separated mainly by how meiospores are formed (how sexual reproduction done)

*    Phylum Zygomycota (zygomycetes or bread molds): Meiospores made by zygosporangium (resistant microscopic structure).

 

Fungal Phyla

*    3 phyla but 4 groups

*    Phyla separated mainly by how meiospores are formed (how sexual reproduction done)

*    Phylum Ascomycota (ascomycetes or sac fungi): Meiospores made in sac-like ascus. Asci (plural) containing in fruiting body called ascoma (plural ascomata).

Fungal Phyla

*    3 phyla but 4 groups

*    Phyla separated mainly by how meiospores are formed (how sexual reproduction done)

*    Phylum Basidiomycota (basidiomycetes or club fungi): Meiospores made on club-like basidium. Basidia (plural) contained in fruiting body called basidioma (plural basidiomata).

Fungal Phyla

*    3 phyla but 4 groups

*    4th group? Fungi that donšt make meiospores (to our knowledge)

*    Reproduce only asexually (by mitospores)

*    Called Imperfect Fungi

*    Not a true phylum but a temporary holding group.