EUKARYA

KINGDOM PROTISTA I

Origin of Eukaryote: The Origin of Eukaryote: The Endosymbiotic Theory (1960)Endosymbiotic Theory (1960)

Pages 229, 307

Prove: EndosymbioticProve: Endosymbiotic

Plastid and mitochondria have their own DNA & ribosome that are 70s not 80s

They divide in a way similar to Prokaryotes, lack microtubules

Their DNA is circular, naked Their ribosome are sensitive to the same

antibiotics that interfere with prokaryotes ribosome Evidence of symbiotic relationship between

bacteria & protists, marine invertebrates, algae & protozoan (Fig. 12-11)

Mitochondria arose first (common to all Eukaryotes), from purple nonsulfur bacteria!

Meiosis & Life cyclesMeiosis & Life cycles

For meiosis see page 236 In eukaryote a diploid stage undergo meiosis to

produce a haploid stage These two stages alternate in three patterns

Gametic meiosis: most animals & some protists Sporic meiosis (alternation of generations: plants &

many algae*Zygotic meiosis: Fungi & some algae*

Gametic MeiosisGametic Meiosis

FertilizationGametes- + - +

Meiosis (spermatogenesis)

Diploid individual

Zygote

This cell undergo meiosis

- gamete+ Gamete

e.g. Human & some protists

Sporic MeiosisSporic Meiosis

MeiosisFertilizationspores

- + - +

Sporophyte(Diploid individual)

Zygote

- Gamete+ Gamete

Gametophyte(Haploid individuls)

This cell undergo meiosis

e.g. Plants

Reproductive CyclesReproductive CyclesAnimals and PlantsAnimals and Plants

Adult ♀

Adult ♂

Egg

Zygote

Embryo

2n

1n

Meiosis

Fertilization

Sperm

Spore GametophyteSporophyte

Zygotic MeiosisZygotic Meiosis

MeiosisFertilization

Haploid cells- + - +

Zygote

- Gamete+ Gamete

Haploid individuals

e.g. Fungi

Classification of the ProtistsClassification of the Protists

Protista is established to hold problematic species Each algal group must have its own evolutionary line Organisms of uncertain origin are paced in the

Protista Protista includes:

Plant-like organisms but gametes & zygotes not protected

Fungi-like organisms but have flagella & lack chitin in cell wall

Animal-like organisms but no embryonic development

Ecology of Aquatic AlgaeEcology of Aquatic Algae

Marine algae & cyanobacteria form phytoplankton Importance

Important in carbon cycle (absorb ½ CO2 produced by human activities)

Transform CO2 into (CH2O)n & CaCO3

Cause algal blooms (red & brown tides)Increase sulfur oxides in our atmosphere

Lake Neatahwanta, Fulton, NY

Euglenoids: Phylum Euglenoids: Phylum EuglenophytaEuglenophyta

e.g. Euglena Like green algae, have chl(a), (b) & carotenoids

suggesting a symbiotic relationship Only 1/3 of the phylum has chloroplast, the rest

are heterotrophic Euglenoids occur in freshwater rich in organic

matter

EuglenaEuglena

Reproduce by mitosis & lengthwise

Plasmodial Slime Molds: Plasmodial Slime Molds: Phylum MyxomycotaPhylum Myxomycota

The name mold “thought to have a relation with fungi” Seems to have no close relation to other organisms Plasmodium: amoeboid body with no cell wall Phagocyte: heterotrophic

Sclerotium

Plasmogamy

Oomycetes: Phylum OomycotaOomycetes: Phylum Oomycota

They are not Fungi becauseCell wall has cellulose-like polymers Chromosomes not highly condensed as in fungispores are flagellated

They are saprobic, few are parasitic Pathogens of Coca, pineapple, tomatoes, rubber,

papayas, onions, citrus e.g. the genus Plasmopara e.g. Phytophthora infestans (Late blight of potato)

Downy mildew in Grapes: Downy mildew in Grapes: Plasmopara viticolaPlasmopara viticola

Downy mildew in grapes, threaten the entire wine production in France (introduces from the States 1870)

http://www.inra.fr/Internet/Produits/HYP3/pathogene/3plavit.htm#det

Late Blight of PotatoLate Blight of Potato (Phytophthora infestans)(Phytophthora infestans)

Responsible for the great famine of 1846-47 in Ireland

Dinoflagellates: Phylum DinophytaDinoflagellates: Phylum Dinophyta

Mostly unicellular & biflagellate Have chl. a, c, & carotenoid Important part of marine phytoplankton Many produce toxins (red & brown tides)

DinoflagellatesDinoflagellates

Unique: flagella move within 2 groves

Ceratium

http://www.microscopy-uk.org.uk/mag/artsep01/dinof2.html

Red tide in Texas Bay, Gymnodinium breve

Diatoms: Phylum BacillariophytaDiatoms: Phylum Bacillariophyta

Very important component of phytoplankton Occur in huge # 30-50 m/1 cm of a submerged

rock (1/4 of total carbon fixed) They lack flagella & have unique shells

* Pennate diatoms: bilaterally symmetrical*

* Centric diatoms: radially symmetrical*

- Centric float better therefore more abundant

Pennate DiatomsPennate Diatoms

Diatoms: often compared to a shoe box and its lid (frustules)

Cell wall has an outer layer of silica (glass)

3 µ

m

Lower valve (the box) Upper valve (lid)

Chrysophytes: Phylum Chrysophytes: Phylum ChrysophytaChrysophyta

Have chl(a) & (c) masked with a golden-brown fucoxanthin (=chrysophyte)*

Mostly unicellular or colonial; flagellated Found in fresh & salt water all over world Reproduction is asexually by zoospores

Synura sp.Synura sp.

http://www.spea.indiana.edu/e455-jones/synura.jpg