Domain Eukarya Kingdom(s?): Protists

Themes in the Evolution of Protists n Larger Cell Size Larger cells make possible the evolution of diverse structures and functions. Compartmentalization increases the available surface area in the interior of cells, easing food & waste transport in & out of the cell. Paramecium: a unicellular cilliate

Themes in the Evolution of Protists n Locomotion Pseudopods Protists can be motile by means of cilia or flagella. 2 single microtubules 9 paired microtubules Flagella Cilia The structure of eukaryotic flagella and cilia is different than prokaryotic flagella

Themes in the Evolution of Protists n Multicellularity Volvocales spp. range from unicellular to colonial to multicellular. Chlamydomonas Gonium PandorinaVolvox

Some protists are clearly multicellular This green alga, called Coleochaete orbicularis, is multicellular. Its cells are packed tightly together and are differentiated in form and function.

Themes in the Evolution of Protists n Meiosis and sexual reproduction Meiosis makes eukaryotic sexual reproduction possible.

Meiosis A1A1 A2A2 A1A1 A2A2 Parental genotype Gametes A1A1 or A2A2 Fertilization Offspring genotypes A1A1 A2A2 A1A1A1A1 A2A2A2A2 Sexual reproduction produces genetic variability

Chlamydomonas (n)(n) ASEXUAL REPRODUCTION SEXUAL REPRODUCTION (n)(n) (n)(n) (n)(n) (n)(n) (2n) Zygote Gametes Mature cell SYNGAMY MEIOSIS (n)(n) Haploid Diploid Some protists may alternate between sexual and asexual reproduction

Giardia lamblia, a diplomonad Giardiasis is a diarrheal illness sometimes known as “Traveler’s Disease”

Group 2: Euglenozoa n Typically unicellular n Characteristic type of flagella (1-2 flagella) n Autotrophic, heterotrophic, or mixotrophic Euglena

Group 2: Euglenozoa- Others n Trypanosomes- Parasitic Trypanosoma brucei- African Sleeping Sickness Carried by Tsetse flies Trypanosoma cruzii- Chagas disease South America Leishmania spp. Worldwide parasites Transmitted by sandflies

Group 3:Aveolata n Dinoflagellates n Primary producers in coastal areas n Armored cellulose walls n Two whip-like flagella Gonyaulax – red tide

Group 3:Aveolata n Apicomplexans n All obligate Parasites Plasmodium--> malaria n Mass of organelles at one end (penetrate the host) n Spore-forming

Group 3:Aveolata n Ciliates n Cilia- short hair-like flagella used for feeding and moving n Oral groove n Multi-nucleate n Reproduce by fission and conjugation Paramecium Stentor

Group 4:Stramenopila n Oomycotes (water molds) n Fungi-like heterotrophs Most live in fresh water or moist soil where they are important decomposers of plant detritus Downy mildew Potato Blight and the Irish Potato famine

Group 4:Stramenopila n Diatoms n Glass cell walls Major component of marine plankton n Major contributor to marine photosynthesis n Sediment to form diatomaceous earth

Algae: Plant-like Protists n Algae are AUTOTROPHIC Protists- they perform PHOTOSYNTHESIS. n Often called “seaweeds”= brown, red, green algae Red: chlorophyll a and phycobilins Brown: chlorophyll a and chlorophyll c Green: chlorophyll a and chlorophyll b

Algae: Plant-like Protists n Algae are Different from Plants because they LACK Tissue Differentiation and have No True Roots, Leaves or Stems.

Group 5:Rhodophyta n Red Algae n No flagellated stages n Color from phycoerythrin n Often used to make cosmetics, gelatin capsules, agar

Group 6:Chlorophyta n Green Algae n Not monophyletic n Closely related to plants n common ancestor of green algae and plants--> chloroplasts through endosymbiosis of cyanobacteria n mostly freshwater n Unicellular, colonial, multicellular

Group 8:???? n Hodge-podge of organisms with unknown phylogeny n Use pseudopods for moving and feeding n Rhizopods (Amoeba) n Actinopods n Foraminifera Phagocytosis in Amoeba

Amoeba have complex life cycles