Protists

Eukaryotes w/o tissue level of organization as in animals, plants, and fungi

Generalizations

Most unicellular

Organelles that are similar to eukaryote animals

None have embryonic tissue layers as in animals

Classification of Protista:

Excavata Diplomonadida = Giardia Kinetoplastida = trypanosomes Euglenida = Euglena

Alveolata & Chromista Ciliophora = ciliates Apicomplexa = gregarines, coccidians Dinoflagellata = flagellates Opalinida = Opalina

Classification of Protista:

Rhizaria Rhizopoda = amoebas Actinopoda = radiolarians

Amoebozoa Lobosea = amoebas

Opisthokonta Chlorophyta = Volvox

Support and Locomotion

Plasma membrane Many have thickening = pellicle Or a test

Pseudopodia, cilia, flagella

Nutrition

Autotrophs = ? Heterotrophs = ? Or both

Saprobic = take in dissolved stuff Holozoic = solid foods (food vacuole)

Reproduction

Asexual and sexual

Complex = parasites

Binary fission

Budding

Yeast

Sexual repro

Production of gametes and then fusion = syngamy

Isogamy = same size gametes Anisogamy = one larger

Or conjugation

Phylum Euglenida

Mostly freshwater, few marine, brackish

Usually in habitat w/decaying organic matter

Support

Pellicle = protein under cell membrane Stripes are seams in protein strips Flexible

Locomotion by flagella

Two flagella, one usually shorter

Nutrition

1/3 have chloroplasts Positive phototaxis Photoreceptor near base of anterior flagellum

2/3 euglenids w/o chloroplasts = heterotrophs = phagocytosis Others can lose chloroplasts and switch

Few parasitic forms

Saprotrophic = take in dissolved nutrients

Euglenid reproduction

Asexual by longitudinal cell division

Euglenida examples you need to know:

Euglena

Perinema

Other Euglenida?

Phacus

+ Astasia

Other Euglenida?

Phylum Kinetoplastida

Trypanosomes, etc. ~ 600 species described Some free-living

Trypanosomes strictly parasitic Digestive tracts of invert’s, phloem of plants,

blood of vert’s

Trypanosoma cruzi life cycle: Chagas’

Reduviid = assasin bug

Other parasitic forms Leishmania: transmitted by sandflies Causes skin and mucous membrane

infections in humans

T. gambiense, others = sleeping sickness Tse-tse fly is intermediate host Tryps get into blood, then lymphatics and CS

fluid

Support, locomotion

Pellicle, glycoprotein protects outside

Flagella: single, against side of cell

nucleus

kinetoplastkinetosome

Nutrition

Mostly unknown in parasitic forms

Free-living spp. are heterotrophic; capture bacteria with flagellum

Reproduction

Asexual by longitudinal binary fission, budding

Complex life cycles

Kinetoplastida you need to know!

Leishmania

Infection occurs when infected sandfly regurgitates infective promastigotes into the blood while feeding.

The promastigotes are phagocytized by macrophages and transform into amastigotes.

The amastigotes multiply by binary fission in the macrophages.

The life cycle is continued when a sandfly feeds on an infected person and ingests the amastigotes in the macrophages.

Leishmania

Amastigotes in blood

Amastigotes in liver cells

Leishmania

Trypanosoma lewisi

Trypomastigote in vert. blood (infective form)

Phylum Ciliophora ~ 12,000 described species

Common in benthic, planktonic communities

Freshwater, marine, brackish

Most are single celled

Mutualistic symbionts

E.g., in goats, sheep Feed on plant material

Some are parasites in fish gut, one in human gut

Support, locomotion

Alveolar membrane system Underlying fibrous layer = epiplasm

Cilia in rows; used in taxonomy More flexible for locomotion than flagella Beat in cone

Ciliophora you need to know: Didinium

Ciliophora Paramecium, Vorticella

Ciliophora Euplotes

Ciliophora Spirostomum