Characteristics of Protists Are unicellular or simple multicellular Eukaryotic Not plants, fungi or animals Many are autotrophs and others are heterotrophs Use flagella, cilia or pseudopodia for locomotion Reproduce asexually Reproduce sexually by conjugation

Animal-like Protists Sometimes called protozoa Amoeba Have pseudopodia that are large, rounded cytoplasmic extensions that function both in movement and feeding Moves by amoeboid movement-cytoplasmic streaming Prey on smaller protists and bacteria Live freely , some live in human intestines and cause disease (ulcers)

Amoeba

Animal-like cont… Paramecium Move by cilia Found in ponds and slow moving streams that contain plants and decaying organic matter Asexual-binary fission Sexual-conjugation (exchange genetic material with the micronucleus)

Animal like protist

Animal-like…. Sporozoans Animal parasites (complex life cycle and usually need 2 host) Plasmodium causes malaria and needs both mosquitoes and humans Absorb nutrients and destroy host cells May have killed more people than any other group of pathogens

Malaria life cycle Begins life cycle in mosquito and transfers to a human Attacks healthy red Blood cells

Animal-like… Trypanosomes live in the blood of fish, amphibians, reptiles, birds and mammals and are carried from host to host by blood sucking insects Tsetse fly which lives only in Africa transmits these parasites causing sleeping sickness (increasing fever, lethargy, mental deterioration and coma)

Plantlike Protists Most are known as algae Have chloroplasts and produce their own carbohydrates by photosynthesis but have no true roots, stems or leaves. Examples: green algae, brown algae, red algae, diatoms, dinoflagellates, golden algae and euglenoids.

Multicellular algae

Euglena

Dinoflagellates – Cause red tide

Plantlike… Euglenoids Both plantlike and animal-like Most are autotrophic but lack a cell wall Highly motile Live in fresh water, but a few occupy moist environments such as soil or the digestive tracts of certain animals

Funguslike protists (Slime Mold) Live as individual haploid cells that move about like amoebas Move as an independent organism, creeping over the ground or swimming in fresh water and ingesting food but when short on food, will cause them to gather together by 1000’s Produce fruiting bodies that resemble those of fungi

Slime mold

Funguslike (water molds) Some are parasitic with fish Similar means of obtaining nutrients, cell walls made of the same type of material, filamentous bodies and similar enzymes and biochemical pathways Some biologists hypothesize that chytrids (water mold) are a link between protists and fungi

Water mold on a potato

Protists and Humans Produce larger amounts of oxygen, form the foundation of food webs, recycle materials and play a role in several symbiotic relationships Algal blooms can lead to the depletion of oxygen in water. Red tides produce harmful toxins

Protists and humans Can help scientists understand the movement of leukocytes (White blood cells), provide food and provide important byproducts, such as alginate and agar Parasitic protists cause malaria, giardiasis (diarrhea, intestinal cramps), cryptosporidiosis (intestinal cysts), trichomoniasis (STD)