Unit 2 - Kingdom Protista

KEY CONCEPTS Protists are a diverse group of eukaryotic organisms, most of which are microscopic

What Are Protists? “Dumping ground” kingdom Eukaryotic Heterotrophic and/or autotrophic Single or multicellular Ancestors to animals, plants, fungi

All Life Functions in Just One Cell Have food and waste VACUOLES for storing and digesting food & wastes Many are capable of MOVEMENT RESPOND to environment – some have light sensitive eyespot Amoeba Paramecium

All Life Functions in Just One Cell Maintain HOMEOSTASIS Contractile Vacuoles pump out excess water Form Protective Cysts when food or water is scarce (dormant stage with hard covering) Contractile Vacuole Pumping

Reproduction Reproduction Asexual: fission Binary Fission - divides into 2 identical individuals (clones) Rapid reproductive rate

Some Reproduce SEXUALLY Sexual: produce gametes (specialized sex cells) Advantage: new combinations of genes from both parents

Protist Characteristics Eukaryotic Unicellular Some may live in colonies May be Autotrophic or Heterotrophic or Both Some are motile Appeared about 1.5 BYA

Classified into Three Main Groups Animal-like… heterotrophs capable of locomotion Plant-like… photosynthetic autotrophs Fungus-like… decomposers that reproduce by spores Some protists may exhibit both animal-like & plant-like characteristics

Classification of Selected Medically Important Protozoa Four groups Mastigophora - flagellates Sarcodina - amoebae Ciliophora - ciliates Apicomplexa – aka Sporozoans Based on: Method of motility Mode of reproduction Stages in the lifecycle

Animal-like Protists classified by method of movement

Phylum Rhizopoda: ex. Amoeba

The Amoeba uses pseudopodia for locomotion.

Amoeba surround and engulf their food… the process is called phagocytosis. An Amoeba eating a Paramecium.

Amoeba

Phylum Ciliophora all use cilia for movement have many specialized structures, including mouths, anal pores, contractile vacuoles, and two nuclei (a large macronucleus and small micronuclei) Ex. – Paramecium and Stentor

Phylum Ciliophora: ex. Paramecium

Ciliates

Phylum Sporozoa are parasites have no means of locomotion form spores that are dispersed by one or more hosts ex. Plasmodium, which causes malaria

Portions of the Life Cycle of Plasmodium vivax It’s Vector: Anopheles Mosquito Red Blood Cells

Malaria

Giardiasis Fecal-oral route of infection recreational water, water, fomites, contaminated uncooked food Symptoms normally begin 1 to 2 weeks (average 7 days) after becoming infected. Symptoms Diarrhea Stomach or abdominal cramps Upset stomach or nausea May lead to weight loss and dehydration Symptoms of giardiasis may last 2 to 6 weeks.

Plant-like Protists are classified by COLOR

Plant Like Protista Few cause disease Many are microscopic Importance of Protists Autotrophic protists = algae Photosynthetic algae are the most important primary producers of the world’s freshwater and marine ecosystems Many are microscopic Some are huge: kelp Few cause disease Toxic blooms of dinoflagellates cause Red tides shellfish poisoning

Diatoms Giant Kelp

Photosynthetic Producers Energy Photosynthesis 6 CO2 + 6H2O 6 C6H12O6 Respiration Energy

Phylum Euglenophyta have one to three flagella at their leading (apical) end have an eyespot that permits them to swim toward light can become heterotrophic when there is no light

Euglena (arrow indicates anterior end) The Euglena uses a flagella as a means of locomotion.

Evolutionary Considerations One group of flagellates, the choanoflagellates, is thought to have given rise to the simplest animals, the sponges.