What Are Protists?

• Kingdom Protista

• “odds and ends”

• Eukaryotic organisms

• Heterotroph, autotroph, or decomposer

• Several important characteristics: – membrane-bound organelles– complex cilia and flagella– sexual reproduction with gametes– Multi – cellularity

Reproduction

• Asexually by binary fission, budding, and fragmentation

• Sexually by fusion of gametes

Sexual Reproduction• Occurs as a response to environmental stress• Zygospore

– Adaptation that allows the zygote to survive freezing, drying out, and sun exposure

• Multicellular protists can reproduce both sexually and asexually via alternation of generations. – consists of multi - cellular haploid and multi - cellular

diploid phases.

Classifying Protists

• How they they obtain nutrition

– Photosynthesis

– Breakdown organic material

– Capture and eat other protists

• Ecological role

Animal – Like Protists

• Protozoa “first animals”

• Ingest other organisms to obtain energy

• Unicellular, most can move, and most reproduce asexually by binary fission

Amoeboid Protists

• Move by using extensions of their cells called pseudopodia

– Pseudopodia are also used to surround and engulf food particles

• Live in fresh water, in salt water, and in soil

• Free-living, but some are parasites

Ciliates

• Some of the most complex single - celled organisms

• Most or all of the body is covered by short, hair - like structures called cilia

• Move and hunt for food by beating their cilia

Flagellates

• Protists that have whip-like structures called flagella.

• Some flagellates also have cilia or form pseudopodia.

• Can be free-living or parasitic

Sporozoans

• Animal-like protists that form spore – like cells when they reproduce

• They lack flagella, cilia, and pseudopodia and do not move.

• All sporozoans are parasitic and cause diseases. (Malaria)

Plant – like Protists• Include the organisms known as phytoplankton

and algae.

• Obtain energy through photosynthesis

• Vary in the types of pigments used in photosynthesis and the kinds of molecules used to store energy

• Diatoms, Dinoflagellates, algae

Diatoms

• Photosynthetic, unicellular protists with unique double shells

• Their shells are made of silica or calcium carbonate and have distinct patterns.

Dinoflagellates

• Unicellular protists that typically have two flagella.

• Most are photosynthetic, but some are heterotrophic

• Most have protective coats that contain silica.

Euglenoids

• Freshwater protists that have one or two flagella.

• Many are photosynthetic, heterotrophic, or both.

• Some have an eyespot that helps direct them toward light.

Red Algae

• Most are multicellular and are usually found in warm ocean waters.

• The pigments in red algae absorb blue light that penetrates deep into water.

• Red algae grow at greater depths than other algae.

• Some have calcium carbonate in their cell walls.

– These coralline algae play an important role in the formation of coral reefs.

Brown Algae

• Multicellular protists that are found in cool ocean environments.

• The largest brown algae are kelp that can reach 60 m (197 ft) in length.

• The body of a kelp has is made up of a holdfast, a stipe, and blades

Green Algae

• Very diverse group of protist that form a major part of marine plankton.

• Some inhabit damp soil and resemble plants.

• Some are symbiotic within the cells of other organisms.

• Use chlorophyll for photosynthesis, starch to store energy, and their cell walls contain cellulose.

Fungus – like Protists

• Absorb nutrients from their environment and reproduce by releasing spores.

• Slime Molds

• Water Molds and Downy Mildews

Protists and Humans• Dysentery

– Contaminated water– Giardia, amebiasis

• Toxoplasmosis– Litter boxes and uncooked meat– Flu – like symptoms

• Trichomoniasis– Very common S.T.I

• Cryptosporidiosis– Dysentery from uncooked meat and

contaminated water

• Chagas disease– Kissing bug feces– Few to no symptoms then can become chronic

with heart failure, swollen esophagus and large intestine

Protists and the Environment• Oxygen production and nutrient recycling

– Produce at least half of the Earth’s oxygen

• Food webs– Primary producers

• Algal blooms– Red tide and eutrophication

• Protists symbiosis– Coral, lichen, ungulate digestion