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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