- Slides: 22
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 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