Protist characteristics • Protists are organisms that do not fit into any other kingdom. They can either by uni-celled or simple multicellular. They can be animal-like, plant-like, or fungus-like. • Protists are made up of eukaryotic cells, each containing a nucleus and other organelles.
Protist characteristics • A hypothesis for how eukaryotic cells arose: • From prokaryotes that obtained organelles via endosymbiosis. • Protists are often classified: • By how the resemble fungi, plants, or animals • Most protists are unicellular such as an amoeba. Some of these unicellular protists form colonies in which several cells are joined into a larger body, such as Volvox.
Protist characteristics • A few protists are multicellular, such as Brown algae. They have specialized regions for reproduction, photosynthesis, and attachment to the ocean floor, but lack true tissues and organs.
Protist characteristics • Two ways in which protists obtain energy: • Autotrophy • Heterotrophy
Protist characteristics • Protists move via • Flagella • Cilia • Pseudopodia
Protist characteristics • Protists reproduce: • Asexually either binary or multiple fission • Sexually conjugation
Animal-Like Protists • Phylum Protozoa • Single-celled protists that can move independently without cilia or flagella • Have pseudopodia which are large, rounded cytoplasmic extensions that function both in movement and feeding. They engulf small organisms. • Move by amoeboid movement, which is a form of cytoplasmic streaming. • An example of a Protozo is an Amoeba • Harmful to humans in that some can live in human intestines and attack the lining, and may cause disease
Animal-Like Protists • Phylum Ciliophora • They share one key feature: they have cilia which are: short, hair like cytoplasmic projections that line the cell membrane. • Cilia make it possible for these protists to move. • An example of Ciliophora is Paramecia. • The process in which two Paramecia come together after meiosis to exchange parts of their genetic material is called conjugation.
Plant-like Protists • Algae • Many plant-like protists are known as algae. • Algae are autotrophic protists and have chloroplasts and produce their own carbohydrates by photosynthesis, as plants do. They do not have true roots, stems, or leaves.
Plant and Animal-like Protists • Phylum Euglenophyta • Phylum Euglenophyta contain flagellated unicellular algae called euglenoids, which are both plant-like and animal-like. • How are they like plants? • Autotrophic, contain chlorophyll • Have contractile vacuole and chloroplast • How are they like animals? • Lack a cell wall and are highly motile • If raised in dark, do not form chloroplast and become heterotrophs
Plant and Animal-like Protists • Where do you find Euglena? • In fresh water, especially water polluted by excess nutrients • How do they move? • Long flagellum
Fungus-like Protists Slime mold- can either be: *mobile, amoeba-like feeding *sessile, reproductive spore-bearing form Water mold- composed of branching filaments of cells
Protists and Humans • Environmental roles of protist producers: • Produce oxygen • Form the foundation of food webs • Recycle materials
Protists and Humans • Protists symbiosis: • Corral, fungi, and termites
Protists and Humans • Protists for food: • Seaweeds are eaten directly • Byproducts are used to make cheeses, ice cream, salad dressing, and bakery items.
Protists and Humans • People use: • Alginate is used in cosmetics • Carageenan is used in gelatin capsules • Agar is used to culture microbes
Protists and Humans • What is Giardiasis? • Caused by Giardia lamblia • Reults in diarrhea and cramps
Protists and Humans • What is Cryptosporidiosis? • Caused by Cryptosporidium paruum • Characterized by diarrhea
Protists and Humans • What is Trichomoniasis? • Caused by Trichomona vaginalis • An STD that causes discolored discharge and genital itching.