Transcript PROTISTA
PROTISTA CH.21 Sections 21.1, 21.2, 21.3 What are protists? Protists are eukaryotes that are not members of the plant, animal, or fungi kingdoms. Protists—Ancestors and Descendants The roots of all eukaryotic diversity, from plants to animals, are found among the ancestors of protists. How Protists Move How do protists move in the environment? Changing their cell shape Specialized Carried organelles by wind, water, or other organisms. Amoeboid Movement Cilia and Flagella Protists that move using cilia are known as ciliates, and those that move with flagella are called flagellates. Protist Reproduction How do protists reproduce? Asexually Life = mitosis cycles that combine asexual and sexual forms of reproduction. Cell Division Mitosis: They duplicate their genetic material and then divide into two genetically identical cells. Mitosis enables protists to reproduce rapidly, especially under ideal conditions, but it produces cells that are genetically identical to the parent cell, and thus limits the development of genetic diversity. Conjugation Paramecia and most ciliates reproduce asexually by mitotic cell division. However, under stress, paramecia can remake themselves through conjugation—a process in which two organisms exchange genetic material. After conjugating, the cells then reproduce by mitosis. Sexual Reproduction Many protists have complex sexual life cycles in which they alternate between a diploid and a haploid phase, a process known as alternation of generations. Autotrophic Protists What is the ecological significance of photosynthetic protists? The position of photosynthetic protists at the base of the food chain makes much of the diversity of aquatic life possible. ALGAE! (Al-Gee) Feeding Fish and Whales Photosynthetic protists make up a large portion of phytoplankton (small, free-floating photosynthetic organisms found near the surface of oceans and lakes) Supporting Coral Reefs Coral are animals, fed by algae and other plankton. Providing Shelter The largest known protist is giant kelp, a brown alga that can grow to more than 60 meters in length. Kelp forests provide shelter for many marine species. Kelp is also a source of food Heterotrophic Protists How do heterotrophic protists obtain food? Some engulf and digest their food, while others live by absorbing molecules from the environment. Amoebas Amoebas can capture and digest their food, surrounding a cell or particle and then taking it inside themselves to form a food vacuole. A food vacuole is a small cavity in the cytoplasm that temporarily stores food. Ciliates Paramecium and other ciliates use their cilia to sweep food particles into the gullet, an indentation in one side of the organism. The particles are trapped in the gullet and forced into food vacuoles that form at its base. Mutualists Trichonympha is an example of a mutualistic protist. Trichonympha is a flagellated protist that lives within the digestive system of termites and makes it possible for the insects to digest wood. Parasites and Disease Parasitic protists are responsible for some of the world’s most deadly diseases, including several kinds of debilitating intestinal diseases, Giardia, Amebic dysentery, African sleeping sickness, and malaria. Amoebic dysentery Dysentery: a water-borne disease…caused by a parasite amoebic dysentery caused by contaminated food and drinks, is the most dangerous amoebae species (mostly found in tropical areas). African sleeping sickness Human African trypanosomiasis, also known as sleeping sickness, is parasitic disease. It is caused by protozoan parasites belonging to the genus Trypanosoma. They are transmitted to humans by tsetse fly (Glossina genus) bites which have acquired their infection from human beings or from animals harboring the human pathogen Malaria Mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans FUNGI CHARACTERISTICS CELL WALLS HETEROTROPHIC...Most are “Saprophytes”, decomposers NON-photosynthetic EX: molds, yeast, mushrooms, and other assorted “fungus” Anatomy of a mushroom Hyphae - the vegetative filament. The fungi cell wall is made of chitin, a complex polysaccharide found in insects. This distinguishes fungi from plants, which have a cell wall made of cellulose. MYCELIUM A mat of interwoven hyphae Fungi act as parasites Athletes Foot and Athletes foot treatment Fungus Nail/ Fungal Nails Fungi form a symbiosis A lichen is a composite organism that emerges from algae or cyanobacteria (or both) living among filaments of a fungus in a mutually beneficial (symbiotic) relationship Fungi act as decomposers Gee, they keep me in the dark and feed me..... horse manure!