Biology 1110 Laboratory: Kingdom Protista - The Protozoans (PDF)

BIOLOGY BIOLOGY 1110฀ 1110฀ PRINCIPLES PRINCIPLES OF OF BIOLOGY BIOLOGY Biology 1110 Laboratory Laboratory # 8 Kingdom Protista – The Protozoans Support/Review Materials All of...

BIOLOGY BIOLOGY 1110฀ 1110฀ PRINCIPLES PRINCIPLES OF OF BIOLOGY BIOLOGY Biology 1110 Laboratory Laboratory # 8 Kingdom Protista – The Protozoans Support/Review Materials All of the micrographs in this presentation were photographed in the MnWest Biology laboratory unless otherwise noted. The microscope symbol that you see indicates a change in microscope power. A left mouse click on the microscope most often increases the viewing magnification. Give it a try.  Kingdom Protista฀. ฀ Kingdom Protista consists of unicellular, multicellular, and colonial eukaryotes, that are in many ways, unlike animals, plants, or fungi (the other eukaryotes). ฀ All protists require some sort of aquatic environment. Protists are found in fresh water and marine environments. ฀ Ecological significance: The protists can exist in great numbers in aquatic systems and are an important part of the plankton. The plankton forms the base of aquatic food chains. ฀ Some protozoans are important decomposers in living systems.  Kingdom Protista฀ The plant-like protists are the algae. The algae are autotrophic (specifically photosynthetic) and range from single-celled species and others common in local waters, to the giant multicellular algae of the sea. In this presentation we are studying the animal-like protists, known as the protozoans. Like the animals, the protozoans are heterotrophic. Some protozoans, such as the amoebas and paramecia are known to us, if only in name. The majority of protozoans are free-living, contributing to the living system, and causing no harm to other living things. Some protozoans, however, are disease-causing to humans and Some Human Diseases Caused by Protozoans Disease Causative Agent Motion by Transmission Amoebiasis Entamoeba histolytica Pseudopodia water, food Giardiasis Giardia lamblia Flagella water, contact Trichomoniasis Trichomonas vaginalis Flagella sexual, contact African Sleeping Sickness Trypanosoma brucei Flagella Tsetse fly Balantidiasis Balantidium coli Cilia Food, water Toxoplasmosis Toxoplasma gondii NA Domestic cats, food Malaria Plasmodium sp. NA Mosquito (Anopheles)  Protozoan Classification Kingdom Protista Subkingdom Protozoa Phylum Sarcomastigophora Ciliophora Subphylum Mastigophora Sarcodina ------------- Genus Euglena Amoeba Paramecium species Euglena sp. Amoeba proteus Paramecium caudatum  Representative Protozoans ฀ Although it is changing, traditional protozoans classification has been according to mode of locomotion. In this exercise we will look at a protozoan that moves via ameoboid motion, a flagellated protozoan and a ciliated protozoan. Often, the common name for protozoans is the name of the Genus. Check it out. Common names we use will be amoeba, euglena, and paramecia. ฀ Micrographs of living and stained specimens will be utilized in our study.  Representative Protozoans Euglena sp. Amoeba proteus Paramecium caudatum  Amoeba In the listing and on the diagram you will find the structures/organelles we will be observing in the micrographs of stained and living amoebas. Clicking the forward button will take you to the appropriate micrograph. Clicking the return button will bring you back to the listing. Organelles/structures to identify. Nucleus Plasmalemma (cell membrane) Ectoplasm Endoplasm Pseudopodia Food vacuole Contractile vacuole  The Amoeba - Nucleus Amoeba proteus is the particular species of study for preserved, stained specimens and most living specimens. The common name is amoeba. As is the case in all eukaryotic cells, the nucleus contains most of the cell’s DNA and is the control center for the cell. Living Amoeba proteus Stained Amoeba proteus Nucleus  The Amoeba – Plamalemma, Ectoplasm, and Endoplasm The plasmalemma is the outer limiting cell membrane. The ectoplasm is a layer of relatively clear cytoplasm immediately inside the plasmalemma. The ectoplasm is important in movement and feeding. The abundant endoplasm is the more fluid, granular appearing cytoplasm. The endoplasm contains the majority of the cell organelles. Living Amoeba proteus Stained Amoeba proteus Plasmalemma Ectoplasm Endoplasm  The Amoeba - Pseudopodia Pseudopodia are the locomotor organelles for amoebas. The term pseudopodium translates to mean false foot. As the protoplasm flows, pseudopodia are formed and the amoeba moves in that direction. This locomotion is called amoeboid motion. Living Amoeba proteus Stained Amoeba proteus Pseudopodia  The Amoeba – Food Vacuoles Amoebas extend pseudopodia around their food and engulf the material through the process of phagocytosis. This process results in membranous food vacuoles being released to the inside of the cell. Living Amoeba proteus Stained Amoeba proteus Food Vacuoles Food Vacuoles The Amoeba - Contractile vacuoles Because protozoans live in fresh water, water continuously enters the cell. To prevent the protozoan from swelling and bursting , contractile vacuoles collect water and pump it to the outside. Living Amoeba proteus Stained Amoeba proteus Contractile vacuole Contractile vacuole  Euglena sp. In the listing and on the diagram you will find the structures/organelles we will be observing in the micrographs of stained and living amoebas. Clicking the forward button will take you to the appropriate micrograph. Clicking the return button will bring you back to the listing. Organelles/structures to identify Flagellum Chloroplasts Nucleus Stigma Cytostome Contractile vacuole  Euglena sp. - Flagellum The locomotor organelle for the euglenoids is a single whip- like flagellum. This group of protozoans are referred to as the flagellates. Living Euglenoid Preserved Euglena sp. Flagellum Flagellum  Euglena sp. - Chloroplasts Euglenoids, like most animals and other protozoans, move about their environment and consume food. In addition to this heterotrophic lifestyle, euglenoids contain numerous chloroplasts. Like green plants euglenoids are capable of photosynthesis. They are heterotrophic and autotrophic. The green photosynthetic pigment chlorophyll gives living Euglena a green coloration. Living Euglenoid Preserved Euglena sp. Chloroplasts Chloroplasts Euglena sp. - Nucleus The Nucleus is the control center of the cell. It contains the great majority of the cell’s DNA. Nuclear material stains deeply making it easily identifiable. Preserved Euglena sp. nucleus  Euglena sp. - Stigma Most euglenoids are quite small and as a consequence we use the diagram to assist in our learning. The stigma is a light sensitive structure (primitive eye). This structure proves useful for a mobile, photosynthetic organism. Living Euglenoid Stigma  Euglena sp. – cytostome, contractile vacuoles, and pellicle The cytostome is a an opening used in feeding (primitive mouth). Contractile vacuoles pump water to the outside as was seen in our study of Amoebas. Living Euglenoid Cytostome location Next protozoan Contractile vacuole The pellicle is a membrane outside the cell membrane that provide support and flexibility.  Paramecium caudatum Like other ciliates, paramecia move very efficiently by using the coordinated action of cilia. Paramecium caudatum is a fairly large protozoan and we will study micrographs of both living and preserved specimens. ฀ Organelles to be identified Cilia Macronucleus & micronucleus Contractile vacuole Oral groove Food vacuole Peliicle, ectoplasm, endoplasm  Paramecium caudatum - Cilia Often Paramecium caudatum is the ciliate of choice for study. As you can see in the micrographs below, the cell is covered with many cilia. The coordinated action of the cilia propel the organism and assist in food consumption. Preserved Living Paramecium Paramecium Cilia Cilia  Paramecium caudatum – Macronucleus & Micronucleus One way in which ciliates differ from other protozoans is in having two kinds of nuclei. The large macronucleus is involved in regulating growth and metabolism. The small micronucleus is involved in reproduction and genetic recombination. Preserved Paramecium Macronucleus Micronucleus Paramecium caudatum – Contractile Vacuoles Water continually moves into single-celled protozoans. In order to maintain water balance, excess water must be collected and pumped to the exterior. Contractile vacuoles perform this function. Living Paramecium Preserved Paramecium Contractile vacuoles Contractile vacuoles Lets take a closer look  Paramecium caudatum - Contractile Vacuoles In this high power micrograph, Contractile you can clearly see a contractile vacuole vacuole and the radiating canals that collect water and deliver it to the pumping structure. The contractile vacuoles help maintain the osmotic balance between the inside of the cell and Radiating canals the cell’s environment. Living Paramecium Paramecium caudatum – Oral Groove and Food Vacuoles The cilia within the oral groove sweep food material towards the cytostome and then into the cytopharynx. Material brought into the cell is packaged in a membranous food vacuole. Living Paramecia Oral Groove Lets look on high power Paramecium caudatum – Oral Groove and Food Vacuoles The material is Living Paramecium Forming Food moved into the cell Cytopharynx vacuole via the cytostome. At the end of the cytopharynx food vacuoles are formed. Other food vacuoles Anterior end can be observed close by.  Paramecium caudatum – Pellicle, ectoplasm, and endoplasm. As you watch living Paramecia, Living Paramecium you see they have a definite, yet flexible shape. This due to the membranous pellicle (not Endoplasm visualized). Like in the Amoeba, there is a thin, comparatively clear ectoplasm immediately inside the plasmalemma (cell membrane). Ectoplasm The more abundant granular endoplasm contains most of the cell’s organelles.  Paramecium – Fission Fission is a form of asexual (one parent) reproduction, where a single “mother” cell gives rise to two “daughter” cells. It is a continuous process, but often we speak in terms of stages. Preserved Paramecium In the early stages of fission the cell thickens, the micronucleus divides mitotically ( not observed), and the macronucleus elongates as it gets ready to divide. Note the two cells pointed out in the micrograph.  Paramecium – Fission As the process continues into and through the middle stages, the macronucleus divides. In latter stages cell division continues and then completes. When the two “daughter “ cells separate, one must regenerate a new anterior end, the other must regenerate a new posterior end. All micrographs are preserved, stained Paramecia Fission complete  Paramecium – Conjugation Most ciliates are capable of Preserved Paramecium conducting a sexual process called conjugation. This is not a reproductive process in that it starts with two and ends with two. The two conjugating paramecia exchange genetic material so that they are different genetically when the process is complete.  Paramecium – Conjugation Preserved Paramecium Through the process of conjugation, genetic diversity is added to the ciliate population. Conjugation is one form of genetic recombination. The diversity that results is particularly important to the asexually reproducing ciliates.  n d e E Th Try it again