Copyright Pearson Prentice Hall Biology Biology Copyright Pearson Prentice Hall

20-2 Animal-like Protists: Protozoans Photo Credit: Andrew Syred/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Classification of Protists One way protists can be classified is by how they obtain nutrition (3 groups): Heterotrophs are called animal-like protists. Photosynthesizers are called plantlike protists. Decomposers and parasites (external digestion) are called funguslike protists. This classification does not reflect the evolutionary history of these organisms ! Copyright Pearson Prentice Hall

Animal-like Protists: Protozoans Collectively referred of as Zooplankton Copyright Pearson Prentice Hall

20-2 Animal-like Protists: Animal-like protists are classified by their means of movement. There are four phyla of animal-like protists: zooflagellates sarcodines ciliates sporozoans Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Zooflagellates (Zoomastigina) Animal-like protists that swim using flagella are called zooflagellates. Motiles Most zooflagellates are solitary cells. Some form colonies of cells. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Feeding Generally able to absorb food through their cell membranes. Many live in lakes and streams, where they absorb nutrients from decaying organic material. Others live within the bodies of other organisms, taking advantage of the food that the larger organism provides. Ex: Giardia Trichomonas Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Reproduction Asexual reproduction Binary fission: Mitosis followed by cytokinesis results in two cells that are genetically identical Sexual reproduction Gamete cells are produced by meiosis. When gametes from two organisms fuse, an organism with a new combination of genetic information is formed. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates The chanoflagellate, a zooflagellate, is at the origin of the choanocytes in sponges, early animal Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Sarcodines Sarcodines are animal-like protists that have pseudopods (pseudo = false, pod = foot). Pseudopods are temporary cytoplasmic projections used for feeding or movement. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Amoebas Amoebas are flexible, active cells with thick pseudopods that extend out of the central mass of the cell. Cytoplasm streams into the pseudopod, and the rest of the cell follows. This type of locomotion is known as amoeboid movement. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Amoeba Feeding Heterotrophic Endocytosis, food vacuoles Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Video Amoeba eats two paramecia (ciliate protist) for lunch (43sec): https://www.youtube.com/watch?v=pvOz4V699gk Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Amoeba Reproduction Asexual reproduction Mitosis and cytokinesis Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Other Sarcodines Foraminiferans Radiolarians Heliozoans Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sarcodines Other Sarcodines Foraminifers Radiolarians Heliozoans These groups of protists produce external shells, made out of silica or calcium carbonate, to help support their unusual shapes. As these protists die the outer shells accumulate on ocean floors. The white cliffs of Dover, England, are huge deposits of calcium carbonate skeletons. Thanks to their external skeleton, these protists are found as fossils. Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ciliates Ciliates Ciliates use cilia for feeding and movement. Cilia are short hair-like projections that propel a cell. The internal structure of cilia is identical to flagella. Ciliates are free living – not parasites or symbionts Found in fresh or sea water Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ciliates Ex. : Paramecia  One type of ciliate is a paramecium. In a paramecium, the cilia are grouped into rows and bundles, and beat in a regular pattern. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ciliates Structures of a Paramecium (~350µm long) Ciliates use hairlike projections called cilia for feeding and movement. Ciliates, including this paramecium, are covered with short, hairlike cilia that propel them through the water. Cilia also line the organism’s gullet and move its food—usually bacteria—to the organism’s interior. There, the food particles are engulfed, forming food vacuoles. The contractile vacuoles collect and remove excess water, thereby helping to achieve homeostasis, a stable internal environment. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ciliates Structures of a Paramecium (~350µm long) Trichocysts: - Used for defense - Spiny projections contained in the cell membrane of the organisms - When the paramecium is in danger, the trichocysts discharge and the spines cover the outside of the paramecium. Ciliates use hairlike projections called cilia for feeding and movement. Ciliates, including this paramecium, are covered with short, hairlike cilia that propel them through the water. Cilia also line the organism’s gullet and move its food—usually bacteria—to the organism’s interior. There, the food particles are engulfed, forming food vacuoles. The contractile vacuoles collect and remove excess water, thereby helping to achieve homeostasis, a stable internal environment. trichocyst spines released Copyright Pearson Prentice Hall

Feeding and food Excretion Zooflagellates Feeding and food Excretion Food is caught by cilia, brought to the gullet, engulfed in food vacuoles to the cytoplasm, digested by lysosomes, released by anal pore Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Water Excretion Fresh water protists collect excess water because water passively moves from outside to inside the cell. This passive movement is called osmosis Contractile vacuoles pump the excess water to outside the cell. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Water Excretion Video on contractile vacuole of paramecium (20sec): https://www.youtube.com/watch?v=iG6Dd3COug4&feature=related Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Reproduction Asexual reproduction - Binary fission (mitosis): normal form of reproduction Sexual reproduction: Under severe conditions – survival is at stake - Conjugation (p.502) - Exchange of DNA between two cells, leads to genetic variability and greater adaptability to environment. - Technically, conjugation is not reproduction as the process does not results in two new cells. But it is a sexual process. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Zooflagellates Conjugation (p502) 1. Two paramecia attach themselves to each other. 2. Meiosis of their diploid micronuclei produces 4 haploid micronuclei but 3 disintegrate. 3. The remaining micronucleus in each cell divides mitotically, forming a pair of identical micronuclei. 4. The two cells exchange one micronucleus from each pair. 5. The macronucleus disintegrate and each cell forms a new macronucleus from its micronucleus. 6. Both cells are now genetically identical. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sporozoans Sporozoans Feeding Sporozoans do not move on their own—they are parasitic. Sporozoans are parasites of a wide variety of organisms, including worms, fish, birds, and humans. Heterotrophic Plasmodium (cause malaria disease) in human blood Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sporozoans Reproduction Sporozoans reproduce by means of spores The spores are able to attach themselves to a host cell, penetrate it and then live within it as parasites. Plasmodium in human blood Spore phase of Plasmodium Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sporozoans Many sporozoans have complex life cycles that involve more than one host. Copyright Pearson Prentice Hall

Animal-like Protists and Disease Malaria Malaria is one of the world’s most serious infectious diseases, killing as many as 2 million people each year. The sporozoan Plasmodium, which causes malaria, is carried by the female Anopheles mosquito. Copyright Pearson Prentice Hall

Animal-like Protists and Disease Malarial Infection Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. Copyright Pearson Prentice Hall

Animal-like Protists and Disease A female Anopheles mosquito bites a human infected with malaria and picks up Plasmodium gamete cells. Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. Copyright Pearson Prentice Hall

Animal-like Protists and Disease The sexual phase of the Plasmodium life cycle takes place inside the mosquito. Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Copyright Pearson Prentice Hall

Animal-like Protists and Disease Infected mosquito bites another human, injecting saliva that contains Plasmodium sporozoites. Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Plasmodium sporozoites Copyright Pearson Prentice Hall

Animal-like Protists and Disease Sporozoites infect liver cells and multiply asexually. Plasmodium sporozoites Liver Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. Copyright Pearson Prentice Hall

Animal-like Protists and Disease Infected liver cells burst, releasing Plasmodium cells called merozoites that infect red blood cells. Plasmodium sporozoites Liver Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. Merozoites Liver cells burst Copyright Pearson Prentice Hall

Animal-like Protists and Disease Merozoites reproduce asexually inside red blood cells and eventually the infected cells burst. Plasmodium release toxins, the toxins are transported throughout the body and the symptoms of malaria are produced. Merozoites Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. Red blood cells Copyright Pearson Prentice Hall

Ecology of Animal-like Protists Harmful Relationships: Many protists are parasitic, which can affect plants, all types of animals and even other protists. ex. plasmodium – malaria, Trypanosoma – African sleeping sickness, Entamoeba – dysentery Details on diseases caused by protists: p503 Helpful Relationships: Many animal-like protists are essential to the living world. Some live symbiotically within other organisms. Some recycle nutrients from dead organic matter. Some live in water, where they are eaten by tiny animals, which in turn serve as food for larger animals. Copyright Pearson Prentice Hall

Ecology of Animal-like Protists Some animal-like protists are beneficial to other organisms. The protist Trichonympha lives within the digestive systems of termites. It breaks down cellulose, allowing termites to digest wood. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 20–2 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 20–2 Structures found in sarcodines that are used for feeding and movement are known as pseudopods. flagella. cilia. food vacuoles. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 20–2 The structure found in most ciliates that contains a “reserve copy” of all the cell's genes is the macronucleus. micronucleus. trichocysts. contractile vacuole. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 20–2 One way to classify the various groups of animal-like protists is by the presence of a nuclear membrane. the presence of mitochondria. their means of movement. the number of contractile vacuoles. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 20–2 Malaria is caused by the sporozoan Plasmodium. Anopheles. Amoeba. Paramecium. Copyright Pearson Prentice Hall

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