Biology. Slide 1of 34. End Show. Copyright Pearson Prentice Hall

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1 Biology 1of 34

2 20 5 Funguslike Protists 2of 34

3 20 5 Funguslike Protists Similarities and differences between funguslike protists and fungi Like fungi, g, funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter. No photosynthesis. Unlike most true fungi, funguslike protists contain centrioles. They also lack the chitin cell walls of true fungi. Grow in damp, nutrient rich environments Funguslike protist Fungus 3of 34

4 20 5 Funguslike Protists Two phyla of Fungulike Protists Slime Molds Water Molds 4of 34

5 20 5 Funguslike Protists Slime Molds Slime molds Defining characteristics of the slime molds Slime molds are funguslike protists that play key roles in recycling organic material. At one stage of their life cycle, slime molds look just like amoebas. At other stages, they form moldlike clumps that produce spores, almost like fungi. 5of 34

6 20 5 Funguslike Protists Video Mold Time-lapse (3min): 8Xpy0 6of 34

7 20 5 Funguslike Protists Slime Molds Two groups of slime molds are recognized: Cellular slime molds, whose individual cells remain separated by cell membranes, during every phase of the mold's life cycle. Acellular slime molds, which pass through a stage in which its cells fuse to form large cells with many nuclei. 7of 34

8 20 5 Funguslike Protists Slime Molds Cellular Slime Molds Most cellular slime molds live as free-living cells that are not easily distinguishable from soil amoebas. In nutrient-rich soils, these amoeboid cells reproduce sexually and produce diploid zygotes. 8of 34

9 20 5 Funguslike Protists Slime Molds Life Cycle of a Cellular Slime Mold Fruiting body Emerging Solitary cell Spores amoebas Aggregated amoebas Zygote Fruiting body Migrating colony 9of 34

10 20 5 Funguslike Protists Slime Molds When food is scarce, the cells produce spores. They emit chemicals to attract cells of the same species. Cells gather into a colony that functions like one organism. 10 of 34

11 20 5 Funguslike Protists Slime Molds The colony moves slightly, then stops to produce a fruiting body, a slender reproductive structure that produces spores. Then the spores are scattered from the fruiting body. Each spore produces one cell, starting ti the cycle again. 11 of 34

12 20 5 Funguslike Protists Video of cellular slime mold aggregating and forming fruiting bodies: / C 12 of 34

13 20 5 Funguslike Protists Slime Molds Acellular Slime Molds Acellular l slime molds begin as amoeba-like cells. When they aggregate, their cells fuse to produce structures with many nuclei known as plasmodium. Eventually, the fruiting body called sporangium grows up from the plasmodium. 13 of 34

14 20 5 Funguslike Protists Slime Molds Life Cycle of an Acellular Slime Mold Mature sporangium Spores Germinating Young Feeding sporangium Mature plasmodium plasmodium Fertilization Zygote 14 of 34

15 20 5 Funguslike Protists Slime Molds Fruiting bodies, or sporangia, arise from the plasmodium (no link with the malaria!). The sporangia produce haploid spores by meiosis. Mature sporangium Young sporangium Mature plasmodium Feeding plasmodium Zygote 15 of 34

16 20 5 Funguslike Protists Slime Molds Spores scatter and germinate into flagellated cells. Cells fuse to produce diploid zygotes. Spores Germinating 16 of 34

17 20 5 Funguslike Protists Water Molds Water Molds (Oomycetes) Defining characteristics of the water molds Oomycetes or water molds thrive on dead or decaying organic matter in water. Some water molds are plant parasites on land. The name Oomycete means egg fungi and refer to the large egg shaped female gamete oogonium 17 of 34

18 20 5 Funguslike Protists Water Molds Water molds produce thin filaments known as hyphae. Water molds have cell walls made of cellulose and produce motile spores, two traits that fungi do not have. Water molds reproduce both sexually and asexually. 18 of 34

19 20 5 Funguslike Protists Water Molds Life Cycle of a Water Mold FERTILIZATION MEIOSIS SEXUAL REPRODUCTION ASEXUAL REPRODUCTION 19 of 34

20 20 5 Funguslike Protists Water molds In asexual reproduction, portions of the hyphae develop into zoosporangia,, which are spore cases. Mycelium (2N) Flagellated Spores (N) Hypha Zoosporangium Germination and mitosis ASEXUAL REPRODUCTION 20 of 34

21 20 5 Funguslike Protists Water Molds Each produces flagellated spores that swim in search of food. Mycelium (2N) Flagellated Spores (N) Zoosporangium Germination and mitosis Hypha ASEXUAL REPRODUCTION 21 of 34

22 20 5 Funguslike Protists Water Molds When they find food, the spores develop into hyphae, which then grow into new organisms. Mycelium (2N) Flagellated Spores (N) Zoosporangium Germination and mitosis Hypha ASEXUAL REPRODUCTION 22 of 34

23 20 5 Funguslike Protists Water molds Sexual reproduction occurs in specialized structures formed by the hyphae. Antheridium Egg cells (N) FERTILIZATION Zygotes (2N) MEIOSIS Mycelium (2N) Oogonium Flagellated spores (N) Male nuclei (N) Fertilization Zoosporangium SEXUAL REPRODUCTION 23 of 34

24 20 5 Funguslike Protists Water molds The antheridium produces male nuclei. Antheridium Egg cells (N) FERTILIZATION Zygotes (2N) MEIOSIS Mycelium (2N) Oogonium Flagellated spores (N) Male nuclei (N) Fertilization Zoosporangium SEXUAL REPRODUCTION 24 of 34

25 20 5 Funguslike Protists Water molds The oogonium produces female nuclei. Antheridium Egg cells (N) FERTILIZATION Zygotes (2N) MEIOSIS Mycelium (2N) Oogonium Flagellated spores (N) Male nuclei (N) Fertilization Zoosporangium SEXUAL REPRODUCTION 25 of 34

26 20 5 Funguslike Protists Water molds Fertilization occurs within the oogonium, and the spores that form develop into new organisms. Antheridium Egg cells (N) FERTILIZATION Zygotes (2N) MEIOSIS Mycelium (2N) Oogonium Male nuclei (N) Flagellated spores (N) Fertilization Zoosporangium SEXUAL REPRODUCTION 26 of 34

27 20 5 Funguslike Protists Video Discharge of water mold zoospores (36sec) 27 of 34

28 20 5 Funguslike Protists Ecology of Funguslike Protists Ecology of Funguslike Protists Slime molds and water molds recycle organic material. After organisms die, their tissues are broken down by slime molds, water molds, and other decomposers. 28 of 34

29 20 5 Funguslike Protists Ecology of Funguslike Protists Some funguslike protists can harm living things. Land-dwelling dwelling water molds cause a number of plant diseases, including mildews and blights. A water mold was responsible for the Great Potato Famine in the 1800s, causing the potato blight 29 of 34