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© 2015 Pearson Education, Inc. PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Chapter 17.

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Presentation on theme: "© 2015 Pearson Education, Inc. PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Chapter 17."— Presentation transcript:

1 © 2015 Pearson Education, Inc. PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Chapter 17 Lecture by Edward J. Zalisko The Evolution of Plant and Fungal Diversity

2 © 2015 Pearson Education, Inc. D IVERSITY OF F UNGI

3 © 2015 Pearson Education, Inc. 17.12 Fungi absorb food after digesting it outside their bodies Fungi are heterotrophic eukaryotes, secrete powerful enzymes to digest their food externally, and acquire their nutrients by absorption. Fungi are not plants. They do not photosynthesize. They do not have cellulose.

4 © 2015 Pearson Education, Inc. 17.12 Fungi absorb food after digesting it outside their bodies Most fungi consist of a mass of threadlike hyphae. The mass of hyphae is called a mycelium. In most fungi, the hyphae consist of chains of cells separated by cross-walls that have pores large enough to allow ribosomes, mitochondria, and even nuclei to flow from cell to cell. Mycelium on fallen conifer needles

5 © 2015 Pearson Education, Inc. Figure 17.12b-0 Hyphae Mycelium Reproductive structure Spore-producing structures (tips of hyphae)

6 © 2015 Pearson Education, Inc. 17.12 Fungi absorb food after digesting it outside their bodies Fungal hyphae are surrounded by a cell wall made of chitin instead of cellulose. Some fungi are parasites, obtaining their nutrients at the expense of living plants or animals.

7 © 2015 Pearson Education, Inc. 17.12 Fungi absorb food after digesting it outside their bodies Mycorrhizae represent a symbiotic relationship between fungi and plant roots and absorb essential materials from the soil and make them available to the plant. Sugars produced by the plant through photosynthesis nourish the fungus, making the relationship mutually beneficial.

8 © 2015 Pearson Education, Inc. 17.13 Fungi produce spores in both asexual and sexual life cycles Fungal reproduction typically involves the release of vast numbers of haploid spores, which are transported easily over great distances by wind or water.

9 © 2015 Pearson Education, Inc. 17.13 Fungi produce spores in both asexual and sexual life cycles A spore that lands in a moist place where food is available germinates and produces a new haploid fungus by mitosis. Spores can be produced either sexually or asexually.

10 © 2015 Pearson Education, Inc. 17.13 Fungi produce spores in both asexual and sexual life cycles In many fungi, sexual reproduction involves mycelia of different mating types. Hyphae from each mycelium release signaling molecules and grow toward each other. 1.When the hyphae meet, their cytoplasms fuse. But this fusion of cytoplasm is often not followed immediately by the fusion of “parental” nuclei. Thus, many fungi have what is called a heterokaryotic stage, in which cells contain two genetically distinct haploid nuclei.

11 © 2015 Pearson Education, Inc. 17.13 Fungi produce spores in both asexual and sexual life cycles 2.Hours, days, or even centuries may pass before the parental nuclei fuse, forming the usually short- lived diploid phase. 3.Zygotes undergo meiosis, producing haploid spores. The specialized structures in which these spores form are used to classify fungi. 4.In asexual reproduction, spore-producing structures arise from haploid mycelia that have undergone neither a heterokaryotic stage nor meiosis. Many fungi that reproduce sexually can also produce spores asexually.

12 © 2015 Pearson Education, Inc. 17.13 Fungi produce spores in both asexual and sexual life cycles A mold is any rapidly growing fungus that reproduces asexually by producing spores. Yeast refers to any single-celled fungus. There are over 100,000 described species of fungi. Suspected but as-yet-undescribed species may number as many as 1.5 million.

13 © 2015 Pearson Education, Inc. Figure 17.14a Chytrids Zygomycetes (zygote fungi) Glomeromycetes (arbuscular mycorrhizal fungi) Ascomycetes (sac fungi) Basidiomycetes (club fungi)

14 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Chytrids are the only fungi with flagellated spores and are thought to represent the earliest lineage of fungi. Chytrid fungi are common in lakes, ponds, and soil and linked to the widespread decline of amphibian species.

15 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Zygomycetes, or zygote fungi, are characterized by their protective zygosporangium, where zygotes produce haploid spores by meiosis. This diverse group includes fast-growing molds that attack, for example, bread peaches, strawberries, sweet potatoes some animals.

16 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Glomeromycetes form a distinct type of mycorrhizae, in which hyphae that invade plant roots branch into treelike structures. About 80% of all plants have symbiotic partnerships with glomeromycetes, which deliver minerals to plants while receiving organic nutrients in exchange.

17 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Ascomycetes, or sac fungi, form saclike structures called asci that produce spores in sexual reproduction, live in marine, freshwater, and terrestrial habitats, and range in size from unicellular yeasts to elaborate morels and cup fungi. Edible morels Cup fungus

18 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Some ascomycetes live with green algae or cyanobacteria in symbiotic associations called lichens.

19 © 2015 Pearson Education, Inc. 17.17 Lichens are symbiotic associations of fungi and photosynthetic organisms Lichens consist of symbiotic associations of algae or cyanobacteria within a mass of fungal hyphae. Many lichen associations are mutualistic. The fungus receives food from its photosynthetic partner. The fungal mycelium helps the alga absorb and retain water and minerals.

20 © 2015 Pearson Education, Inc. 17.17 Lichens are symbiotic associations of fungi and photosynthetic organisms Lichens are important pioneers on new land, where they help to form soil, can withstand severe drought, and are sensitive to air pollution, because they obtain minerals from the air. The death of lichens is often a sign that air quality in an area is deteriorating.

21 © 2015 Pearson Education, Inc. Figure 17.17b Algal cell Fungal hyphae

22 © 2015 Pearson Education, Inc. Figure 17.17c

23 © 2015 Pearson Education, Inc. 17.14 Fungi are classified into five groups Basidiomycetes, or club fungi, include common mushrooms, puffballs, and shelf fungi and are named for their club-shaped, spore-producing structure called a basidium. These fungi include important forest decomposers and particularly destructive plant parasites called rusts and smuts.

24 © 2015 Pearson Education, Inc. Figure 17.14e-0 Mushrooms A puffball Shelf fungi

25 © 2015 Pearson Education, Inc. 17.15 CONNECTION: Fungi have enormous ecological benefits Fungi supply essential nutrients to plants through symbiotic mycorrhyizae, along with prokaryotes are essential decomposers in ecosystems, breaking down organic matter and restocking the environment with vital nutrients essential for plant growth, and may also be used to digest petroleum products to clean up oil spills and other chemical messes. Scientists have proposed that symbioses with fungi were crucial to the colonization of land by plants.

26 © 2015 Pearson Education, Inc. 17.16 CONNECTION: Fungi have many practical uses Fungi have many practical uses for humans. We eat mushrooms and cheeses modified by fungi. Yeasts produce alcohol and cause bread to rise. Some fungi provide antibiotics, like penicillin, that are used to treat bacterial disease. Fungi figure prominently in molecular biology and in biotechnology. Yeasts, for example, are often used to study molecular genetics of eukaryotes. Fungi may play a major role in the future production of biofuels from plants.

27 © 2015 Pearson Education, Inc. Figure 17.16b Staphylococcus aureus (bacteria) Penicillium (mold) Zone of inhibited growth Blue cheese

28 © 2015 Pearson Education, Inc. 17.19 CONNECTION: Parasitic fungi harm plants and animals Of the 100,000 known species of fungi, about 30% are either parasites or pathogens in or on plants. About 80% of plant diseases are caused by fungi. Between 10% and 50% of the world’s fruit harvest is lost each year to fungal attack. A variety of fungi, including smuts and rusts, infect grain crops.

29 © 2015 Pearson Education, Inc. Figure 17.19c Ergots Corn smut

30 © 2015 Pearson Education, Inc. 17.19 CONNECTION: Parasitic fungi harm plants and animals Only about 50 species of fungi is parasitic on animals. Fungal diseases of the skin include ringworm, named because it appears as circular red areas on the skin, athlete’s foot, also caused by the ringworm fungus, vaginal yeast infections, and deadly lung diseases that produce tuberculosis-like symptoms in the lungs.


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