Kingdom Fungi (JiTT) (1).ppt

Kingdom Fungi  Kingdom Fungi I. General Characteristics II. Life Cycles III. Fungal Diversity IV. Ecological Roles of Fungi  Learning Objectives 1. Describe the relationship between hyphae and mycelium 2. Explain the nutrition modes of fungi 3. Explain how specializations of hyphae...

Kingdom Fungi  Kingdom Fungi I. General Characteristics II. Life Cycles III. Fungal Diversity IV. Ecological Roles of Fungi  Learning Objectives 1. Describe the relationship between hyphae and mycelium 2. Explain the nutrition modes of fungi 3. Explain how specializations of hyphae lead to nutritional advantages 4. Explain the role of asexual and sexual reproduction in the life cycle of fungi 5. Describe the main characteristics of each of the five main fungi groups 6. Evaluate the importance of decomposition performed by fungi in an ecosystem 7. Explain the economic importance of parasitic and pathogenic fungi 8. Describe the symbiotic relationships between fungi and animals 9. Describe the symbiotic relationships between fungi and plants  I. General Characteristics A. Diversity 1. Fungi are diverse and widespread 2. They are essential for the well-being of most terrestrial ecosystems because they break down organic material and recycle vital nutrients 3. About 100,000 species of fungi have been described 4. It is estimated there are actually 1.5 million species of fungi B. Nutrition 1. Fungi are heterotrophs and absorb nutrients from outside of their body 2. Fungi use enzymes to break down a large variety of complex molecules into smaller organic compounds 3. The versatility of these enzymes contributes to fungi’s ecological success 4. Fungi exhibit diverse lifestyles a. Decomposers b. Parasites c. Mutualists C. Morphology 1. Some species grow as either filaments or yeasts; others grow as both 2. The morphology of multicellular fungi enhances their ability to absorb nutrients 3. Fungi consist of mycelia, networks of branched hyphae adapted for absorption 4. A mycelium’s structure maximizes its surface area-to-volume ratio 5. Fungal cell walls contain chitin 6. Most fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement of organelles 7. Coenocytic fungi lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei D. Specialized hypha 1.Some fungi have hyphae specialized to capture prey 2.Some unique fungi have specialized hyphae called haustoria that allow them to penetrate the tissues of their host 3. Most vascular plants have mycorrhizae, mutually beneficial relationships between fungi and plant roots 4. Mycorrhizal fungi deliver phosphate ions and minerals to plants Types: a) Ectomycorrhizal fungi (do not penetrate root cells) b) Arbuscular mycorrhizal fungi (penetrate root cells)  What makes up the structure of fungi? a. The body is made of septa, which create an interwoven mass of mycelium filaments. b. The body is made of hyphae, which create an interwoven mass of septa filaments. c. The body is made of a mycelium, which is an interwoven mass of hyphae. d. The body is made of cellulose, which forms an interwoven mass of subsurface roots. © 2014 Pearson Education, Inc. Which of the following statements about mycorrhizae is false? a) They are important in natural systems and agriculture. b) Almost all vascular plants have them. c) Foresters inoculate pine seedlings with them to promote growth. d) They colonize soils by dispersing spores that form new mycelia. e) They are in a commensalistic relationship with plants. © 2014 Pearson Education, Inc. You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus? a) presence of mitochondria b) absence of chloroplasts c) presence of nuclei d) presence of chitinous cell walls © 2014 Pearson Education, Inc.  II. Life Cycles A. Sexual Reproduction 1. Fungal nuclei are normally haploid, with the exception of transient diploid stages formed during the sexual life cycles 2. Sexual reproduction requires the fusion of hyphae from different mating types 3. Fungi use sexual signaling molecules called pheromones to communicate their mating type 4. Plasmogamy is the union of cytoplasm from two parent mycelia 5. In most fungi, the haploid nuclei from each parent do not fuse right away; they coexist in the mycelium, called a heterokaryon 6. In some fungi, the haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic 7. Hours, days, or even centuries may pass before the occurrence of karyogamy, nuclear fusion 8. During karyogamy, the haploid nuclei fuse, producing diploid cells 9. The diploid phase is short-lived and undergoes meiosis, producing haploid spores 10. The paired processes of karyogamy and meiosis produce genetic variation  How could you tell whether fungal offspring were produced by asexual reproduction? a. Use a microscope to see whether they are multinucleate. b. Use a microscope to see whether they have analogous structures. c. Analyze the DNA via gel electrophoresis to determine whether it is genetically identical to the parental DNA. d. Analyze the DNA via gel electrophoresis to determine whether it is genetically similar to the parental DNA. © 2014 Pearson Education, Inc. B. Asexual Reproduction 1.In addition to sexual reproduction, many fungi can reproduce asexually 2.Molds produce haploid spores by mitosis and form visible mycelia  Other fungi that can reproduce asexually are yeasts, which are single cells Instead of producing spores, yeasts reproduce asexually by simple cell division and the pinching of “bud cells” from a parent cell Some fungi can grow as yeasts and as filamentous mycelia  III. Fungal Diversity Molecular analyses have helped clarify evolutionary relationships among fungal groups, although areas of uncertainty remain A. Phylum Chytridiomycota 1. Chytrids are found in freshwater and terrestrial habitats 2. They can be decomposers, parasites, or mutualists 3. Molecular evidence supports the hypothesis that chytrids diverged early in fungal evolution 4. Chytrids are unique among fungi in having flagellated spores, called zoospores B. Phylum Zygomycota 1.The zygomycetes exhibit great diversity of life histories 2.They include fast-growing molds, parasites, and commensal symbionts 3.The life cycle of black bread mold (Rhizopus stolonifer) is fairly typical of the phylum 4.Its hyphae are coenocytic 5.Asexual sporangia produce haploid spores 6. The zygomycetes are named for their sexually produced zygosporangia 7. Zygosporangia are the site of karyogamy and then meiosis 8. Zygosporangia, which are resistant to freezing and drying, can survive unfavorable conditions 9. Some zygomycetes, such as Pilobolus, can actually “aim” their sporangia toward conditions associated with good food sources C. Phylum Glomeromycota The glomeromycetes were once considered zygomycetes They are now classified in a separate clade Glomeromycetes form arbuscular mycorrhizae D. Phylum Ascomycota 1.Ascomycetes live in marine, freshwater, and terrestrial habitats 2. Ascomycetes produce sexual spores in saclike asci contained in fruiting bodies called ascocarps 3. Ascomycetes are commonly called sac fungi 4. Ascomycetes vary in size and complexity from unicellular yeasts to elaborate cup fungi and morels 5. Ascomycetes include plant pathogens, decomposers, and symbionts 6. Ascomycetes reproduce asexually by enormous numbers of asexual spores called conidia 7. Conidia are not formed inside sporangia; they are produced asexually at the tips of specialized hyphae called conidiophores 8. Neurospora crassa, a bread mold, is a model organism with a well- studied genome Which of the following phyla includes aquatic, flagellated fungi? a) Ascomycota b) Basidiomycota c) Chytridiomycota d) Zygomycota © 2014 Pearson Education, Inc. E. Phylum Basidiomycota 1.Basidomycetes (phylum Basidiomycota) include mushrooms, puffballs, and shelf fungi, mycorrhizae, and plant parasites 2.The phylum is defined by a clublike structure called a basidium, a transient diploid stage in the life cycle 3.The basidiomycetes are also called club fungi 4.Many basidiomycetes are decomposers of wood 5. The life cycle of a basidiomycete usually includes a long-lived dikaryotic mycelium 6. In response to environmental stimuli, the mycelium reproduces sexually by producing elaborate fruiting bodies call basidiocarps 7. Mushrooms are examples of basidiocarps 8. The numerous basidia in a basidiocarp are sources of sexual spores called basidiospores You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this? a) zygomycete b) chytrid c) deuteromycete d) ascomycete © 2014 Pearson Education, Inc. All of the following are lineages of fungi except a) chytrids. b) zygomycetes. c) glomeromycetes. d) conidia. © 2014 Pearson Education, Inc. IV. Ecological Roles of Fungi A. Decomposition 1. Fungi are efficient decomposers of organic material including cellulose and lignin 2. They perform essential recycling of chemical elements between the living and nonliving world 3. Fungi are also used in bioremediation projects  What type of fungus forms a fairy ring, and what does the diameter of this ring indicate? a. A zygomycete; the extent to which the fungus is infected with a protist b. A lichen; the extent to which the fungus is in a symbiotic relationship with a cyanobacterium c. A basidiomycete; the age of the fungus d. An ascomycete; the amount of antibiotic the fungus has produced © 2014 Pearson Education, Inc. B. Fungus-plant Mutualism 1. Mycorrhizae are enormously important in natural ecosystems and agriculture 2. Plants harbor harmless symbiotic endophytes, fungi that live inside leaves or other plant parts 3. Endophytes make toxins that deter herbivores and defend against pathogens 4. Most endophytes are ascomycetes C. Fungus-animal Mutualism Some fungi share their digestive services with animals These fungi help break down plant material in the guts of cows and other grazing mammals Many species of ants use the digestive power of fungi by raising them in “farms” D. Lichens 1. A lichen is a symbiotic association between a photosynthetic microorganism and a fungus 2. Millions of photosynthetic cells are held in a mass of fungal hyphae 3. The photosynthetic component is green algae or cyanobacteria 4. The fungal component is most often an ascomycete 5. The algae provide carbon compounds, cyanobacteria also provide organic nitrogen, and fungi provide the environment for growth 6. The fungi of lichens can reproduce sexually and asexually 7. Asexual reproduction is by fragmentation or the formation of soredia, small clusters of hyphae with embedded algae  Lichens are important pioneers on new rock and soil surfaces Lichens may have helped the colonization of land by plants 550–600 million years ago Lichens are sensitive to pollution, and their death can be a warning that air quality is deteriorating Lichens are a) mutually beneficial relationships between fungi and plant roots. b) symbiotic associations between photosynthetic organisms and fungi. c) a type of plant pathogen. d) a type of marine eukaryote. e) single-celled, flagellated protist ancestors of fungi. © 2014 Pearson Education, Inc.  What would happen to a lichen if the cyanobacteria or green algae were to die? a. The fungi would move to another location. b. The fungi would die. c. The fungi would undergo asexual reproduction. d. The fungi would begin to undergo photosynthesis. © 2014 Pearson Education, Inc. E. Pathogenic Fungi 1.About 30% of known fungal species are parasites or pathogens, mostly on or in plants 2.Each year, 10% to 50% of the world’s fruit harvest is lost due to fungi 3.Some fungi that attack food crops are toxic to humans 4. Animals are much less susceptible to parasitic fungi than are plants 5. The chytrid Batrachochytrium dendrobatidis might be the cause of the recent decline in amphibians worldwide