Kingdom Fungi Molds, Sac Fungi, Mushrooms, and Lichens Essential Question(s): What makes fungi have their own kingdom? Objectives: 1. Student will be able to describe the characteristic features in the kingdom Fungi. 2. Student will be able to compare and contrast the fungi with plants and animals in terms of body plan and life cycle. 3. Student will recognize and discuss various forms of fungi and their respective reproductive cycles. Fungi are a diverse group of organisms that have two major roles; decomposition of organic materials and to symbiotically aid algae and plants. Examine the chart below showing basic characteristics of fungi. Cell Eukaryotic, no chloroplast present, cell wall made of chitin Feature Body Plan Nutrition Life Cycle Multicellular (hyphae) or Unicellular Heterotrophs by extracellular digestion followed by absorption. Haploid (multicellular) and diploid (unicellular) phase Introduction: Fungi are not photosynthetic and therefore cannot produce their own food like plants do. Much like animals, fungi are heterotrophs. However fungi Figure 1. Fungal forms of either singles cells or hyphae (filaments) 1
are absorptive meaning they do not ingest their foods are first extracellularly digested and then absorbed. Fungi are saprophytes meaning they feed on dead or decaying organic matter. The hyphae (thread like structures), are the most basic structure of fungi and contain many nuclei distributed throughout the cytoplasm. Sometimes the hyphae are divided into compartments by cross walls called septa. Fungi with cross walls are called septate fungi, while fungi without cross walls are called coenocytic fungi. A collection of hyphae is called mycellium. The mycellium can penetrate water, soil, and living tissue in order to absorb nutrients through the tips of the hyphae that Figure 2: Chytridiomycota, Zygomycota, Basidiomycota, and Ascomycota are the four major phyla in the Fungi Kingdom produce digestive enzymes to digest organic material. The soluble products are absorbed into the hyphae. There are four major phyla, Ascomycota, Basidiomycota, Zygomycota, and Chytridiomycota. Classification of fungi is determined based on differences of specialized structures during their reproductive cycles. Fungi reproduce asexually most often but they do have a sexual reproductive phase. Asexual Reproduction: Asexual reproduction occurs through mitosis of haploid cells in three different methods. Spores are produced in reproductive structures called sporangia, and conidiophores, among others. Spores are well equipped to endure harsh environments and when optimal conditions Figure 3. General life cycle of fungi. arise, they have the ability to develop into a 2
fully functional organism. During budding, another method of asexual reproduction, a cell arises and grows from the original cell and then detaches itself and develops into a new organism. In yeast, budding usually occurs in the uneven distribution of the cytoplasm through mitosis. Fragmentation is the breakage of an organism into one or more units that can individually give rise to new mycelium. Sexual Reproduction: Sexual reproduction of fungi begins when hyphae from two genetically different individuals meet. Once the hyphae meet the two haploid cells will often fuse their cytoplasms in a process called plasmogamy having two nuclei per cell (dikaryotic). Karyogamy is the fusion of the two nuclei to become diploid zygotes. The generalized life cycle of a fungus has four important features: 1) during most of its life cycle the nuclei in mycelium are in the haploid state. 2) Mitosis occurs to produce gametes during which haploid cells are differentiated. 3) Soon after formation of the zygote (diploid), meiosis takes place. 4) Meiosis produces more haploid cells called spores. Spores are not gametes but rather haploid cells that develop into a haploid organism through mitosis. 3
Phylum Illustration Common name Reproductive Characteristic Chytridiomycota Chytrids Zygomycota Zygote Fungi Ascomycota Sac Fungi Basidiomycota Club Fungi Figure 4: Summary table of four fungi phyla, their general appearance, and reproductive structures. Chytridiomycota: These are the group of fungi known as the chytrids, whose distinctive characteristic is their flagellated gametes. Chytrids have a well defined sporophyte diploid stage. They are responsible for a significant reduction on the populations of many amphibians. Slides 1) Obtain 2 common chytrids : Allomyces or Chytridium and prepare a wet mount to examine morphology. a) Draw your observations from the wet mounts. b) Are hyphae apparent? 4
Zygomycota: Zygomycetes are most commonly known as the bread molds. They are characterized by their sexual structure called the zygosporangium, the short diploid stage. The vegetative hyphae lack septae versus the reproductive structures which are septate. The most common genus of the bread mold is Rhizopus. Refer to these figures below to become familiar with sexual and asexual reproduction of zygomycetes. Figure 5. Reproductive structures of Rhizopus (bread mold); Rhizopus reproductive structures. 5
Figure 6: Life cycle of Rhizopus, bread mold) Observe: 1) Obtain a petri plate with moldy bread that has been moistened and exposed to air from your instructor 2) Use dissecting microscope to examine mycelia, note if they are tangled. a) Describe the texture and the color of the molds. Where is the pigment concentrated on each mold? b) How many species of molds do you have? c) Why is it significant that bread molds have meiosis (as in plants) to produce spores and asexual spores produced my mitosis? 6
3) Observe prepared slide of Rhizopus conjugation and Rhizopus Sporangia under a microscope. Ascomycota: Ascomycetes (sac fungi) have a sac shaped reproductive Figure 7: Rhizopus Conjugation 40X: Lactophenol alcohol cotton blue structure called the ascus. Acomycetes are a diverse group that includes yeasts, truffles, morels, and some molds. Some species like Penicillium lack the sexual stage. Asexual reproduction takes place by the formation of conidia, specialized spores. Each conidium may contain one or more nuclei. In ascomycetes conidia form on the surface of the conidiophore unlike the spores of Rhizopus which form within the sporangia. Yeasts are a type of ascomycete whose bodies are not made from hyphae and are unicellular. They have both sexual and asexual reproductive cycles but the most prevalent cycle is asexual reproduction by mitosis. Figure 8: Penicillium Conidia 100x Figure 9: Yeast, Saccharomyces Slide: 1) Using a microscope to observe Penicillium Conidiophores prepared slide,penicillium Conidia 100X. 2) Obtain a stock culture of Saccharomyces (yeast) and prepare a wet mount by using only a small amount. 7
a. Describe the morphology of yeast cells. b. Compare the yeast hyphae to that of mold hyphae. 3) Obtain a culture plate of living Aspergillus, Penicillium, or Neurospora and examine the soft texture of the colonies under a dissecting microscope. Basidiomycota: Figure 10. Basidium schematic Basidiomycetes are the most familiar fungi that include puff balls, shelf fungi, and mushrooms. This group is characterized by its reproductive structure called the basidiocarp, a tight bundle of hyphae. The basidiocarp forms a cap and gills. Observe: 1) Examine fresh mushrooms (earthstar). Using a scalpel obtain a thin slice and observe under a microscope to look for spores on the gills of the mushroom. a. Where would you find dikaryotic cells, haploid cells, and Figure: 11 Coprinus Mushroom 8
diploid cells? 2) Observe the prepared slide Coprinus Mushroom under a microscope to observe the spores and hyphae. Lichens A lichen consists of two organisms living together in a symbiotic relationship. In most cases the two organisms are fungi (ascomycete) with a photosynthetic algae (protist) or cyanobacterium. The algae provides the sugars produced by photosynthesis while the fungus provides protection and nutrients used by the alga. This symbiotic relationship allows both organisms to proliferate in harsh environments. 1) Observe the prepared slide of lichen thallus a. Draw your observation labeling the algal cells and fungal cells. 2) Observe the whole lichen. Figure 9: Lichen Thallus 100X Figure: 12 Lichen Thallus a. Where would you expect to see lichens. Why? 9
Sources: 1. Content Survey of the Fungi Kingdom: Molds, Sac Fungi, Mushrooms, and Lichens 2. De Anza Lab Manual http://faculty.deanza.edu/heyerbruce/bio6a Image Sources: Figure 1 Fungal forms http://gallery4share.com/s/saccharomyces.html, https://www.google.com/search?q=fungal+forms&rlz=1c1kmzb_enus545us545&espv=2&biw=1440&bih=799 &source=lnms&tbm=isch&sa=x&ved=0cayq_auoawovchmij5s2k5h6xgivyjench0l0wkz#tbm=isch&q= hyphae+filaments&imgrc=h 5VSlO1nAQcFM%3A Figure 2 Four major fungi phyla http://faculty.collegeprep.org/~bernie/sciproject/project/kingdoms/fungi5/fungi_evolution.htm Figure 3 General Life cycle of fungi http://www.tanelorn.us/data/mycology/myc_life.htm Figure 4 Summary table of fungi: http://www.apsnet.org/edcenter/intropp/pathogengroups/pages/oomycetes.aspx ʺSpizellomyceteʺ by Author and original uploader was MidgleyDJ at en.wikipedia Transferred from en.wikipedia to Commons.. Licensed under CC BY SA 2.5 via Wikimedia Commons https://commons.wikimedia.org/wiki/file:spizellomycete.jpg#/media/file:spizellomycete.jpg https://sharon taxonomy2010 p2.wikispaces.com/fungi ʺSmardz Morchella Ejdzej 2006ʺ. Licensed under CC BY SA 3.0 via Wikimedia Commons https://commons.wikimedia.org/wiki/file:smardz Morchella Ejdzej 2006.jpg#/media/File:Smardz Morchella Ejdzej 2006.jpg ʺAscocarp2ʺ by Debivort. Licensed under CC BY SA 3.0 via Wikimedia Commons https://commons.wikimedia.org/wiki/file:ascocarp2.png#/media/file:ascocarp2.png https://commons.wikimedia.org/wiki/file:amanita_muscaria_(fly_agaric).jpg https://www.studyblue.com/notes/note/n/bio 211 study guide 2014 15 dr john fowler/deck/12725408 Figure 5 Bread Mold http://www.biologyjunction.com/fungi_notes_b1.htm Figure 6 Bread Mold life cycle https://www.google.com/search?q=chytrids+public+domain&biw=977&bih=771&source=lnms&tbm=isch&sa= X&ei=OMyRVajiOsbcQH6x4CoDA&ved=0CAYQ_AUoAQ#tbm=isch&q=rizopus+reproductive+cycle+public+ domain&imgrc=n3aoebosfa_edm%3a 10
Figure 10 ʺBasidium schematicʺ by Debivort From English Wikipedia. Licensed under CC BY SA 3.0 via Wikimedia Commons https://commons.wikimedia.org/wiki/file:basidium_schematic.svg#/media/file:basidium_schematic.svg 11