2 How do Fungi acquire nutients? They are Heterotrophs that get nutrition from absorption-- secretes hydrolytic enzymes into food then absorbs-- therefore they are decomposers, parasites, or mutualistic symbionts (Lichens – fungi and algae living together)Because of this mode of nutrition, fungi have evolved what structure to provide for both extensive surface area and rapid growth?Mycelium – interwoven mats made of hyphaeHyphae – small threads made of tubular cell walls (made of chitin)surround the plasma membrane. They are divided into cells by cross walls called septa.
5 How do cell walls of fungi differ from the cell walls of plants? Plants cell walls are made of celluloseFungi cell walls are made of chitinWhat are the septa comparable to in plant cells (even though septa are bigger)?PlasmodesmataDefine these terms:Mycelium – Densely branched network of hyphae in a fungusSepta – A cross wall that divides a fungal hypha into cells. Pores are large enough to allow ribosomes, mitochondria, and nuclei to flow from cell to cell.Coenocytic fungi – a fungus that lacks septa. It’s body is made up of a conitnuous cytoplasmic mass that may contain hundreds or thousands of nuclei.
6 Haustoria – modified hyphae on parasitic fungi enabling it to penetrate the cell walls of plants (however, it remains enclosed in the plasma membrane of the plant).Mycorrhizae – mutualistic relationship between plant roots and fungi-- Plant provides fungus with a steady supply of sugar-- Fungus increases the suface area for water uptake and also supplies plant with phosphate and other minerals absrobed from the soil. Fungus also secretes growth factors that stimulate roots to grow and branch and antibiotics that help protect the plant from disease.Ectomycorrhizal Fungi – Forms a dense sheath over the surface of the rootArbuscular mycorrhizal fungi – (aka Endomycorrhizae) – microscopic fungal hyphae extend into the root. Makes extensive contact with the plant through brancing of hyphae that forms arbuscules.
8 ReproductionFungal sporesa. reproduced sexually or asexually (Sexual reproduction only occurs when there has been some change in environment)b. unicellular or multicellularc. produced in specialized hyphal structuresd. carried by wind or watera. contributes to adaptation in changing environment
9 Fungi Sexual Reproduction Heterokaryotic Stage “different nuclei” Dikaryon (n+n)“two nuclei”, one cellPlasmogamyUnion of 2 parent myceliaKaryogamyHaploid nuclei fuse producing a diploid cellMycelium (n)Diploid Stage (2n)Meiosis immediatelyGerminationSporesSpore producing structures (n)(n)
12 How do fungi contribute to an ecosystem? DecomposersSome produce antibioticsFoodYeast (alcohol, bread)Cholesterol lowering drugsHigh blood pressure medicineMolecular genetics research (easy to culture and manipulate)What are some examples of how fungi are important to humans?
13 Diversity of Fungi (4 divisions) 1. Chytridiomycotaa. may be link between fungi and other Eukaryoticsb. mainly aquaticc. decomposers or parasiticd. make uniflagellated spores called zoosporese. coenocytic hyphaef. most primitive
14 2. Zygomycota – “zygote fungi” a. mostly terrestrialb. live in soil or on dead plants and animalsc. major group forms mycorrhizaed. coenocytic – septa only found where reproductive cells are formed.e. common one is black bread mold3. Glomeromycetes (formerly thought to be Zygomycetes)a. Many plants form mycorrhizal associations with this fungi
15 4. Ascomycota – “sac fungi” a. all habitatsb. lichens, mycorrhizae, live on leaves and release toxins to protect plant from insectsc. defining feature – production of sexual spores in saclike asciThis is the sexual stage – dikaryon – seen in macroscopic fruiting bodies called ascocarpsDikaryon hypae give rise to asciKaryogamy takes place withing asciMeiosis produces ascospores (8 in a row) ****Think meiosis lab!!!!!!
16 5. Basidiomycota – “Club Fungi” a. mushrooms, puff ballsb. decomposers, mycorrhizae, parasitesc. long lived dikaryotic myceliumd. reproduces sexually
17 6. Lichensa. Symbiotic association of millions of photosynthetic microorganisms held in a mesh of fungal hyphae.Algae provides fungus with foodFungus gives algae a suitable environment for growth