Transcript Fungi2
FUNGI Wow! Fungi plant growth - The Private Life of Plants - David Attenborough - BBC wildlife - YouTube Fungi • non-motile • heterotrophs • defining characteristic of fungi is mode of getting food: “extracellular digestion and absorption” • secrete digestive enzymes into the environment, then absorb the nutrients released by those enzymes. • most are decomposers: live on decaying organisms. • some are parasites: extract food from living organisms Kingdom Fungi • fungi were once members of the plant kingdom • some similarities include: • cells are eukaryotic (true nucleus with many organelles). • most are stationary, anchored in the soil • reproduction can be asexual, sexual or both. • However, fungi have evolved in a different direction than plants: Plants Fungi Have one nucleus per cell Often have many nuclei per cell autotrophs (have chlorophyll) heterotrophs Starch is the main storage molecule Have few or no storage molecules Most have roots No roots Cellulose in cell walls Chitin in cell walls (like insects) Most reproduce by seed None reproduce by seed Fungi Structure & Function made of hyphae: tiny threads of cytoplasm surrounded by plasma membrane & covered by cell wall cell walls made of chitin (same as insect shells) hyphae interwoven to creately mycelium: mesh of microscopic branching hyphae that are usually on or just below the surface of the ground. the visible parts (stem and cap)of the fungi are the fruiting body (reproductive parts) Fungal Feeding vast network of mycelium underground form mycorrhizae forms a symbiotic relationship with plant roots gains sugars, starches, protiens and lipids from plant roots provides plant with extension of root to get water and minerals Fungi Reproduction reproduce asexually when a piece of the hyphae breaks off or by releasing spores. spores are haploid cells (have a single set of chromosomes) spores are able to withstand unfavourable conditions and are carried by wind to germinate in other locations. fungi can also reproduce sexually when opposite haploid hyphae grow towards each other and fuse to form a diploid zygospore (which has 2 sets of chromosomes). Planet Wild - Fungi - YouTube Negative Roles of Fungus: • crop parasites (corn smut) – fungi cause a lot of damage to crops each year • foot fungus – athletes foot caused by Trichyphyton sp • chytrid – killing frogs •Frogs: The Thin Green Line - Video: Full Episode - Amphibian Extinction - Chytrid Fungus | Nature | PBS Positive Roles of Fungus: • decomposers (or recyclers) of nutrients in ecosystems. • vital component of many foods (blue cheese, mushrooms, baking and brewing (yeast). • antibiotics (penicillin) • Lichens act as air quality monitors by absorbing toxins in the soil and the air. Yeast Major Phyla of Fungi Phylum Reproductive Structure Examples Zygomycota Zygospores that contain sexual spores Black bread mold Club-shaped cell (basidium) contains sexual spores Mushrooms, puffballs, shelf fungi Sacs called asci that contain sexual spores Yeasts, truffles, morels Fungi with flagellated spores chytrids (common molds) Basidiomycota (club fungi) Ascomycota (sac fungi) Chytrids Pilobolus Zygomycetes • Zygomycetes form a diploid spore (think “zygote”) that undergoes meiosis after germination. Zygomycetes also have asexual, haploid spores. • Bread mold is a common zygomycete • Another important zygomycete group is the mycchorrhyzae, fungi that infect the roots of most plants. These fungi have a symbiotic relationship with the plants: the fungi gather nutrients form the soil as an extension of the roots, and the plant supplies nutrients from photosynthesis. Basidomycetes: Club Fungi • Mushrooms are the most common club fungi. Others include rusts and smuts that harm crop plants. • The visible mushroom is merely a fruiting body. The bulk of the organism is underground, a mat of hyphae (strands) called a mycellium that can be quite large. One example in Oregon covers 2200 acres (3 ½ square miles), to a depth of 3 feet, and it is at least 2400 years old. Ascomycetes • Ascomycetes are sac fungi: they produce spores in sacs. • Truffles and morels are good examples of ascomycetes: they taste good! • Penicillium, the mold that gave penicillin, the first antibiotic, is an ascomycete. Pennicillium also gives flavor to certain cheeses. • Sac fungi also include some important single celled yeasts. Saccharomyces cerevesiae is used to make bread rise and also to ferment beer and wine. Candida albicans produces the common human yeast infections. Zygomycota Chytrid Basidiomycota Ascomycota