Fungi

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Fungi

• Biology
• Chapter 20
• Pg. 526 - 547

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21-1 The Kingdom Fungi
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What are Fungi?

• Fungi are eukaryotic heterotrophs that have cell
  walls
• Cell wall is composed of chitin
• Digest food outside of their bodies and then
  absorb it
• Many fungi feed on decaying matter in the soil
  but others are parasites

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Structure and Function of Fungi

• Hyphae
• Basic structural unit of fungi
• Threadlike filaments developed from fungal spores
• Elongated at the tip and branch off to form
  mycelium
• Anchor the fungi to the food source

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• Fungus Structure
• Mycelium
• The bodies of multicellular fungi are composed of
  many hyphae tangled together into a thick mass
• Fruiting body
• The recognized structure of a mushroom (cap)
• reproductive structure

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Reproduction of Fungi

• Most fungi reproduce both asexually and sexually
• Asexual
• Budding - Yeast
• Fragmentation - they get cut up
• Spores produced in structures called sporangia
• Sexual
• Hyphae develop positive and negative ends that
  combine together and then undergo meiosis to make
  new spores that can develope into new fungi

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21-2 Classification of Fungi
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The Common Molds

• Zygomycete have life cycle that include a
  zygospore.
• Decomposers
• Most common bread mold
• Rhizoids
• Hyphae that grow penetrate into the food source
• Rhizoids secrete the chemicals that digest food
• Stolons
• Hyphae that grow horizontally across the surface
  of the food source

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• Asexual reproduction
• Produce sporangia that form and release the
  haploid spores
• Sexual reproduction
• Positive mating strain combines with negative
  mating strain
• Fuse together to form a zygospore that is dormant
  until germinations when it undergoes meiosis to
  form a sporangium and release haploid spores

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The Sac Fungi

• Phylum Ascomycota
• Largest phylum of fungi
• Conidia
• Clusters of asexual spores and are carried by
  conidiophores
• Ascus
• Sack-like structure within the fruiting body that
  carries the sexual spores called the ascospores
• Examples
• Morels, truffles and yeast

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The Club Fungi

• Phylum Basidiomycota
• Mushrooms, puffballs, stinkhorns and bracket
  fungi
• Have club shaped hyphae called basidia that form
  on the gills of the cap
• Spores are called basidiospores and are on
  visible reproductive structures
• Most have only sexual reproduction

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The Imperfect Fungi

• Phylum Deuteromycotes
• Commonly found on fruit
• Only reproduce asexually
• Example
• Penicillinm notatum that is commonly found on
  oranges and produces the antibiotic penicillin
• Ringworm, athletes foot

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21-3 Ecology of Fungi
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All Fungi Are Heterotrophs

• 3 types based on how they obtain food
• Saprophytes (saprobes)
• Mutualists
• Parasites

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Fungi as Decomposers

• Saprophytes (saprobes)
• Decomposers, break down dead organisms
• Essential role in maintaining equilibrium in
  nearly every ecosystem

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Fungi as Parasites

• Parasitic fungi
• Cause serious plant and animal diseases.
• Few cause diseases in humans
• Plant diseases
• Wheat rust caused by basidiomycete
• Human diseases
• Athletes foot caused by deuteromycete
• Other Animal diseases
• Cordyceps lodge in grasshoppers and germinate and
  penetrate the grasshopper and slowly digest it

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Symbiotic Relationship

• Lichens
• Mutualistic relationship between fungi and
  photosynthetic algae or cyanobacteria

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Symbiotic Relationships

• Mycorrhizae
• Live in mutualistic relationships with plants
• Basidiomycotes are the most common

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Adaptations of Fungi

• Decomposers that break down organic materials
• Heterotrophs that use extracellular digestion
• Send chemicals outside to break down the food and
  then absorb the nutrients
• Haustoria
• Specialized hyphae used to penetrate into a host
  cell