Biology 1108

1
Lecture 10

• Biology 1108
• Chapter 31 Fungi

2
Learning Objectives (p. 1 of 2)

• List
• 3 types of fungi using absorptive nutrition
• Explain
• Relationship between plasmogamy, heterokaryotic
  stage, karyogamy

3
Learning Objectives (p. 2 of 2)

• Define
• Exoenzymes
• Saprobic
• Septa
• Chitin
• Coenocytic
• Haustoria

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Eukaryotes

• Fungi closest to animals
• Like all eukaryotes, have nuclei

5
Fungi Nutrition

• Absorption
• Small molecules taken directly from environment
• Use exoenzymes
• Heterotrophic

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Fungi Using Absorptive Nutrition

• Saprobic fungi
• Saprobe decomposer
• Rely upon non-living material for food
• Parasites
• Absorb nutrients from hosts cells
• Mutualistic fungi
• Live as beneficial partners
• Help partner to absorb nutrients (ie plants)

7
Hyphae

• The basic construction unit of all fungi, except
  yeasts
• Thin tubes, surrounding cell membranes and
  cytoplasm

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Mycelium

• A mat formed from hyphae
• The vegetative part of the fungus
• Important in feeding
• One in Oregon is 3.4 miles in diamter
• 2,400 years old

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Septa

• The cross walls inside of hyphae
• Have pores to allow movement of
• Nuclei
• Ribosomes
• Mitochondria

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Chitin

• A polysaccharide w/ nitrogen
• Also found in arthropods (like insects,
  crustaceans)
• Forms cell walls, like cellulose of plants

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Coenocytic Fungi

• Lack septa
• Contrast left and right
• Cytoplasm is continuous
• Many, many nuclei

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Haustoria

• Modifications of the hyphae
• Used by parasitic fungi to penetrate tissues
  rob hosts

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7th Inning Stretch
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Fungal Predation

• Arthrobotrys has modified hyphae in shape of a
  lasso
• Lives in soil
• Captures, penetrates nematode worm digests

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Surface Area to Volume Ratio

• 10 ccs of soil may have
• 1 km of hyphae
• 300 square cm of hyphae surface area
• Key to adding surface area is growing hyphae
  longer, not thicker
• Which holds more sauce ravioli or spaghetti Os?

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Spore

• A tiny haploid cell that can produce a new
  individual
• Produced sexually or asexually
• Often airborne some found 100 miles up!

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Heterokaryon

• A mycelium, having genetically different nuclei
• Formed when two genetically different hyphae
  connect

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Sexual Reproduction

• Plasmogamy
• 1st stage
• Fusion of cytoplasm
• Karyogamy
• 2nd stage
• Fusion of nuclei

19
Heterokaryotic Stage

• Exists between plasmogamy kayrogamy, sometimes
  for centuries