What is Photosynthesis

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WHAT MAKES FUNGI DIFFERENT FROM PLANTS AND
ANIMALS?
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Key Features of Fungi

• Fungal Bodies Consist of Slender Threads
• Fungi Obtain Their Nutrients from Other Organisms
• Fungi Propagate by Spores
• Most Fungi Can Reproduce Both Sexually and
  Asexually

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Be thinking about.

• What Are the Key Features of Fungi?
• What Are the Major Groups of Fungi?
• How Do Fungi Interact with Other Species?
• How Do Fungi Affect Humans?

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TOXIC MOLD
???? chronic bronchitis, learning disabilities,
mental deficiencies, heart problems, cancer,
multiple sclerosis, chronic fatigue, lupus,
fibromyalgia, rheumatoid arthritis, multiple
chemical sensitivity, bleeding lungs ????
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MMOLD IN YOUR KITCHEN
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MUSHROOMS ON YOUR PIZZA
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Without fungus your beer would be flat and
your bread would be really tough
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Fungus in African dust can infect after thousands
of miles of transport by winds
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Fungal Body Structure

• Most fungi are multicellular
• Cells are surrounded by cell walls composed of
  chitin, a nitrogen-containing polysaccharide

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Fungal Body Structure

• Body of almost all fungi is a mycelium, an
  interwoven mass of threadlike filaments called
  hyphae (singular, hypha)

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Fungal Body Structure

• Hyphae of most species are divided into many
  cells by partitions called septa (singular,
  septum) each cell possesses one or more nuclei
• Pores in the septa allow cytoplasm to stream from
  one cell to the next

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Fungal Body Structure

• Hyphae of some fungi lack septa, consisting of
  single elongated cells with hundreds or thousands
  of nuclei
• The nuclei of most species are haploid

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Nutrition and Fungal Lifestyles

• All are heterotrophic
• Secrete enzymes outside their bodies and absorb
  the digested nutrients

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Nutrition and Fungal Lifestyles

• Have diverse lifestyles
• Fungal decomposers (saprobes) feed on dead
  organic material and wastes
• Fungal parasites absorb nutrients from cells of
  living hosts and may cause disease
• Some symbiotic fungi live in mutually beneficial
  relationships with other organisms
• Fungal predators consume living organisms

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Propagate by Spores

• Spores are haploid reproductive cells capable of
  developing into an adult fungus
• Usually produced in large numbers
• Dispersed by animals or air currents

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Fungal Reproduction

• Both asexual and sexual reproduction involve the
  production of spores within fruiting bodies

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Asexual Reproduction

• Typically occurs under stable conditions
• Can occur either by
• Fragmentation of the mycelium
• Asexual spore formation
• Haploid mycelium produces haploid asexual spores
  by mitosis
• Spores germinate and develop into a new mycelium
  by mitosis
• Results in the rapid production of genetically
  identical clones

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Sexual Reproduction

• Typically occurs under conditions of
  environmental change or stress
• Neighboring haploid mycelia of different, but
  compatible mating types come into contact with
  each other
• The two different hyphae fuse so that the nuclei
  share a common cell
• The different haploid nuclei fuse to form a
  diploid zygote
• Zygote undergoes meiosis to form haploid sexual
  spores

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Sexual Reproduction

• Spores germinate and develop into a new mycelium
  by mitosis
• Results in the production of genetically diverse
  fungal bodies

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Section 22.2 Outline

• 22.2 What Are the Major Groups of Fungi?
• Chytrids Produce Swimming Spores
• Zygomycetes Can Reproduce by Forming Diploid
  Spores
• Ascomycetes Form Spores in a Saclike Case
• Basidiomycetes Produce Club-Shaped Reproductive
  Structures
• Some Fungi Form Symbiotic Relationships

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Classification of Fungi

• Fungi have been assigned to four phyla based upon
  the way they produce sexual spores
• Chytridiomycota (chytrids)
• Zygomycota (zygote fungi)
• Ascomycota (sac fungi)
• Basidiomycota (club fungi)

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The Chytrids

• The Chytrids
• Most are aquatic
• Reproduce both asexually and sexually
• Form flagellated spores that require water for
  dispersal
• Figure 22-4, p. 426, illustrates the chytrid
  fungus Allomyces in the midst of sexual
  reproduction

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The Chytrids

• Most feed on dead aquatic material
• Some species are parasites of plants and animals
• One chytrid species is a frog pathogen believed
  to be a major cause of the current worldwide
  die-off of frogs
• Primitive chytrids are believed to have given
  rise to the other groups of modern fungi

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Zygomycetes

• Most live in soil or on decaying plant or animal
  material
• Reproduce both asexually and sexually
• Sexual spores are thick-walled zygospores

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Zygomycetes

• During asexual reproduction
• Haploid spores are produced via mitosis in black
  spore cases called sporangia
• Spores disperse and germinate to form new haploid
  hyphae

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Zygomycetes

• During sexual reproduction
• Two hyphae of different mating types come into
  contact and fuse
• Nuclei fuse to form a diploid zygospore, a tough,
  resistant structure that can remain dormant for
  long periods until conditions are favorable

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Zygomycetes

• During sexual reproduction
• Meiosis occurs as the zygospore germinates
• Resulting spores disperse and germinate to form
  new haploid hyphae that can enter either the
  asexual or sexual cycle

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Ascomycetes

• Live in a variety of marine, freshwater, and
  terrestrial habitats
• Reproduce both asexually and sexually
• Sexual spores form in saclike asci

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Basidiomycetes

• Live in a variety of marine, freshwater, and
  terrestrial habitats
• Usually reproduce sexually
• Sexual spores form in club-shaped basidia
• Figure 22-9, p. 429, depicts an overview of
  sexual reproduction in a basidiomycetes

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Basidiomycetes

• During sexual reproduction
• Two hyphae of different mating types come into
  contact and fuse, resulting in the formation of a
  fruiting body

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Basidiomycetes

• Each fruiting body contains numerous club-shaped
  structures called basidia (singular, basidium)
• Nuclei within each basidium fuse, forming a
  diploid zygote

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Basidiomycetes

• Zygote divides by meiosis producing four
  basidiospores (haploid sexual spores)
• Basidiospores disperse and germinate to form new
  haploid hyphae that enter the sexual cycle
  (asexual reproduction is rare)

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Basidiomycetes

• Better known examples include
• Mushrooms (some are edible, others are poisonous)
• Puffballs
• Shelf fungi (decomposers of wood)
• Stinkhorns
• Rusts and smuts (plant parasites)
• Yeasts

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Fairy Rings

• A fairy ring is a circular pattern of mushroom
  growth
• Fairy rings form at the leading edge of an
  expanding underground fungal mycelium
• The wider the diameter of the ring, the older the
  mycelium
• Some fairy rings are estimated to be 700 years old

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Section 22.3 Outline

• 22.3 How Do Fungi Interact with Other Species?
• Lichens Are Formed by Fungi That Live with
  Photosynthetic Algae or Bacteria
• Mycorrhizae Are Fungi Associated with Plant Roots
• Endophytes Are Fungi That Live Inside Plant Stems
  and Leaves
• Some Fungi Are Important Recyclers

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Symbiotic Relationships

• A symbiosis is a close interaction between
  organisms of different species over an extended
  period of time
• The fungal member of a symbiotic relationship may
  be harmful (a parasite of plants or animals) or
  beneficial (lichens and mycorrhizae)

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Lichens

• Lichens are symbiotic associations between fungi
  (usually an ascomycete) and algae or
  cyanobacteria
• Fungus provides photosynthetic partner with
  shelter and protection
• Photosynthetic partner provides fungus with food
  (sugar)

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Lichens

• Grow on a wide variety of materials (soils, tree
  trunks and branches, rocks, fences, roofs, and
  walls)
• Are able to survive environmental extremes (newly
  formed volcanic islands, deserts)
• Are very diverse in form

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Mycorrhizae

• Mycorrhizae (singular, mycorrhiza) are symbiotic
  associations between fungi and plant roots
• Fungus provides plant with water, minerals, and
  organic nutrients it absorbs from the soil
• Plant provides fungus with food (sugar)

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Endophytes

• Endophytes are fungi that live inside the
  above-ground tissues of plants
• Some are parasites that cause plant diseases
• Some are beneficial to host plants
• Some ascomycete species live inside grasses and
  produce substances that are distasteful or toxic
  to insects and grazing mammals, protecting the
  grasses from predation

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Recyclers

• Fungi are Earths undertakers, feeding on the
  dead of all kingdoms
• Fungal saprophytes (feeding on dead organisms)
  release extracellular substances that digest the
  tissues of the dead and liberate carbon,
  nitrogen, phosphorus compounds, and minerals that
  can be reused by plants

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Section 22.4 Outline

• 22.4 How Do Fungi Affect Humans?
• Fungi Attack Plants That Are Important to People
• Fungi Cause Human Diseases
• Fungi Can Produce Toxins
• Many Antibiotics Are Derived from Fungi
• Fungi Make Important Contributions to Gastronomy
• Fungal Ingenuity

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Fungi Attack Plants

• Fungal parasites cause the majority of plant
  diseases
• Ascomycete parasites cause Dutch elm disease and
  Chestnut blight
• Rusts and smuts are basidiomycete parasites that
  cause considerable damage to grain crops

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Fungi Attack Plants

• Fungi can destroy plant material that has been
  harvested for human use
• Cause wooden structures to rot
• Damage cotton and wool fabrics

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Fungi Attack Plants

• Some fungi benefit agriculture
• Used to control insect pests such as rice
  weevils, tent caterpillars, aphids, citrus mites,
  and grasshoppers
• Fungi identified that attack mosquitoes that
  transmit malaria

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Fungi Cause Human Diseases

• Athletes foot, jock itch, and ringworm are
  caused by fungi that attack the skin
• Valley fever and histoplasmosis are caused by
  fungi that attack the lungs
• Infection occurs when victim inhales spores

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Fungi Cause Human Diseases

• Most vaginal infections are caused by the yeast
  Candida albicans

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Fungi Produce Toxins

• Molds of the genus Aspergillus produce
  aflatoxins, highly toxic, carcinogenic compounds
• Infect foods such as peanuts

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Fungi Produce Toxins

• Claviceps purpurea (an ascomycete) produces
  several toxins
• Infects rye plants and causes ergot disease
• Symptoms of ergot poisoning include
  vasoconstriction of blood vessels, vomiting,
  convulsive twitching, hallucinations, and death

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Fungi Produce Antibiotics

• Penicillin
• First antibiotic to be discovered
• Used to combat bacterial diseases

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Fungi Produce Other Drugs

• Cyclosporin
• Used to suppress the immune response during organ
  transplants

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Fungi Contribute to Gastronomy

• Certain ascomycete molds impart flavor to some of
  the worlds most famous cheeses
• Roquefort
• Camembert
• Stilton
• Gorgonzola

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Fungi Contribute to Gastronomy

• Yeasts are used in the production of wine, beer,
  and bread
• Wine is produced when yeasts ferment fruit
  sugars ethyl alcohol is retained, while CO2 is
  released

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Fungi Contribute to Gastronomy

• Beer is derived when yeasts ferment sugars in
  germinating grains (usually barley) ethyl
  alcohol and CO2 are retained
• Bread rises when yeasts ferment sugar that has
  been added to bread dough both ethyl alcohol and
  CO2 escape during baking

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Fungi Contribute to Gastronomy

• Some fungi are consumed directly
• Mushrooms (a basidiomycete)
• Morels (an ascomycete)
• Truffles (an ascomycete)

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Fungal Ingenuity

• The truffle has evolved an effective adaptation
  for dispersal of its spores
• Releases an odor which causes pigs and other
  animals to dig it up, scattering spores to the
  winds
• The zygomycete Pilobolus has evolved bulb tops
  that blast off, spreading spores

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Fungal Ingenuity

• Arthrobotrys cleverly traps and strangles
  microscopic roundworms called nematodes to obtain
  nutrients

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