copyright © 2005 pearson education, inc. publishing as benjamin cummings body structure the...

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Body Structure

• The morphology of multicellular fungi

– Enhances ability to absorb nutrients

– Chitin

Hyphae. The mushroom and its

subterranean mycelium are a continuous

network of hyphae.

Reproductive structure.

The mushroom produces

tiny cells called spores.

Spore-producing

structures

20 m

Mycelium

Figure 31.2

Hyphae

Mycellum


Hyphal Structure

• Most are multicellular

– Cells divided by septa

• Some have no cross wall- Coenocytic Figure 31.3


Figure 31.4a, b

haustoria

Hyphal Structure


Nematode Hyphae25 m

(a) Hyphae adapted for trapping and killing prey

Figure 31.4a, b

Hyphal Structure


Mycorrhizae

• Are mutually beneficial relationships between fungi and plant roots

– Mycorrhizae “fungus roots”

• Delivers minerals and receives organic nutrients

– Ectomycorrhizal fungi: Grow in extracellular spaces of roots

– Endomycorrhizal fungi: Hyphae go through cell wall to plasmamembrane


• Mycorrhizae

– Increase plant productivity

RESULTS

Figure 31.21

RESULTS

Fungus-Plant Symbiosis


Malted barley


Saccharomyces cerevisiae


• Brewer's yeast tolerate up to about 5% alcohol. Beyond this alcohol level the yeast cannot continue fermentation. Wine yeast on the other hand tolerates up to about 12% alcohol. The level of alcohol tolerance by yeast varies from 5% to about 21% depending on yeast strain.

• Part 1 Aerobic (Oxygen is present) This is the initial rapid process where the yeast is doubling its colony size every 4 hours. (Usually 24-48 hours)

• Part 2 Anaerobic. (No oxygen present) Slower activity and the yeast focuses on converting sugar to alcohol rather that increasing the number of yeast cells. (This process can take from days to weeks depending on the yeast and the recipe)


• The overall process of fermentation is to convert glucose sugar (C6H12O6) to alcohol (CH3CH2OH) and carbon dioxide gas (CO2). The reactions within the yeast to make this happen are very complex but the overall process is as follows:

• C6H12O6 ====> 2(CH3CH2OH) + 2(CO2) Sugar ====> Alcohol + Carbon dioxide gas (Glucose) (Ethyl alcohol)

• Note: The sugars used can be a range of fermentable sugars. These sugars are converted by enzymes to glucose which is then convered to alcohol and CO2


Diploid phase follows karyogamy

• Short-lived (2n) spore-producing structures and (1n) spores

SporangiaBasidiocarp

Ascocarp


• Concept 31.3: Fungi descended from an aquatic, single-celled, flagellated protist

• Fungi and Animalia as sister kingdoms

• Fungi early colonizers of land, probably as symbionts with plants.


• Concept 31.4: Fungi radiated into a diverse set of lineages


Hyphae

Chytrids

• Found in freshwater and terrestrial habitats

• They can be saprobic or parasitic

• Zoospores: unique with flagellated spores

Figure 31.10


• Fast growing bread and fruit molds

• Can also be parasitic or symbiotic relationship

Zygomycetes


Rhizopusgrowingon bread

Matingtype (+) Mating

type (–)

PLASMOGAMY

Key

Haploid (n)

Heterokaryotic (n + n)

Diploid (2n)

100 µm

SEXUALREPRODUCTION

KARYOGAMY

Zygosporangium(heterokaryotic)

Diploidnuclei

MEIOSIS

Sporangium

Mycelium

Dispersal andgermination

Dispersal andgermination

ASEXUALREPRODUCTION

Sporangia

50 µm

Zygospore

Zygomycetes

Figure 31.13


• Pilobolus “aim” their sporangia toward the light

Zygomycetes

Figure 31.14

http://www.youtube.com/watch?v=9CRNmde0WUc&feature=relatedhttp://www.youtube.com/watch?v=TrKJAojmB1Y


• Pilobolus “aim” their sporangia toward the light

Zygomycetes


Glomeromycetes

• arbuscular mycorrhizae

• See Figure 31.15

http://www.agro-genesis.com/pics/cropscience_rhizogold1.jpg


Ascomycetes


Glomeromycetes

• Spores produced in a saclike asci “sac fungi”

• Asci are within the ascocarp


Basidiomycetes

• Include mushrooms and shelf fungi

• Clublike structure called a basidium


Mushrooms are examples of basidiocarps

Figure 31.20


• Concept 31.5: Fungi have a powerful impact on ecosystems and human welfare


Decomposers

• Essential recycling between the living and nonliving world


Fungus-Animal Symbiosis

• Helping break down plant material

Figure 31.22


Lichens

• Symbiotic association of photosynthetic microorganisms held in fungal hyphae

(a) A fruticose (shrub-like) lichen

(b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichensFigure 31.23a–c


Lichens

• The fungal component

– Is most often an Ascomycete

• Algae or cyanobacteria

– Occupy an inner layer below the lichen surface

Ascocarp of fungus

Fungalhyphae

Algallayer

Soredia

Algal cell

Fungal hyphae

10

m

Figure 31.24


Pathogens

• About 30% of known fungal species

– Are parasites, mostly on or in plants

(a) Corn smut on corn (b) Tar spot fungus on maple leaves (c) Ergots on ryeFigure 31.25a–c


Practical Uses of Fungi

• Make cheeses, alcoholic beverages, and bread

• Genetic research on fungi is leading to applications in biotechnology

• Antibiotics produced by fungi treat bacterial infections


Charophytes

ANCESTRALALGA

Red algae

Chlorophytes

Charophytes

Embryophytes

Virid

iplan

taeStrep

top

hyta

Plan

tae


• 3 billion years terrestrial surface was lifeless

• Now roughly 290,000 living plant species

Overview: The Greening of Earth

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