Chapter 29-Fungi
29.1 Why Do Biologists Study Fungi?
ï Fungi can cause debilitating diseases in humans
and crop plants
ï Fungi nourish the plants that nourish us
ï They affect climate change because they are
critical to the carbon cycle on land
Fungi Have Important Economic and Ecological
Impacts
ï species of fungi cause human illness:
ï This incidence is low compared to other
organisms
ï Fungi cause destructive impact on our food supply:
ï Rusts, smuts, mildews, wilts, and blights cause
billions of dollars of crop losses each year
ï Saprophytic fungi are responsible for losses due
to spoilage
ï Fungi have many positive impacts:
ï They are the source for many antibiotics (ex.
penicillin)
ï Mushrooms are eaten in many cultures
ï Yeast is used to make bread, cheese, soy sauce,
beer, wine, and other foods
ï Fungi ferment cacao seeds to make chocolate
edible
ï Fungal enzymes improve characteristics of
foods such as fruit juice, candy, and meat
Mycorrhizal Fungi Provide Nutrients for Land
,Plants
ï Mycorrhizal fungi live in close association with plant
roots
ï Such fungi along those roots are called mycorrhizae
ï Does plant growth suffer if mycorrhizal fungi are
absent?
Saprophytic Fungi Accelerate the Carbon Cycle
on Land
ï Saprophytes are fungi that digest dead plant
material
ï Fungi help cycle carbons through terrestrial
systems
ï The carbon cycle on land has two basic
components:
1. Fixation of carbon by land plants
2. Release of C O2 from cellular respiration
29.2 How Do Biologists Study Fungi?
ï 000 species of fungi have been described and
named:
ï Hundreds more are discovered each year
ï many as 6 million species of fungi may be found
worldwide:
ï ne study, over 650 fungal species were found in
guts of 27 beetle species:
ç these species had never been described
, Analyzing Morphological Traits
ï Fungi have very simple bodies
ï Two growth forms exist:
1. Single-celled formsÑyeasts
2. Multicellular, filamentous formsÑmycelia
(singular: mycelium)
Ð Some species adopt both forms
The Nature of the Fungal Mycelium
ï All mycelia are dynamic:
ï They constantly grow in the direction of food
sources and die back in areas where food is
running out
ï The body shape of a fungus can change almost
continuously throughout its life
The Nature of Hyphae
ï HyphaeÑthe long, narrow filaments of mycelium
ï Filaments are divided into cells by septa (cross-
walls):
ï Pores allow materials to flow between
compartments
ï Some fungi are coenocytic, meaning they lack
septa:
ï Many nuclei are scattered throughout the
mycelium
ï Nutrients can move rapidly through septa pores or
through coenocytic fungi from uptake to growth
areas
29.1 Why Do Biologists Study Fungi?
ï Fungi can cause debilitating diseases in humans
and crop plants
ï Fungi nourish the plants that nourish us
ï They affect climate change because they are
critical to the carbon cycle on land
Fungi Have Important Economic and Ecological
Impacts
ï species of fungi cause human illness:
ï This incidence is low compared to other
organisms
ï Fungi cause destructive impact on our food supply:
ï Rusts, smuts, mildews, wilts, and blights cause
billions of dollars of crop losses each year
ï Saprophytic fungi are responsible for losses due
to spoilage
ï Fungi have many positive impacts:
ï They are the source for many antibiotics (ex.
penicillin)
ï Mushrooms are eaten in many cultures
ï Yeast is used to make bread, cheese, soy sauce,
beer, wine, and other foods
ï Fungi ferment cacao seeds to make chocolate
edible
ï Fungal enzymes improve characteristics of
foods such as fruit juice, candy, and meat
Mycorrhizal Fungi Provide Nutrients for Land
,Plants
ï Mycorrhizal fungi live in close association with plant
roots
ï Such fungi along those roots are called mycorrhizae
ï Does plant growth suffer if mycorrhizal fungi are
absent?
Saprophytic Fungi Accelerate the Carbon Cycle
on Land
ï Saprophytes are fungi that digest dead plant
material
ï Fungi help cycle carbons through terrestrial
systems
ï The carbon cycle on land has two basic
components:
1. Fixation of carbon by land plants
2. Release of C O2 from cellular respiration
29.2 How Do Biologists Study Fungi?
ï 000 species of fungi have been described and
named:
ï Hundreds more are discovered each year
ï many as 6 million species of fungi may be found
worldwide:
ï ne study, over 650 fungal species were found in
guts of 27 beetle species:
ç these species had never been described
, Analyzing Morphological Traits
ï Fungi have very simple bodies
ï Two growth forms exist:
1. Single-celled formsÑyeasts
2. Multicellular, filamentous formsÑmycelia
(singular: mycelium)
Ð Some species adopt both forms
The Nature of the Fungal Mycelium
ï All mycelia are dynamic:
ï They constantly grow in the direction of food
sources and die back in areas where food is
running out
ï The body shape of a fungus can change almost
continuously throughout its life
The Nature of Hyphae
ï HyphaeÑthe long, narrow filaments of mycelium
ï Filaments are divided into cells by septa (cross-
walls):
ï Pores allow materials to flow between
compartments
ï Some fungi are coenocytic, meaning they lack
septa:
ï Many nuclei are scattered throughout the
mycelium
ï Nutrients can move rapidly through septa pores or
through coenocytic fungi from uptake to growth
areas
