Kingdom Fungi

Chapter 22

Characteristics of Fungi

All fungi share 3 characteristics: Fungi have threadlike bodies Fungal cell walls contain chitin

CHITIN – a tough carbohydrate that is found in the hard outer covering of insects and other organisms

Fungi are heterotrophic

Body Structure Fungi have bodies made of threadlike

strands called HYPHAE. Hyphae form a tangled mass often

many meters long called a MYCELIUM.

In some fungi, hyphae also form root-like structures called RHIZOIDS

Obtaining Nutrients Fungi release enzymes that break down

organic and inorganic matter into nutrients. Fungi absorb the nutrients across their

cell walls. SAPROBES – fungi that absorb nutrients

from dead organisms PARASITES – fungi that absorb nutrients

from living hosts

Reproduction Most fungi reproduce sexually and asexually

In SEXUAL reproduction, spores are produced by meiosis Allows for genetic diversity Specialized structures (like mushrooms) for

sexual reproduction In ASEXUAL reproduction, spores are produced by

mitosis Allows for rapid reproduction

Fungi that do not have an observed sexual stage are grouped together and called IMPERFECT FUNGI

Reproduction

Yeast and Mold The words “yeast” and “mold”

refer to SPECIFIC STAGES of the life cycle that are shared by several types of fungi

YEAST Common name for fungi that

exist in a unicellular stage Reproduce asexually by budding

MOLD The rapidly growing, asexually

reproducing stage of some types of fungi

Groups of Fungi Chytrids (Family CHTRIDIOMYCOTA)

A group of aquatic fungi that provide clues about the evolution of fungi

Mostly unicellular saprobes that feed on protists, plants, animals, and other fungi

Common parasites of aquarium fish

Believed to have been the cause of the decline in amphibians in the wild

Groups of Fungi (cont.) Zygote Fungi (Family ZYGOMYCOTA)

Named for sexual reproductive structures that produce zygotes inside a tough capsule (called a ZYGOSPORANGIUM)

Asexual reproduction by spores is most common in zygote fungi

Example: RHIZOPUS – bread mold; can also live in soil

Groups of Fungi (cont.) Sac Fungi (Family ASCOMYCOTA)

ASCUS – a sac-like reproductive structure that produces spores

Usually reproduce asexually Asexual spores called

CONIDIA form by mitosis on specialized hyphae called CONIDOPHORES

Groups of Fungi (cont.) Club Fungi (Family BASIDIOMYCOTA)

Include mushrooms, toadstools, puffballs, jelly fungi, shelf fungi, rusts, and smuts

BASIDIUM – a club-like sexual reproductive structure that produces spores

Sexual reproduction is most common – usually form rings Basidiocarp – reproductive

structure (the “actual” mushroom)

Fungal Partnerships Fungi form mutualistic symbiotic

associations to form lichens and mycorrhizae

LICHEN An association between

fungus and a photosynthetic partner such as cyanobacteria or algae

MYCORRHIZA An association between

fungi and the roots of nearly all plants

Fungi and Industry, Ecosystem, and Disease

(cont.) Fungi are used for food, medicines,

research, alternative fuels, and pest control. FOOD: mushrooms; blue cheese; yeast in

baking, brewing, and winemaking; produce citric acid found in soft drinks and candy

MEDICINES: produce antibiotics like penicillin; bread mold makes cortisone (used to treat skin irritations); yeast has been used to make vaccines for Hepatitis B

ALTERNATIVE FUELS: yeast produce gasohol (gasoline alternative)

FUNGAL INSECT PESTICIDES: reduces the need for harmful/toxic pesticides on crops

Fungi and Industry, Ecosystem, and Disease

Fungi play important ecological roles by decomposing organic matter and by breaking down and absorbing minerals from rocks and soil.

Fungi cause disease by absorbing nutrients from host tissues and by producing toxins. Fungi can grow on and inside tissues of the body

and therefore can be difficult to cure DERMATOPHYTES – fungi that infect the skin and

nails(ex: Athlete’s Foot, Toenail Fungus, and Ringworm) Yeast Infections – occur on reproductive organs and

mouth Toxins produced by fungi can cause vomiting,

diarrhea, liver damage, cancer, and even death