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