21.4 - Fungi

Fungi and You Believe it or not, fungi play an important role in your life. The bread you eat, the salad you make, and the medicine that you take when you are sick may include various types of fungi or products made from fungi. 1. List as many examples of fungi that you can. 2. How are fungi helpful to humans? 3. How are fungi harmful to humans?

What Are Fungi? Types: mushrooms, mold, yeast, mildew, truffles Basic characteristics: Heterotrophic eukaryotes Many feed by absorbing nutrients from decaying matter Others live as parasites absorb nutrients from their hosts

What Are Fungi? Cell walls made of chitin (polymer of modified sugars, also found in arthropod exoskeletons) Evidence that fungi are more closely related to animals than plants Instead of photosynthesis, fungi produce enzymes that digest food outside their bodies, then absorb the small molecules released by the enzymes

Structure and Function yeasts – single-celled  mushrooms - multi-celled hyphae - long, slender branching filaments mycelium - mass of branching hyphae below the soil mushroom fruiting body – reproductive structure that grows above soil clusters of mushrooms are often part of the same mycelium -> same organism

Reproduction Asexually – release spores that travel through air/water or break off a hypha Sexually – transfer of nuclei and cytoplasm from one hypha to another, then create spores

Diversity of Fungi more than 100,000 species of fungi major groups differ in their reproductive structures

The Ecology of Fungi Decomposition champions help ecosystems by breaking down dead organisms/recycling essential elements and nutrients Parasitic fungi cause serious diseases in plants and animals Mutualistic associations with photosynthetic organisms in which both partners benefit

Decomposition Organisms remove important trace elements and nutrients from the soil Fungi release digestive enzymes that break down leaves, fruit, and other organic material into simple molecules Fungi then recycles these elements and nutrients If not returned, the soil would quickly be depleted

Parasitism Plant Diseases Parasitic fungi cause diseases that threaten food crops ex: mildews infect a wide variety of plants ex: corn smut destroys corn kernels

Parasitism Animal Diseases Infect insects, frogs, and mammals - ex: Cordyceps fungus infects grasshoppers in rain forests in Costa Rica Grasshopper eats spores, germinate and produce enzymes that slowly digest all cells and tissues until the insect dies, hyphae develop on dead grasshopper and produce more spores spreading the infection

Human Diseases Ex: athlete’s foot forms a mycelium in the outer layers of the skin, which produces a red, inflamed sore from which the spores can easily spread from person to person Ex: yeast Candida albicans responsible for vaginal yeast infections and for infections of the mouth called thrush

Symbiotic Mutualism Lichens - mutualistic association between fungus + photosynthetic organism - Photosynthetic organism - green alga/ cyanobacterium Algae photosynthesize  source of energy Fungus  provides water and minerals

The Lichen is created between the fungus and the alga                               Mr. Fungus is ready to greet our friend the alga                               Friend alga cell is prepared to greet Mr. Fungus.                                                                                                 The Lichen is created between the fungus and the alga. Friend alga cell is prepared to greet Mr. Fungus Mr. Fungus is ready to greet our friend the alga The Lichen is created between the fungus and the alga

Lichen = Fungus + photosynthetic organism

Symbiotic Mutualism Mycorrhizae – mutualistic relationships between fungus + plant roots - Essential for plant growth Fungi hyphae collect water/minerals and bring them to the roots, also release enzymes that free nutrients in the soil Plants provide fungi w/ the products of photosynthesis (oxygen and sugar)