Body Structure The morphology of multicellular fungi Enhances ability to absorb nutrients Chitin Reproductive structure. The mushroom produces tiny cells called spores. Hyphae. The mushroom and its subterranean mycelium are a continuous network of hyphae. Hyphal Structure Most are multicellular Cells divided by septa Some have no cross wall- Coenocytic Figure 31.3 Hyphae Spore-producing structures 20 µm Figure 31.2 Mycelium Mycellum Hyphal Structure Hyphal Structure Nematode Hyphae 25 µm haustoria (a) Hyphae adapted for trapping and killing prey Figure 31.4a, b Figure 31.4a, b Mycorrhizae Are mutually beneficial relationships between fungi and plant roots Mycorrhizae fungus roots Fungus-Plant Symbiosis Mycorrhizae Increase plant productivity Delivers minerals and receives organic nutrients Ectomycorrhizal fungi: Grow in extracellular spaces of roots RESULTS Endomycorrhizal fungi: Hyphae go through cell wall to plasmamembrane Figure 31.21
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 Ascocarp Sporangia Basidiocarp Concept 31.3: Fungi descended from an aquatic, single-celled, flagellated protist Concept 31.4: Fungi radiated into a diverse set of lineages Fungi and Animalia as sister kingdoms Fungi early colonizers of land, probably as symbionts with plants. Chytrids Found in freshwater and terrestrial habitats They can be saprobic or parasitic Fast growing bread and fruit molds Can also be parasitic or symbiotic relationship Zoospores: unique with flagellated spores Hyphae Figure 31.10
Key Haploid (n) Heterokaryotic (n + n) Diploid (2n) Rhizopus growing on bread Pilobolus aim their sporangia toward the light PLASMOGAMY Mating type (+) Mating type ( ) 100 µm SEXUAL REPRODUCTION Dispersal and germination Sporangia KARYOGAMY Sporangium ASEXUAL REPRODUCTION MEIOSIS Zygosporangium (heterokaryotic) Diploid nuclei Zygospore Dispersal and germination Figure 31.13 50 µm Mycelium Figure 31.14 Glomeromycetes Pilobolus aim their sporangia toward the light 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 Mushrooms are examples of basidiocarps Include mushrooms and shelf fungi Clublike structure called a basidium Figure 31.20 Concept 31.5: Fungi have a powerful impact on ecosystems and human welfare Decomposers Fungus-Animal Symbiosis Essential recycling between the living and nonliving world Helping break down plant material Figure 31.22
Lichens Lichens Symbiotic association of photosynthetic microorganisms held in fungal hyphae The fungal component Is most often an Ascomycete Ascocarp of fungus Algae or cyanobacteria Fungal hyphae Algal layer Occupy an inner layer below the lichen surface Soredia (a) A fruticose (shrub-like) lichen Algal cell Fungal hyphae Figure 31.24 10 µm Figure 31.23a c (b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichens Pathogens About 30% of known fungal species Are parasites, mostly on or in plants 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 Figure 31.25a c (a) Corn smut on corn (b) Tar spot fungus on maple leaves (c) Ergots on rye Charophytes Overview: The Greening of Earth 3 billion years terrestrial surface was lifeless Red algae Now roughly 290,000 living plant species ANCESTRAL ALGA Chlorophytes Charophytes Embryophytes Plantae Streptophyta Viridiplantae