Overview
This lecture concludes the chapter on microorganism diversity by focusing on fungi, covering their characteristics, reproduction, ecological roles, and importance.
Characteristics of Fungi
- Fungi are eukaryotic organisms distinct from animals, plants, and protists.
- They are heterotrophs, meaning they obtain energy by consuming or decomposing organic matter.
- Fungi act as decomposers, breaking down large molecules into absorbable smaller ones.
- They can be unicellular (like yeast) or multicellular (like mushrooms).
- Fungi are generally immobile and have thread-like structures called hyphae.
- The mycelium is a network of hyphae, typically found below ground.
Reproduction in Fungi
- Fungi reproduce both sexually and asexually.
- Asexual reproduction uses spores, which are haploid cells.
- Sexual reproduction involves the fusion of hyphae from two individuals, resulting in a diploid cell.
- The gills under the mushroom cap contain spores for reproductive dispersal.
- Diploid means having two sets of chromosomes (one from each parent); haploid means one set.
Ecological and Practical Importance
- Fungi play a critical role as decomposers in ecosystems by breaking down cellulose and lignin in plant cell walls.
- They form symbiotic relationships with plant roots called mycorrhizae, which is a mutualistic association.
- Fungi can be beneficial (medicine, food production: e.g., yeast, penicillin) or harmful (pathogens causing disease/spoilage).
- Some fungi cause diseases in humans (athletes foot), crops (tomato blight), and are emerging health threats (e.g., drug-resistant fungi in hospitals).
Key Terms & Definitions
- Eukaryote — Organism whose cells contain a nucleus.
- Heterotroph — Organism that obtains energy by consuming other organisms.
- Autotroph — Organism that makes its own food (e.g., via photosynthesis).
- Hyphae — Threadlike structures forming the body of a fungus.
- Mycelium — The mass of hyphae that makes up the main body of a fungus.
- Spores — Reproductive cells capable of developing into a new organism.
- Haploid — Having a single set of chromosomes.
- Diploid — Having two sets of chromosomes, one from each parent.
- Mycorrhizae — Mutualistic symbiosis between fungi and plant roots.
- Mutualism — Symbiotic relationship where both partners benefit.
Action Items / Next Steps
- Review differences between prokaryotes and eukaryotes.
- Study fungal structure and modes of reproduction.
- Recall examples of fungal benefits and diseases.
- Prepare for questions on symbiotic relationships and fungal ecological roles.