lecture 7 Fungi (Morphology, Physiology, Life cycle) Flashcards
Fungi are…
- Eukaryotic organisms
- Nonphotosynthetic
- Nonmotile (except for a small proportion of life
stage)
Morphological characteristic of fungi
- Body Forms:
- Unicellular (yeasts)
- Filamentous structures called hyphae
- Aggregation of hyphae forms mycelium
- Special Structures:
- Sclerotium: hardened mass of mycelium for
overwintering - Multicellular structures like rhizomorphs, fruiting
bodies, and mushrooms
- Sclerotium: hardened mass of mycelium for
Are fungi Autotrophs or Heterotrophs?
Heterotrophs
Heterotrophs
Depend on external sources for nutrients.
what are Saprophytes or Saprobes
Consume dead tissues or organic waste, acting as decomposers.
Symbionts
Engage in mutually beneficial relationships, like mycorrhizal associations.
Parasites
Feed on living tissues of plants or animals.
Pathogens
If the feeding behavior of a parasite causes disease in the host organism.
Heterotrophic Absorption in Fungi
Process:
- Active transport mechanisms are employed for nutrient absorption.
- Hyphae release enzymes that break down substrates like cellulose, lignin, proteins, and lipids.
- Digestion products- disaccharides,
monosaccharides, amino acids, oligopeptides, and small lipid molecules.
- Fungal cells reabsorb these products.
- Food Storage: Glycogen is used to store food materials.
Fungal Hypha
- Tubular structures are interconnected via septums (plural septa)
- Chitin cell wall
- Multinucleate
- Grows through hyphal tip
Fungal Cell Wall - Composition
Chitin: Provides strength and shape, made of N-acetylglucosamine β-1,4 linkage.
β-1,3 Glucans: Extends throughout the cell wall.
Fungal Cell Wall - Outer Layer
Contains N- and O-linked oligosaccharides like mannans associated with glycoproteins.
GPI Anchors: Some glycoproteins use GPI anchors to attach to the plasma membrane or inner wall.
What are the two major types of reproduction in fungi
Asexual Sporulation
Sexual Sporulation
Asexual Sporulation origin
Mitotic origin, involves mycelial fragmentation or direct asexual sporulation.
Asexual Sporulation advantages
Clonal Population
Adapted to Environment
Quicker Dispersal
Less Energy Consuming
Clonal Population
the offspring are genetically identical to the parent.
can be advantageous in maintaining favorable traits within a population.
Sexual Sporulation
Meiotic origin.
More Energetically Costly
Differentiates Major Fungal Groups
Classification Based on Fruiting Bodies (Asci or Basidia)
Sexual Sporulation advantage
Results in Greater Genetic Diversity
Sexual reproduction in fungi
1.Fusion of 2 hyphae with different mating types
2.Exchange of nuclei
3.Dikaryotic phase
4.Fusion of 2 nuclei
5.Diploid zygote
6.Meiosis or Mitosis
7.Production of sexually formed spores
Life cycle of an asexual fungus
Spores
Germination
Mycelium
Spore producing structures
Life cycle of a sexual fungus
Spores
Mycelium
Plasmogamy (fusion of cytoplasm)
Dikaryotic stage
Karyogamy (Fusion of nuclei)
Diploid stage
Meiosis
Spore producing structures
How many fungal phyla are there ?
5
Fungal phyla distinguished by?
Reproductive features
Name the 5 fungal phylum
Chytridiomycota (chytrids)
Zygomycota (Zygote fungi)
Glomeromycota (arbuscular mycorrhizal fungi)
Ascomycota (sac fungi)
Basidiomycota (club fungi)
