Fungi Flashcards
Characteristics of Fungi
→ Eukaryotic
→ Heterotrophic
↪ Extracellular digestion and absorption of nutrients
→ Cell walls made of chitin
→ Most fungi are multi-cellular
→ Reproduce using spores
↪ Both asexual and sexual spores produced
↪ Spores are haploid in chromosome number
→ Fungi bodies made of hyphae
Fungal spores
Spore is a haploid cell that is produced by mitosis from a haploid parent cell. Some develop into new haploid cells without fertilization while other need to be fertilized. When being fertilized, two haploid spores fuse to make a diploid spore called a zygospore. After germination, it undergoes meiosis to create haploid cells that form hyphae.
Hyphae and Mycelium
Hyphae: Thread-like filaments that make up multicellular fungus. The hyphae will begin growth when a spore germinates, forming a new strand of hyphae complete with a new strand of nucleus and organelles.
The cells are separated by septum, a part of the cell wall that allows cellular organs to pass via large pores. They are enclosed by a cell wall made of chitin.
A network of hyphae are called mycelium.
Fungi eating
→ Use extracellular digestion
↪ The tips of the hyphae release enzymes that break down the food
↪ After the food is broken down, the products diffuse back into the hyphae
Fungal Classification
→ Fungi are more related to animals than plants
→ Used to be classified closely with plants
↪ Both contain cell walls but plants have cellulose while fungi have chitin
↪ Plants are autotrophic while fungi are heterotrophic
↪ Plants are vascular with vascular tissue (xylem and phloem) while fungi are not vascular
↪ Mycelium are not the equivalent of roots.
Basidomycota
→ A phyla of fungus
↪ Includes mushrooms
→ Has fruiting bodies (like the mushroom [it is connected to a mycelium network underground but the mushroom itself is the fruiting body]) called the basidia.
Life cycle of Basidiomycota
1) Hyphal fragment breaks off from vegetative mycelium
2) Fragment grow to produce new mycelium via mitosis
3) Vegetative mycelium grows
4) Two hyphae fuse together for sexual reproduction (the nucleus moves into one of the cells)
↪ since the nucleuses don’t fuse, it is has a ploidy of | n + n | and is called dikaryotic
5) Fruiting Structure (like mushroom) develops
6) Now the hyphae fuse together to produce a diploid cell, the mother cell of the basidia
7) Basidiospores form from the young basidia (mother cells)
8) Basidiospores mature and discharge
9) Basidiospore germinate to produce hyphae
Spores don’t really have gender so different gametes are denotes by a plus and minus sign. Different combos can be made for sexual reproduction (+–, —, +++, ++, –, -+-, etc). However the gametes need to be compatible for reproduction to occur.
Why are Fungi important
→ Some fungal species have a close association with the roots of trees
↪ Symbiosis
↪ 80-90% of vascular plants have mycorrhizal partners
↪ Called mycorrhizae
↪ The hyphae from the fungus interact with the roots of the tree
↪ Mutually beneficial relationship
↪ ↪ Plants supply carbon source and energy to fungus
↪ ↪ Fungi supply essential minerals from the soil to the plant
→ The fungi do not reproduce sexually and cannot survive without the plant
→ They are decomposers in major systems
Humans use it for
→ Food (yeast, mushrooms, truffle)
→ Beverage and bread production (yeast)
→ To develop antibiotics/medicine like penicillin
→ Genetic Engineering/Research Applications
Pathogenic Fungi
→ 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
→ Ringworm – fungal infection of the skin
→ Candida albicans is responsible for vaginal yeast infections and for infections of the mouth called thrush
→ Zombie fungus in ants: A fungus that grows inside an ant and controls it before killing it.
→Can also have pathogenic fungi that infect plants, other animals, etc
↪ A fungal species called Chytrid is infecting amphibians
