Fungal Traits, Structure, and Diversity

Fungal Traits and Diversity

• Fungi share similarities with plants, possessing cell walls made of chitin and remaining stationary while growing.
• Fungi spread through spores, similar to plant reproduction methods.
• Unlike plants, fungi lack chlorophyll and photosynthesis, obtaining food by breaking down organic matter, mirroring animal behavior.
• Fungi and animals are heterotrophic, relying on external organisms for sustenance.
• Fungi secrete digestive enzymes externally before absorbing nutrients, akin to animal digestion.
• Unlike autotrophic plants, fungi are heterotrophic.
• Plants contain chlorophyll and cellulose, while fungi have chitin in their cell walls.
• Animals are ingestive heterotrophs, whereas fungi are absorptive heterotrophs.

Multi-Celled Fungi Structure

• Multi-celled fungi consist of hyphae, which are tiny threads.
• Hyphae extend into the soil, facilitating nutrient absorption.
• Hyphae have cell walls and membranes.
• Mycelium, a network of hyphae, forms the main fungal body and is the feeding structure for nutrient absorption.

Fungi Nutritional Needs

• Fungi do not produce their own food.
• Fungi act as decomposers, breaking down plants and animals and returning nutrients to the soil.
• Parasitic fungi infect living organisms, causing diseases to acquire nutrients.

Flagellated Fungi (Chytrids)

• Chytrids produce flagellated spores for movement in water.
• Chytrids can be single-celled or form hyphae without cross walls.
• Chytrids function as decomposers and parasites, breaking down organic material and infecting plants and insects.

Zygote Fungi Growth

• Zygote fungi develop hyphae that extend across food sources to absorb nutrients.
• As hyphae spread, they form a mycelium network.
• Some hyphae grow upward, forming spore cases for reproduction.

Zygote Fungi Reproduction

• Fungi grow and reproduce asexually through spore formation (mitosis).
• Two fungi form branches (gametangia) that merge.
• Gametangia fusion creates a young zygospore with two nuclei.
• Nuclear fusion results in a mature diploid zygospore.
• Through meiosis, the zygospore creates haploid sexual spores that develop into new fungi.

Microsporidian Infection

• Microsporidians, parasites, infect insects, fish, and humans.
• Microsporidian spores enter a host's body.
• Spores form a polar tube.
• The polar tube penetrates the host cell, injecting the microsporidian contents.
• Inside the host cell, microsporidia consume nutrients and replicate.
• The infected cell bursts, releasing new spores that target additional cells or hosts.

Glomeromycota Fungi Structure

• Glomeromycetes fungi hyphae spread through soil and plant roots, helping the plant acquire nutrients.
• Fungi grow inside plant root cells, facilitating nutrient exchange.

Sac Fungi Growth Forms

• Tiny, single-celled yeasts grow and reproduce via budding.

Sac Fungi Ascocarp Function

• Asci form inside the ascocarp.
• Within the ascus, two nuclei combine to form a diploid zygote.
• The zygote undergoes meiosis, generating four haploid spores.
• Each spore undergoes mitosis, resulting in eight haploid spores.
• Spores are released, spreading the fungus.

Club Fungi Life Cycle

• Spores are released and initiate hyphal growth.
• Two hyphae fuse, forming a dikaryotic mycelium with two distinct nuclei per cell.
• The mycelium develops a fruiting body.
• Nuclei fuse, creating a diploid zygote within the gills.
• The diploid nucleus undergoes meiosis, generating haploid spores.

Dikaryotic Phase Length

• Club Fungi has the longest dikaryotic phase, potentially lasting for years as the fungus develops.
• Sac fungi dikaryotic phase occurs inside the fruiting body and lasts long enough to produce spores.
• Zygote fungi dikaryotic phase happens briefly within the zygosporangium before nuclei fuse.

Biological Roles of Fungi

• Fungi break down organic waste, releasing nutrients back into the soil for other organisms.
• Fungi form mutualistic relationships, such as mycorrhizal fungi sharing water and nutrients with plant roots.
• Some fungi, like rust and mildew, can infect and harm plants.

Fungal Infections in Humans

• Athlete's foot causes itchy, burning, and cracked skin.
• Yeast infections show white patches with soreness, itching, and redness in the mouth.

Human Uses of Fungi

• Fungi, like saccharomyces, are used for fermentation in wine, beer, and bread production.
• Aspergillus helps produce soy sauce.