bio stage 2 chapter 4

Fungi

Kingdom of Fungi

Mycota

Thalloid organisms

Lack true roots, stems, or leaves.

Composition of Fungi

Thread-like structures called hyphae that interweave to form a mycelium which constitutes the main body of the fungus

Fungal cell wall composition

chitin, cellulose, and glucans

Saprophytic

A fungi that obtains nutrients from decaying organic matter playing a vital role in decomposition

Parasitic

Fungi that derive nutrients from living hosts often causing diseases in plants, animals, or humans

Symbiotic

Fungi that live in mutually beneficial associations with other organisms, such as mycorrhizae

Obligate Parasitic Fungi

These fungi live parasitically in nature on specific suitable hosts. If the appropriate host is not available, they enter a dormant stage or die

Facultative Parasitic Fungi

These fungi are normally saprophytic in natural conditions but are capable of becoming parasitic under certain circumstances

Obligate Saprophytic Fungi

These fungi live exclusively on decomposing organic matter, whether of plant or animal origin

Facultative Saprophytic Fungi

These fungi are usually parasitic, but when a suitable host is not available, they switch to a saprophytic lifestyle

Symbiotic Fungi

These fungi live in a symbiotic relationship, exchanging mutual benefits with other living organisms

Facultative

Able to function in more than one way depending on environmental conditions

Tinsel Flagella

consist of a long axis with numerous hair-like projections extending along its sides

Whiplash Flagella

Consist of a long basal part and a short, flexible terminal segment (2 micrometer)

Asexual Reproduction in Fungi

Occurs through spores, such as conidia or zoospores in certain aquatic fungi. may also take place through fragmentation or budding

Sexual Reproduction in Fungi

Characterized by the fusion of nuclei (karyogamy) and the formation of specialized reproductive structures, including:

• Zygomycetes → Zygosporangium

• Ascomycetes → Ascus

• Basidiomycetes → Basidium

• Deuteromycetes → No observed sexual stage; parasexuality (e.g. Penicillium, Aspergillus).

Sporangium

a structure that produces and contains spores

Conidial Spores

Non-motile spores that are formed externally on specialized structures

The shape, size, and color vary greatly

They may occur singly or in chains

Sexual Reproduction

Plasmogamy

Karyogamy

Meiosis

Plasmogamy

Also called cellular fusion, it involves the fusion of the cytoplasm between two cells, allowing the nuclei to come close together within the same cell

Karyogamy

In this stage, the haploid nuclei (n) fuse to form a diploid nucleus (2n).

Meiosis

Following karyogamy, the diploid nucleus undergoes meiotic division to produce haploid nuclei, each forming gametangia or spores enclosed by a cell wall and cytoplasm, leading to the formation of sexual spores