Fungi characteristics

Characteristics of Fungi

Fungi are eukaryotic organisms, which means they possess a true nucleus enclosed in membranes. They lack a vascular system, including xylem and phloem. While fungi share the presence of cell walls with plants, animals do not have cell walls. Unlike many organisms, fungi do not go through an embryonic stage.

Reproduction in fungi occurs through the production of spores, which can be sexual or asexual. Sexual spores include oospores, zygospores, ascospores, and basidiospores, while asexual spores include sporangiospores, aplanospores, zoospores, and conidia. Both types of spores can be produced depending on the species and environmental conditions. Fungi are typically non-motile.

Fungi exhibit the phenomenon of alternation of generations, meaning they have both haploid and diploid stages in their life cycle. Fungi are achlorophyllous, lacking the chlorophyll pigments necessary for photosynthesis found in plant cells.

The vegetative body of fungi can be unicellular or composed of microscopic threads called hyphae. These hyphae can grow and interconnect to form a network called a mycelium. Yeasts are unicellular fungi that do not produce hyphae. Fungal cell walls are structurally similar to those of plants but chemically composed of chitin (C8H13O5N)n.

The cell membrane of fungi contains unique sterols and ergosterol. Fungi are heterotrophic organisms, obtaining their food and energy from organic substances, including dead plant and animal matter. They thrive in acidic environments and produce exoenzymes such as hydrolases, lyases, oxidoreductases, and transferases to digest and break down food. Fungi store their food as starch and undergo chitin biosynthesis.

Many fungi have small nuclei with repetitive DNA. During mitosis, the nuclear envelope remains intact. Fungi exhibit diverse nutritional strategies, acting as saprophytes (obtaining energy from dead and decaying matter), parasites (living in a host and causing harm), or symbionts (mutually beneficial relationships).

The optimal temperature for growth varies between saprophytic fungi (20-30°C) and parasitic fungi (30-37°C). Fungal growth rates are generally slower than those of bacteria. Fungal reproduction can occur through both sexual and asexual means. The sexual state is referred to as teleomorph (fruiting body), while the asexual state is referred to as anamorph (mold-like structures).

Reproduction in fungi involves various methods, including fragmentation, somatic budding, fission, asexual spore formation, gametic copulation, gamate-gametangium copulation, gametangium copulation, somatic copulation, and spermatization. Pheromones, chemical substances produced by fungi, play a role in sexual reproduction between male and female fungal cells.

Some fungi are macroscopic and visible to the naked eye, such as molds and mushrooms. It is estimated that there are approximately 1.5 million fungal species on Earth, but only around 300 species are infectious to humans. Examples of human-infecting fungi include Candida albicans, Aspergillus, Blastomyces, Coccidioides, Cryptococcus neoformans, Histoplasma, Pneumocystis jirovecii, and others.

Key Points:

Fungi are eukaryotic organisms with a true nucleus enclosed in membranes.
They lack a vascular system (xylem and phloem) and are non-vascular.
Fungi have cell walls composed of chitin, unlike animals which lack cell walls.
Fungi reproduce through spores, both sexually and asexually.
They exhibit alternation of generations, having both haploid and diploid stages.
Fungi are non-motile and do not possess chlorophyll for photosynthesis.
The vegetative body of fungi can be unicellular or composed of hyphae, which form a mycelium.
Fungal cell walls are chemically composed of chitin.
Fungi are heterotrophic organisms, obtaining food from organic substances.
They produce exoenzymes to digest food and store it as starch.
Fungi thrive in acidic environments and have unique sterols in their cell membranes.
Fungal growth rates are slower than bacteria.
Fungi can reproduce sexually (teleomorph) or asexually (anamorph).
Pheromones play a role in sexual reproduction between fungal cells.
Some fungi are macroscopic (visible to the naked eye) like molds and mushrooms.
There are approximately 1.5 million fungal species on Earth, but only around 300 species are infectious to humans.
Examples of human-infecting fungi include Candida albicans, Aspergillus, Cryptococcus neoformans, and others.