Approximately, there are 100,000 known species of fungi which are different by fungi structure, their shapes, characteristics and there resemblance or difference with plants and animals. Fungi include many different types of organism.
- Some fungi are pathogens like rust, smut of wheat and corn. Molds grow on important crops and foodstuff.
- There are some delicious fungi like truffles and morels.
- There are commercial uses of some fungi like Pencillium is a source of antibiotics penicillin. Yeasts are used in bakeries and breweries.
- Fungi act as decomposer like bacteria.
Taxonomic Position of Fungi
Fungi were placed earlier in the plant kingdom. Later, they were separated from the plant kingdom and were given the status of a separate kingdom Fungi.
Fungi show following resemblances with the plants:
- Both have cell wall.
- Both lack centrioles.
- Both are non-motile.
Difference form plants
- Fungi are heterotrophic, whereas plants are autotrophic.
- The cell wall of fungi is composed of chitin, while the cell wall of plants is composed of cellulose.
Resemblances with animals
Fungi resemble more with the animals than the plants. They show following resemblances with the animals.
- Fungi are heterotrophs like animals, while plants are autotrophs.
- The cell wall of fungi is composed of chitin. Chitin is also present in the external skeleton of arthropods. While the cell wall of plants is composed of cellulose.
Due to these similarities, some mycologists (scientists who study fungi) think that fungi and animal have a common ancestor.
Differences from the Animals
Fungi have following differences from the animals:
- Fungi have cell wall but absent in animals
- Fungi are absorptive heterotrophs (they absorb food while animals ingest .ood) .
- Fungi are non-motile.
Some Special Characters of Fungi
Fungi are neither plants nor animals, as they show some special characters:
- The DNA studies of fungi have confirmed that fungi are different form all other organisms.
- Fungi show characteristic type of mitosis, called nuclear mitosis. In this case nuclear envelop (nuclear membrane) does not break during mitosis; the mitotic spindle is formed within the nucleus. The nuclear membrane constricts between the two clusters of daughter chromosomes and divides the nucleus. In some fungi nuclear envelope disappears late.
Above discussion shows that the fungi are distinct organism form the plants, animals and protists. So they are given the status of a separate kingdom called kingdom “Fungi”.
The Body of Fungus
The body of a fungus is called mycelium. It is composed of hyphae. Yeast is non-hyphal unicellular fungi.
Hyphae in Fungi Structure
The long, slender, branched tubular thread like filament is called hyphae (singular hypha). Hyphae spread over the surface of substratum. Their cell wall contains chitin. Chitin is resistant to decay. There are two types of hyphae:
- Septate hyphae: Septate hyphae are divided by cross walls, called septa (singular septum) into individual cells. Each hypha contains one or more nuclei. The septa of many septate fungi have pores. The cytoplasm can flow through these pores. It carries material to the growing tips of the hypha. So the hyphae grow rapidly when food and water are abundant and temperature is favorable.
- Non-Septate hyphae: They lack septa and hyphae are not divided into individual cells. They form an elongated multinucleated large cell. Such multinucleate hyphae are called coenocytic hyphae. Its cytoplasm moves effectively and distributes the material throughout the hyphae.
Growth of Hyphae
The hyphae grow rapidly when food and water are abundant and temperature is favorable. The parts of fungus growing through the substrate are metabolically active. These hyphae form extensive spreading system of hyphae. It increases the surface area for absorption.
Reproductive Fungi Structures
Hyphae may pack together and organize to form complex reproductive structures like mushrooms, puff balls, morels etc. These structures expand rapidly. All nuclei of fungi are haploid except diploid zygote. This zygote is formed during sexual reproduction.
The World’s Largest Organism
A single mycelium may produce upto a kilometer of new hyphae in only one day. Fungi Armillaria may be called world’s largest organism. It is a pathogenic fungus. It afflicts conifers. It grows out of central focus. It spreads upto 15 hectares (hectare = 10000 m2).
Characters of Fungi
- Fungi are special living organisms, have simple body, called “mycelium”.
- Fungi do not contain chlorophyll so they are not able to manufacture its own food material. They are either parasite or saprophyte.
- Their cell wall is made up of Chitin & Fungal cellulose.
- They either cause diseases in plants & animals or destroy foodstuff.
- Some fungi are useful & may be used as food, such as lush rooms. The mushrooms are of different type and some mushrooms are poisonous.
- In Fungi reproduction takes place by asexual or sexual method.
- From fungi Penicillin and other antibiotics are obtained.
- The body of fungi is very simple known as mycelium. It consists of many thread like or fiber like structures known as Hyphae.
- Inside the mycelium cytoplasm, nuclei and oil globules are present globules store food material.
- Mycelium are of three types:
- Septate mycelium (Hyphae) septa — cross wall. In chis are divided by cross wall so the myceliurn internally divided into many cells. Each cell contains one nucleus (Primary) two nuclei (Secondary) hyphae.
- Aseptate mycelium (Hyphae) A = not, septa = cross wall. In this type, hyphae septa are not present so the hyphae are not divided into individual cells. It is also known as coenocytic hyphae (multi nucleate condition with common cytoplasm).
- Septate with perforation in many septate fungi have a pore through which cytoplasm flows from cell to cell.