Fungi – Overview and Structure Study Guide

Introduction:

• Fungi are a kingdom of multicellular eukaryotic organisms that are heterotrophs (cannot make their own food and rely on other sources) and play key roles in nutrient recycling in an ecosystem.
• They are also called eukaryotic fungi.
• Fungi include microorganisms like yeasts, molds, and mushrooms.
• Fungi usually grow in moist and warm places to support them.
• Fungi are heterotrophs.

Examples of Fungi:

• Fungi appear as black spots on bread when left outside for some days,
• Fungi are used in food production like yeast cells in the production of beer and bread
• Consumed in the form of mushrooms
• Fungi occur in most skin infections and other fungal diseases.

Structure of a Fungi:

The structure of fungi can be described as follows.

• Most fungi have a filamentous structure.
• They can be single-cell or multicellular organisms.
• Fungi consist of long thread-like bodies called hyphae. These hyphae form a mesh-like structure called mycelium.
• Fungi have a cell wall that contains chitin and polysaccharides.
• The cell wall is made up of protoplast, which further comprises other cell parts like cell membrane, cytoplasm, cell organelles, and nuclei.
• The nucleus is dense, clear, with chromatin threads, and surrounded by a nuclear membrane

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Characteristics of Fungi

Following are the important characteristics of fungi:

• Fungi are eukaryotic and heterotrophic organisms.
• Fungi are unicellular or filamentous.
• Reproduce using spores.
• Fungi display the phenomenon of alternation of generation.
• Fungi lack chlorophyll and hence cannot perform photosynthesis.
• Fungi store their food in the form of starch.
• Biosynthesis of chitin occurs in fungi.
• The nuclei of the fungi are very small.
• The fungi have no embryonic stage, and they develop from spores.
• They reproduce sexually or asexually.
• Some fungi are parasitic and can infect the host.
• Fungi produce pheromone – the chemical which leads to sexual reproduction in fungi.

Classification of Fungi

Fungi are classified based on different parameters as follows:

1. Mode of nutrition:

Based on nutrition, kingdom fungi can be classified as:

– Saprophytic – The fungi derive nutrition by feeding on dead organic substances. Examples: Rhizopus, Penicillium, and Aspergillus.

– Parasitic – The fungi get their nutrition by living and absorbing nutrients from their host organisms (plants or animals). Examples: Taphrina and Puccinia.

– Symbiotic – These fungi have an interdependent mutually beneficial relationship with other species. Examples: Lichens and mycorrhiza.

2. Spore Formation:

Fungi are classified into the following based on the formation of spores:

– Zygomycetes – The fusion of two different cells forms these.

– Ascomycetes – They are also called sac fungi. They can be coprophilous, decomposers, parasitic or saprophytic.

– Basidiomycetes – Mushrooms are the most commonly found basidiomycetes and mostly live as parasites.

– Deuteromycetes – They are otherwise called imperfect fungi as they do not follow the regular reproduction cycle of the other fungi.

Reproduction in Fungi

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Reproduction in fungi is both by sexual and asexual means. The sexual mode of reproduction is teleomorph, and the asexual mode of reproduction is called an anamorph.

– Vegetative reproduction – happens by budding, fission, and fragmentation. Hyphae are divided into separate cells by end walls, and this division between cells in many fungi is called Septa.

– Asexual reproduction – occurs with the help of spores called conidia, zoospores, sporangiospores.

– Sexual reproduction – is through ascospores, basidiospores, and oospores.

Uses of Fungi

Fungi are one of the most important groups of organisms on the planet. It plays a vital role in the biosphere and has great economic importance for its benefits and harmful effects.

Some of the important uses of fungi are:

1. Recycling – They play a major role in recycling dead and decayed matter.

2. Food – Mushrooms are edible, cultured, and used as food by humans.

3. Medicines – Many fungi are used to produce antibiotics, to control diseases in humans and animals. Penicillin antibiotic is derived from common fungi, Penicillium.

4. Bio-control Agents – Fungi exploit insects and other small worms to control pests. Spores of fungi are used as spray-on crops.

5. Food spoilage – Fungi play a major role in recycling organic material and are responsible for major spoilage and economic losses of stored food.

Common examples of Fungi are:

1. Yeast
2. Mushrooms
3. Molds
4. Truffles

Conclusion:

• Fungus are a kingdom of multicellular eukaryotic organisms that are heterotrophs (cannot make their food) and play key roles in nutrient recycling in an ecosystem.
• Fungi are characterized by its filamentous structure and cellular make up- single-celled or multicellular, cell, nuclei, etc.
• Fungi are broadly classified based on obtaining nutrition and spore formation.
• Reproduction in fungi is both by sexual and asexual means
• Fungi play a vital role in the biosphere and have great economic importance on account of their both benefits and harmful effects

FAQs:

1. What is the structure of fungi?

A typical fungus comprises a mass of branched, tubular filaments enclosed in a rigid cell wall. The filaments (called hyphae) branch into a radially expanding network called the mycelium.

2. What are fungi? Explain in detail?

• Fungi are a family of multicellular eukaryotic organisms. They are heterotrophs (cannot make their food) and play important roles in nutrient recycling in an ecosystem.
• Fungi reproduce both sexually and asexually and have symbiotic associations with plants and bacteria.

3. What are the main structural parts of fungi?

The body of most fungi is made up of fine, branched, and usually colorless threads called hyphae. Vast numbers of these intertwining hyphae make up a tangled web called the mycelium.

4. What are fungi and their characteristics?

Fungi are eukaryotic organisms. Some of their key characteristics include: they are heterotrophs; reproduce sexually or asexually; there is no embryonic stage for fungi, and reproduce using spores.

5. What are the four structures of fungi?

1. Cell wall: This layer around the cell membrane of fungi cells is made largely of chitin and other polysaccharides.
2. Mycelium. A fungal mycelium is a network of thread-like filaments called Hyphae
3. Fruiting Body. The fruiting body of a fungus is a reproductive structure
4. Spores. Spores are involved in fungal reproduction

6. Are fungi heterotrophic or autotrophic?

All fungi are heterotrophic – they extract the energy from other organisms to sustain life. Like animals, fungi extract the energy (such as sugar and protein ) stored in the bonds of organic compounds in living or dead organisms.

7. What do fungi do?

Fungi and bacteria are responsible for breaking down organic matter and releasing carbon, oxygen, nitrogen, and phosphorus into the soil and the atmosphere. Fungi are essential to many household and industrial processes, notable among them being fungi used to make bread, wine, beer, and certain cheeses.Like bacteria, fungi play an essential role in ecosystems by performing the role of decomposers, and they recycle nutrients by breaking down organic matter into simple molecules.

8. Why are fungi important?

Fungi are important for the key role they play in nature. Fungi decompose organic matter and release carbon, oxygen, nitrogen, and phosphorus into the soil and the atmosphere. Fungi are essential to many household and industrial processes, notably the making of bread, wine, beer, and certain cheeses.

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Sources:

1. Fungi https://flexbooks.ck12.org/cbook/ck-12-biology-flexbook-2.0/section/8.8/primary/lesson/fungi-bio/ Accessed on 9 Dec 2021
2. Fungi Structure https://flexbooks.ck12.org/cbook/ck-12-biology-flexbook-2.0/section/8.9/primary/lesson/fungi-structure-bio/ Accessed on 9 Dec 2021
3. Characteristics of Fungi. https://courses.lumenlearning.com/boundless-biology/chapter/characteristics-of-fungi/ Accessed on 9 Dec 2021
4. Fungal Structures. https://www.sciencedirect.com/topics/immunology-and-microbiology/fungal-structures Accessed on 9 Dec 2021
5. Fungus. https://www.britannica.com/science/fungus Accessed on 9 Dec 2021

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