Fungal cells – Erakina

Fungi cell wall is made uo of chitin. They are eukaryotic organisms that are present ubiquitously. One distinct characteristic of fungi in the presence of chitinous cell walls. Fungi are present in abundance all over the world. The most commonly seen forms of fungi are yeasts and molds. Mushrooms are commonly used for culinary purposes. But, there is much more to these tiny organisms than meets the eye. They are morphologically and physiologically distinct from both plants and animals. They are heterotrophic, like animals, and do not photosynthesize like plants. However, they are immobile like plants, and their only means of mobility is via the dispersion of fungal spores. They possess the ability to form both saprophytic and symbiotic relationships with other organisms. They are common commensals as well. Fungi play an important role in the process of nutrient cycling as they decompose dead organic matter and reduce it to absorbable nutrient forms in the soil, thus allowing the uptake of these nutrients by plants, thereby continuing the cycle. Fungi and algae, for instance, have a special symbiotic relationship that includes the fungi providing protection and water to the algae while the algae synthesise food for the fungi as these organisms lack chlorophyll and cannot synthesise their food. This relationship between fungi and algae is observed in the form of lichens.

Fungi and their morphology

Most fungi have very distinct morphological characteristics, which include the following-

• Presence of fungal hyphae, which are thread-like structures.
• Hyphae can form a large network and result in the formation of mycelium.
• Septate hyphae are compartmentalised, with each compartment having one or two nuclei along with cell organelles.
• Coenocytic fungi do not possess compartmentalised hyphae.
• Fungal colonies usually exhibit a multitude of shapes and colours.
• Some fungal species form an apothecium, which is a reproductive fruit body and is commonly seen in mushrooms.

Fungi and their physiology

Fungi are very metabolically versatile and have mastered the art of utilizing the simplest nutrient sources. They are heterotrophic, and hence their growth and physiology are such that they have evolved to assist them in the process of using the carbon fixed by other organisms.

• Fungal hyphae, efficiently invade solid substrates and absorb nutrients readily due to their relatively large surface areas.
• Fungal cells produce and secrete hydrolytic enzymes that allow the breakdown of organic matter such as proteins, lipids, and carbohydrates into simpler units.
• Fungi also exhibit radiotrophic growth, which can be defined as the utilisation of energy from radiation with the help of pigments (for example: melanin).

Fungal cells and their characteristics

As mentioned before, commonly found fungi are usually present in the form of hyphae, yeast cells or moulds. Hyphae cannot be defined as cells, in a conventional sense but, in a way, can be classified as a “supracellular state”. This is due to the continuity of hyphal compartments as the septae contain spores that allow the transportation of nutrients and cell organelles between compartments, Coenocytic fungi do not have any sort of separation and, hence,is  just one long thread-like structure.

Yeast cells are vegetative and reproduce via the process of budding, unlike hyphal cells that reproduce via the production of reproductive spores. Yeast cells are oval or round in shape and form cellular protrusions known as buds. 

Fungal cell wall

Some of the important characteristics of the fungal cell wall are as follows-

• The cell wall is made up of a network of glucans, chitins, and other polysaccharides.
• It helps to maintain cell turgor and pressure.
• It provides structural integrity to the fungal cell.
• It provides a surface for the dynamic interaction between the fungal cell and its surrounding environment.
• Fungal cell walls recognise chemical signals, which enable fungi to react to the environment.

Fungal cytoskeleton

The fungal cytoskeleton is made up of the following components-

• Microtubules
• Actin filaments
• Septins

It should be noted that a dense and complex network of these components results in the formation of fungal spindles during nuclear division, provides structural integrity to the cell, and also allows intracellular communication.

Fungi are very versatile organisms that play a major role in our lives. Yeast is used commercially for the process of fermentation and is an integral part of the brewery and baking industries. Mushrooms provide several medicinal properties and are also a source of nutrition. Fungal cells have very distinct structures, and certain technical aspects in the context of cell structure vary across different fungal species. Fungi are cryptic organisms because they are ubiquitously present, yet they are still unambiguous.