Sugaprabha Prasath

Being a microscopic organism, fungi have a complex cellular organization like a membrane-bound nucleus where the DNA is wrapped around histone proteins and so they are considered eukaryotic organisms.

Like plants, fungi have a cell wall but it is made up of chitin and they do not possess chloroplasts. In contrast, their DNA matches the maximum with animals. Prokaryotic organisms have a simple or basic and unorganized Morphology. Fungi have a complex intracellular structural organization and thus they are considered eukaryotic organisms.

Why fungi is eukaryotic?

There are certain criteria by which an organism is considered a eukaryotic organism.

These criteria are that the cells must possess a nucleus and all other organelles should be enclosed/ embedded inside the plasma membrane or cell membrane.

Organelles are nothing but the other functional internal structures that take up various other responsibilities like the synthesis of proteins, production of energy etc.

Fungal cells have a layer outside their nucleus. The contents present inside the cell are guarded by a plasma membrane or cell membrane.

Is fungi prokaryotic or eukaryotic? — Is Fungi Prokaryotic Or Eukaryotic
Image credits- Pixabay free images

Ray fungi is prokaryotic or eukaryotic?

Ray fungi represent the characteristic features of both fungi as well as bacteria.

Ray fungi have another name called Actinomycetes, which is actually a bacteria, not fungi and so they are prokaryotic organisms.

Ray fungi give rise to filamentous narrow hyphae (tube-like structures that aid in the transportation of nutrients) thus making it look like fungus.

Fungi eukaryotic characteristics:

Fungi are eukaryotic organisms and possess a true membranous nucleus.
Fungi do not have vascular systems.
Fungi reproduction.
No embryonic stage in fungi is found.
Fungi are immotile.
Fungi have both diploid and haploid stages.
Fungi are achlorophyllous.
No photosynthesis takes place in fungi.
Hyphae make up the fungi.
Yeasts are single-celled organisms in which no hyphae are produced.
The fungal cell wall is consist of chitin.
Fungi can change their structure based on their environment.

Fungi are eukaryotic organisms and possess a true membranous nucleus.

As discussed earlier, fungi have a complex cellular organization with a complete nucleus that is embedded inside a membrane.

Thus fungi are eukaryotic organisms and possess a true membranous nucleus.

They consist of mitochondria (the powerhouse of the cell), and other networks of inner membranes such as Golgi bodies, endoplasmic reticulum.

Fungi do not have vascular systems.

Fungi do not possess a vascular system so they are non-vascular organisms.

The xylem and phloem is absent.

Fungi reproduction.

Fungi reproduce with the aid of spores such as zygospores, ascospores, oospores, basidiospores, sporangiospores, zoospores, conidiospores, aplanospores.

The spores get dispersed in the air or travel on any animal’s coat.

In comparison to the plant seed, fungal spores are much lighter and very small.

No embryonic stage in fungi is found.

Fungi lack the embryonic stage and they directly produce spores for the reproduction process.

Fungi are immotile

Fungi are immotile organisms that are they cannot able to move because they lack flagella which is a chief component for locomotion.

Fungi have both diploid and haploid stages.

The diploid stage begins with the fusion of the zygote. Haploid halts by nuclear fusion

Haploid+ Haploid= Diploid

Fungi are achlorophyllous.

Fungi are closely associated with plants, but plants have chlorophyll in them which gives a bright green color to plants.

Whereas fungi lack chlorophyll that is they are achlorophyllous organisms but potentially are seen in bright red to green to black in certain species.

No photosynthesis takes place in fungi.

As they don’t have chlorophyll, which is the key ingredient for photosynthesis.

Fungi do not take place in the process of photosynthesis.

Hyphae make up the fungi

The vegetative body of the fungi are mostly unicellular or made up of minute microscopic filaments called hyphae.

Hyphae produce a network or a system that is collectively called mycelium.

Hyphae→ Mycelium → Fungi

Yeasts are single-celled organisms

Yeast is unicellular fungi in which no hyphae are produced.

The single organism is considered as a whole organism.

The fungal cell wall is consist of chitin.

The fungal cell wall is similar to that of plants. In the case of plants, the cell wall is made up of hemicellulose, pectin and cellulose. fungal cells are surrounded by a strong, unbreakable cell wall and also they make up a complicated poly-saccharides component such as chitin. Glucan is also found. But cellulose is not present.

Chitin found in the fungi gives primary solidarity to the cell wall.

The fungal cell wall shields or protects the cell from drying up or desiccation that is moisture removal and protects from other fungal eaters. Flagella are seen in a few types like Chytridiomycota.

Fungi can change their structure based on their environment

The structural body of the fungi is called the thallus which may be single-celled or multi-celled. Certain types of fungi are dimorphic that is they get transformed from single-celled to multi-cell based on the condition they thrive in.

Examples of unicellular fungi: yeast (Saccharomyces cerevisiae), Candida species.

A variety of fungi are multi-cellular (two or more cells present) organisms. They have 2 morphological levels: vegetative morphological level and reproductive level.
The vegetative stage is the collective structure of filaments called the hyphae. Hyphae make up a network or a system which is known or called mycelium.

The reproductive phase differs from one fungus to another.

Also Read:

The purple sulphur bacteria photosynthesis is achievable by using sulphur, hydrogen, hydrogen sulphide as the electron sources in anoxygenic conditions.

The purple sulfur bacteria are anaerobic organisms. They use sulfur from hydrogen sulphide and other organic matter in anoxygenic conditions. They take up sulfur by oxidation and converts it into granules of sulphur and then sulphuric acid is formed.

Now, where does this purple sulfur bacteria photosynthesis process take place? The answer is, the photosynthesis process in purple sulfur bacteria happens in the cell membrane of the bacteria where the active conjugated pigments are present. To be more precise, the stacks and vesicle pigments in the cell membrane is the location where the photosynthesis takes place. These sulfur granules inside the bacterial cell can be clearly visualized under a 1000X microscope.

The purple sulfur bacteria are found mostly in stagnant water, hot springs where there is high sulfur content. This type of bacteria grows really well in sulfur-rich spots.

The purple sulphur bacteria are Gram-negative, non-spore forming bacteria that belong to the group of anaerobic proteobacteria ( can not tolerate oxygen even in minimal amount) but few are microaerophilic (requires little amount of oxygen) that have the ability to perform photosynthesis. These bacteria are categorized into two groups: the Chromatiaceae and the Ectothiorhodospiraceae.

The reason behind the name “PURPLE” “SULFUR” Bacteria is because of the colour that is seen. These bacteria are seen purple to pink. This is because of the presence of carotenoids in the bacterial chlorophyll. The bacterial chlorophyll produces a pigment. This pigmented element in their structure gives the purple bacteria a predominant purple colour to them. When the bacterial colonies occur in many numbers, purple to pink colour surface or water is observed even in naked eyes.

The Ecological contribution of Purple sulfur bacteria is that they play a vital role in fixing that atmospheric carbon, they leave out excess light in the form of heat energy.

As they use hydrogen sulfide for sulfur and methane is taken up as a source of carbon, they play a predominant role in bioremediation as well, as they decrease the toxicity and odour of the water.

Examples: Nitrosococcus sp.

What is Sulphur based photosynthesis?

Most photosynthetic organisms use the oxygen in the water molecule as the electron source. But there are certain anaerobic organisms that can not tolerate oxygen, but still perform the photosynthesis process. Now how do they achieve this?

These organisms use sulfur as their source of electrons for this process. This is called sulphur based photosynthesis and is also known as anoxygenic photosynthesis (no oxygen is involved).

What do sulfur bacteria use as a source of electrons in photosynthesis?

They use sulfur, hydrogen, hydrogen sulphide and other organic matter as electron sources.

How do purple sulfur bacteria carry out photosynthesis?

The Purple sulfur bacteria carry out a photosynthetic process by the bacteriochlorophyll (BChl a and BChl b )pair, P870 absorbs light (photon) at an infrared region 700 nm to 1000 nm and donates an electron to the bacteriopheophytin.

This electron is then transferred to a sequence of electron carriers i.e Quinone- ubiquinone and menaquinone, cytochrome bc complex and finally the electron chain takes place.

During this process, a Proton motor force (PMF) is produced which will later produce ATP (Adenosine triphosphate). The electrons are reserved and can be reused. The Adenosine triphosphate produced is the energy molecule that is finally generated.

purple sulfur bacteria photosynthesis — ***Purple sulfur bacteria- Anoxygenic photosynthesis.***

The transfer of electrons and the photosynthetic reaction centres are present in the cell membrane in the photosynthetic reaction unit.

The photosynthetic unit is made up of light-harvesting or collecting complexes (LHI & LHII) and the reaction centre is where the separation of charges takes place. LHI has more bacteriophylls (present in the photosynthetic unit) and has an absorption of a maximum of 870 nm when compared to LHII.LHII has fewer bacteriophylls, lower maximum absorption which is seen at 850 nm and does not occur in all purple bacteria.

These light-harvesting complexes ( LHI and LHII) are present in the intra- cytoplasmic membrane (where the presence of vesicle sacs, tubules or the stacked lamellar sheets are present). They have increased surface area for better light (photon) absorption. The transfer of energy is performed by the light-harvesting complexes to the reaction centre.

These are the central membrane proteins that have α- and β- apoproteins monomers. Each of these membrane proteins then binds non covalently to the bacteriochlorophyll and carotenoids.

Purple sulfur bacteria photosynthesis equation:

6 CO₂ + 12 H₂S → (CH₂O)_n+ 6 H₂O +12 S

Carbon dioxide + hydrogen sulfide → simple sugars + water+Sulfur (Anoxic condition)

The purple sulfur bacteria take the carbon dioxide and oxidize the hydrogen sulfide ( which produces a rotten egg odour), it produces simple sugar molecules, water and sulfur.

Are purple non Sulphur bacteria photosynthetic?

Yes, Purple non-sulfur bacteria are also photosynthetic organisms.

The purple non-sulfur bacteria can be photoheterotrophs ( organisms that produce energy with the help of light but they can not use carbon dioxide as primary C (carbon) source), photoautotrophs (The organisms that use light. carbon dioxide and can make their own food with the aid of photosynthesis process), chemoheterotrophs( The organisms that get energy by chemical substances and also consume different other organisms to grow).

These bacteria have the tendency to shift their nutritional requirement based on the availability and many other factors like; level of anaerobiosis( how low is the oxygen level), Carbon source and light availability.

The purple non-sulfur bacteria can not use sulfur from hydrogen sulfide or any other sulfur sources as the electron donor for the carbon dioxide reduction. Hence, it is known as purple non-sulfur bacteria and also high sulfur content is toxic for this group of bacteria.

Now here arises a question,

Which is the electron source in purple non-sulfur bacteria?

Hydrogen is their electron donor whereas a lower amount of sulfur is tolerated by the bacteria. In higher concentrations, the bacteria can not thrive in that atmosphere.

Examples of purple non-sulfur bacteria: Rhodopseudomonas, Rhodospirillum.

Do purple sulphur bacteria have chlorophyll:

No, the purple sulfur bacteria do not have chlorophyll.

Instead, they have a major light-collecting pigment called bacteriochlorophyll (BChla & BChlb) that aids in photosynthesis.

This bacteriochlorophyll strongly absorbs light in the infrared region (700 nm to 1000 nm), thus initiating the photosynthesis process.

Do purple and green sulfur bacteria get their energy from oxygenic photosynthesis?

No, As Purple and Green sulfur bacteria are anaerobic organisms (cannot thrive in an oxygenated environment) or in some cases are microaerophilic (that can tolerate only a little oxygen) organisms, oxygenic photosynthesis is definitely not possible.

How does photosynthesis in green and purple bacteria differ?

Green bacteria absorb longer wavelengths than purple bacteria which absorb shorter wavelengths of light.

Green sulfur bacteria have extracellular sulfur deposits, Gas vesicles, Chlorosomes and bacteriochlorophylls a,c,d or e whereas Purple sulfur bacteria has intracellular sulfur deposits, bacteriochlorophylls a or b only.

The purple sulfur bacteria do not possess gas vesicles or chlorosomes.

What is the function of the Calvin cycle in purple bacteria

Purple bacteria photosynthesis is similar to photosystem I (As they can not use water molecules, Photosystem II is not possible).

The oxidation of hydrogen sulphide through elemental sulfur to sulfate is done by the Calvin cycle.

The role of the Calvin cycle in purple bacteria is also to trap carbon dioxide during the process.

Where does the Calvin cycle of photosynthesis occur in purple bacteria?

Chromatophore is the location where the photosynthesis pigment of present and the photosynthesis takes place.

Chromatophore is an element in bacteria and other certain organisms which produce distinctive colour by absorbing the wavelength.

What is the mode of reproduction in purple sulfur bacteria?

In order to survive, every organism has to reproduce. The mode of reproduction in bacteria is Asexual reproduction and the purple sulfur bacteria also undergoes asexual reproduction.

The type of asexual reproduction is Binary fission in which a single purple sulfur bacterium divides itself into two daughter cells and multiplication or the replication process goes on.

Other facts related to Purple sulfur bacteria:

As they play a vital role in the bioremediation process (Environmental clean up using live microorganisms), researchers have now gained interest in growing this bacteria in natural (lakes and ponds with high sulfur content) or artificial media ( laboratory) to know more about their mechanisms and make it a better element for mankind in bioremediation as physical remediation, chemical remediation requires a load of man work and usage of harsh chemical which is not eco-friendly and not pocket friendly. When a biologic element is used it becomes eco-friendly and also pocket friendly and the post-remediation process is not as tedious as physical and chemical one.