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Are paramecium consumers, producers, or decomposers? 

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Are paramecium consumers, producers, or decomposers? 

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What is a Paramecium? A paramecium is a unicellular (one cell) eukaryotic organism generally found in stagnant water. While very small, sometimes large paramecium can be seen as tin…

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Image Credit: Kateryna Kon / Shutterstock

Life in space is of interest to scientists because on Earth, microbes are sometimes the only living organisms found in extreme conditions such as very high or low temperatures, high salt concentrations, high levels of radiation, or limited nutrients in the environment.

It is expected that for an organism to exist in space, it needs to be able to survive extremely harsh conditions, therefore, microbes seem to be the most likely candidate.

Abundance of microbes

Microbes show a great amount of flexibility in terms of the conditions they can tolerate, and this can be demonstrated by the ability of microbes to continue to perform regular biological functions in these environments.

For example, proteins and DNA are likely to be damaged if conditions change dramatically; therefore, specially evolved mechanisms are needed if the microbe is to survive.

Certain microbes are able to live in harsh environments because their metabolism is adapted for these conditions, therefore they are able to grow and do not have to have special mechanisms in place to survive.

Microbes can tolerate environmental changes through various mechanisms: certain species of microbes can shut down their metabolism and form a resilient "spore", while others make compounds that help to protect the microbe from harsh conditions.

Another way to survive is through a mechanism that allows a microorganism to repair the damage that has been caused by the change in environmental conditions. These mechanisms can ensure the survival of the microbes for a short time, or even for long periods of time.

What happens to microbes in space conditions?

Some existing laboratories have the capability to simulate certain space conditions, for example creating a vacuum and varying temperatures.

However, it is not possible to simulate the amount of UV radiation that would be expected in space, because there are no sources able to emit in the "extraterrestrial UV radiation spectrum".

Several studies focused on using Mars simulation facilities showed that the acidophilic bacterium Acidithiobacillus ferrooxidans was able to grow in Mars-like geochemical conditions, without needing nutrients added to the minerals in the simulated Martian soil.

In fact, the layer of Martian minerals appeared to provide a protective function. More detailed research will hopefully reveal more about the ability of microbes to survive in Martian soil.

Another way to study how microbes are affected by space is using facilities in Low Earth Orbit (LEO).One study to use one of these facilities, the "ADAPT" study, used a strain of the bacterium Bacillus subtilis that had been exposed to increasing UV until it developed resistance to a high level of UV radiation.

Spores of this UV resistant B. subtilis were then sent into the LEO facility. After a year and a half, the research found that if the B. subtilis spores were shielded from radiations in space, then 8% were able to survive in LEO, while all B. sublitis spores survived simulated Mars conditions.

Do humans bring microbes into space?

Humans carry a high number and large variety of microbes, termed the microbiome or microbiota. These microbes associated with humans are connected to the processes within the human body.

What this means is that we all carry a "cloud" of microbes with us, which will therefore be present in spacecraft. Therefore, the microbes found on the International Space Station (ISS) are of interest, both for the health of the crew and for the integrity of the ISS.

Research found that the bacterium Salmonella enterica showed increased virulence in a mouse infection model when grown in space conditions.

In this study, S. enterica was grown on earth as well as aboard a space shuttle. This showed that the activity of 167 genes were different depending on the conditions, which resulted in 73 proteins showing a difference in their expression - i.e. there was greater or lesser protein expression in one condition compared to the other. One of the genes was Hfq, which is the regulator that was behind the changes observed.

What does the future hold for Astro Microbiology?

In order to be able to discover life in space, continued investigation of the limits of life on earth is necessary so that habitable environments in space can be identified.

This would involve exposing microbes found on earth to conditions of space, and importantly exposing them to various conditions at the same time; for this, it would be necessary to take microbes up into space.

Further Reading

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Image Credit: Kateryna Kon / Shutterstock Life in space is of interest to scientists because on Earth, microbes are sometimes the only living organisms found in extreme conditions such as very high or low temperatures, high salt concentrations, high levels of radiation, or limited nutrients in the environment.

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These scientists used a colored dye to make the paramecium easier to see

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These scientists used a colored dye to make the paramecium easier to see

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Paramecium are single-celled organisms that belong to the Ciliophora phylum. Members of this group are characterized by having cilia, or little hair-like structures covering their surface. Once called “slipper animalcules” due to their oblong shape, Paramecium live in a variety of watery environment…

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Perhaps you've heard of -- or even read -- the children's book " Everyone Poops". This illustrative tome explains that because everyone eats, everyone poops. Truer words, as they say, were never spoken. But this is no less true for you than for single-celled organisms like Paramecium.

The creatures in the following film are members of Paramecium caudatum, one of the species of microbial predators I blogged about last week that was capable of eating the spores of the frog-killing fungus Batrachochytrium dendrobatidis -- and one of the two species actually collected from the lakes under study. I came across this video while researching that post and thought it was interesting enough to share with you.

In the video, you can see Paramecium both pooping and peeing, although the peeing analogy is perhaps less apt because the primary function of what you will see is not nitrogen excretion. More on that in a minute. First, filmstrip time.

Here's a quick rundown of what you just saw: at :12 is a great closeup shot; note the flickering cilia -- short beating hairs that power the cell -- at the edges of the cells, particularly at the left tip of the cell in the center.

:35 is the beginning of dramatic pooping scene. If we are lucky, this is the ultimate fate of many a nasty, frog-seeking chytrid spore. Watch the upper right corner of the Paramecium for slow movement toward the exterior. The most exciting action happens at about :45.

Finally, at :51 you see a special star-burst shaped organelle called the contractile vacuole in action. Notice how the radiating collecting tubes dump their contents into the central vacuole one by one. I wonder, do they have pressure-sensitive doors that pop open once the water inside reaches a certain volume? You and I have nothing like this structure in our bodies. What is it doing for this microbe?

As you'll recall from high school biology, single-celled organisms have a fundamental problem created by freshwater: the inside of their body is saltier than the outside, so osmosis will tend to try and stuff water inside. Unchecked, they would explode like balloons. So they need the microbial equivalent of a sump pump to constantly shove that water back outside.

In Paramecium, the solution(!) to this problem is the contractile vacuole, a starburst-shaped organ that collects water and periodically pumps it outside. Recent experiments on Paramecium suggest it does this by actively pumping ions into the vacuole to make the inside saltier still than the rest of the cell's contents. Water flows in the same way it flows into the cell, then gets squeezed mechanically out.

This isn't quite the same thing as urination, though -- it's more like wateration. True urination is about getting rid of nitrogen (your nitrogen waste is excreted in the form of the urea in your urine; fish excrete ammonia, which requires plenty of water to safely dispose, and reptiles and birds excrete uric acid -- that white pasty stuff that lands on your car -- which requires least water of all), and in the process of doing their job, contractile vacuoles no doubt do excrete some nitrogen waste.

But, since Paramecium is a single celled-organism, nitrogen waste can also simply leave by diffusing across the cell membrane, conveniently located not too far from any given point in its body. So this Paramecium is peeing ... sort of. On the other hand, you could also argue that for these organisms, excess water is just as toxic as excess nitrogen is to us, and so the analogy is perfectly apt. Whether you are a human, a whale, or a Paramecium, we all must heed nature's call.

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Perhaps you've heard of -- or even read -- the children's book " Everyone Poops". This illustrative tome explains that because everyone eats, everyone poops. Truer words, as they say, were never spoken. But this is no less true for you than for single-celled organisms like Paramecium.

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Games are a significant and defining part of human culture, and their utility beyond pure entertainment has been demonstrated with so-called 'serious games'. Biotechnology - despite its recent advancements - has had no impact on gaming yet. Here we propose the concept of 'biotic games', i.e., games that operate on biological processes. Utilizing a variety of biological processes we designed and tested a collection of games: 'Enlightenment', 'Ciliaball', 'PAC-mecium', 'Microbash', 'Biotic Pinball', 'POND PONG', 'PolymerRace', and 'The Prisoner's Smellemma'. We found that biotic games exhibit unique features compared to existing game modalities, such as utilizing biological noise, providing a real-life experience rather than virtual reality, and integrating the chemical senses into play. Analogous to video games, biotic games could have significant conceptual and cost-reducing effects on biotechnology and eventually healthcare; enable volunteers to participate in crowd-sourcing to support medical research; and educate society at large to support personal medical decisions and the public discourse on bio-related issues.

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Design, engineering and utility of biotic games

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Games are a significant and defining part of human culture, and their utility beyond pure entertainment has been demonstrated with so-called 'serious games'. Biotechnology - despite its recent advancements - has had no impact on gaming yet. Here we propose the concept of 'biotic games', i.e., games that oper

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Quizmoz - Paramecium Quiz, Paramecium Facts Quiz

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Take the Paramecium Quiz and discover some interesting facts about the slipper-shaped ciliate which is found in oxygenated aquatic environments.

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While single-celled paramecia have the ability to respond to certain external stimuli, they appear not to use that sensory system for simple navigation, new research finds. The work suggests that the ability of paramecia to navigate around flat surfaces is entirely governed by Newton’s Third Law of…

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Read the 1st page and quiz yourself on the 2nd page

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Paramecium ( PARR-ə-MEE-sh(ee-)əm, -⁠see-əm; also spelled Paramoecium) is a genus of eukaryotic, unicellular ciliates, commonly studied as a representative of the ciliate group. Paramecia are widespread in freshwater, brackish, and marine environments and are often very abundant in stagnant basins and ponds. Because some species are readily cultivated and easily induced to conjugate and divide, it has been widely used in classrooms and laboratories to study biological processes. Its usefulness as a model organism has caused one ciliate researcher to characterize it as the " white rat" of the phylum Ciliophora.

Paramecia were among the first ciliates to be seen by microscopists, in the late 17th century. They were probably known to the Dutch pioneer of protozoology, Antonie van Leeuwenhoek, and were clearly described by his contemporary Christiaan Huygens in a letter of 1678. The earliest known illustration of a Paramecium was published anonymously in Philosophical Transactions of the Royal Society, in 1703.

In 1718, the French mathematics teacher and microscopist Louis Joblot published a description and illustration of a microscopic poisson (fish), which he discovered in an infusion of oak bark in water. Joblot gave this creature the name "Chausson", or "slipper", and the phrase "slipper animalcule" remained in use as a colloquial epithet for Paramecium, throughout the 18th and 19th centuries.

The name "Paramecium" - constructed from the Greek ( paramēkēs, "oblong") - was coined in 1752 by the English microscopist John Hill, who applied the name generally to "Animalcules which have no visible limbs or tails, and are of an irregularly oblong figure". In 1773, O. F. Müller, the first researcher to place the genus within the Linnaean system of taxonomy, adopted the name Paramecium, but changed the spelling to Paramœcium. C. G. Ehrenberg, in a major study of the infusoria published in 1838, restored Hill's original spelling for the genus name, and most researchers have followed his lead.

Species of Paramecium range in size from 50 to 330 micrometres (0.0020 to 0.0130 in) in length. Cells are typically ovoid, elongate, foot- or cigar-shaped.

The body of the cell is enclosed by a stiff but elastic structure called the pellicle. This consists of the outer cell membrane (plasma membrane), a layer of flattened membrane-bound sacs called alveoli, and an inner membrane called the epiplasm. The pellicle is not smooth, but textured with hexagonal or rectangular depressions. Each of these polygons is perforated by a central aperture through which a single cilium projects. Between the alveolar sacs of the pellicle, most species of Paramecium have closely spaced spindle-shaped trichocysts, explosive organelles that discharge thin, non-toxic filaments, often used for defensive purposes.

Typically, an anal pore (cytoproct) is located on the ventral surface, in the posterior half of the cell. In all species, there is a deep oral groove running from the anterior of the cell to its midpoint. This is lined with inconspicuous cilia which beat continuously, drawing food inside the cell. Paramecia live mainly by heterotrophy, feeding on bacteria and other small organisms. A few species are mixotrophs, deriving some nutrients from endosymbiotic algae ( chlorella) carried in the cytoplasm of the cell.

Osmoregulation is carried out by contractile vacuoles, which actively expel water from the cell to compensate for fluid absorbed by osmosis from its surroundings. The number of contractile vacuoles varies from one, to many, depending on species.

A Paramecium propels itself by whiplash movements of the cilia, which are arranged in tightly spaced rows around the outside of the body. The beat of each cilium has two phases: a fast "effective stroke", during which the cilium is relatively stiff, followed by a slow "recovery stroke", during which the cilium curls loosely to one side and sweeps forward in a counter-clockwise fashion. The densely arrayed cilia move in a coordinated fashion, with waves of activity moving across the "ciliary carpet", creating an effect sometimes likened to that of the wind blowing across a field of grain.

The Paramecium spirals through the water as it progresses. When it happens to encounter an obstacle, the "effective stroke" of its cilia is reversed and the organism swims backward for a brief time, before resuming its forward progress. This is called the avoidance reaction. If it runs into the solid object again, it repeats this process, until it can get past the object.

It has been calculated that a Paramecium expends more than half of its energy in propelling itself through the water. This ciliary method of locomotion has been found to be less than 1% efficient. This low percentage is nevertheless close to the maximum theoretical efficiency that can be achieved by an organism equipped with cilia as short as those of the members of Paramecium.

Paramecia feed on microorganisms like bacteria, algae, and yeasts. To gather food, the Paramecium makes movements with cilia to sweep prey organisms, along with some water, through the oral groove (vestibulum, or vestibule), and into the cell. The food passes from the cilia-lined oral groove into a narrower structure known as the buccal cavity (gullet). From there, food particles pass through a small opening called the cytostome, or cell mouth, and move into the interior of the cell. As food enters the cell, it is gathered into food vacuoles, which are periodically closed off and released into the cytoplasm, where they begin circulating through the cell body by the streaming movement of the cell contents, a process called cyclosis or cytoplasmic streaming. As a food vacuole moves along, enzymes from the cytoplasm enter it, to digest the contents. As enzymatic digestion proceeds, the vacuole contents become more acidic. Within five minutes of a vacuole's formation, pH of its contents drops from 7 to 3. As digested nutrients pass into the cytoplasm, the vacuole shrinks. When the vacuole, with its fully digested contents, reaches the anal pore, it ruptures, expelling its waste contents to the environment, outside the cell.

Some species of Paramecium form mutualistic relationships with other organisms. Paramecium bursaria and Paramecium chlorelligerum harbour endosymbiotic green algae, from which they derive nutrients and a degree of protection from predators such as Didinium nasutum. Numerous bacterial endosymbionts have been identified in species of Paramecium. Some intracellular bacteria, known as Kappa particles, give Paramecia that have them the ability to kill other strains of Paramecium that lack Kappa.

The genome of the species Paramecium tetraurelia has been sequenced, providing evidence for three whole- genome duplications.

In some ciliates, like Stylonychia and Paramecium, only UGA is decoded as a stop codon, while UAG and UAA are reassigned as sense codons (that is, codons that code for standard amino acids), coding for the amino acid glutamic acid.

The question of whether Paramecia exhibit learning has been the object of a great deal of experimentation, yielding equivocal results. However, a study published in 2006 seems to show that Paramecium caudatum may be trained, through the application of a 6.5 volt electric current, to discriminate between brightness levels. This experiment has been cited as a possible instance of cell memory, or epigenetic learning in organisms with no nervous system.

Reproduction

Like all ciliates, Paramecium has a dual nuclear apparatus, consisting of a polyploid macronucleus, and one or more diploid micronuclei. The macronucleus controls non-reproductive cell functions, expressing the genes needed for daily functioning. The micronucleus is the generative, or germline nucleus, containing the genetic material that is passed along from one generation to the next.

Paramecium reproduction is asexual, by binary fission, which has been characterized as "the sole mode of reproduction in ciliates" ( conjugation being a sexual phenomenon, not directly resulting in increase of numbers). During fission, the macronucleus splits by a type of amitosis, and the micronuclei undergo mitosis. The cell then divides transversally, and each new cell obtains a copy of the micronucleus and the macronucleus.

Fission may occur spontaneously, in the course of the vegetative cell cycle. Under certain conditions, it may be preceded by self-fertilization ( autogamy), or it may immediately follow conjugation, in which Paramecia of compatible mating types fuse temporarily and exchange genetic material.

Conjugation

In ciliates such as Paramecium, conjugation is a sexual phenomenon that results in genetic recombination and nuclear reorganization within the cell. During conjugation, two Paramecia of a compatible mating type come together and a bridge forms between their cytoplasms. Their respective micronuclei undergo meiosis, and haploid micronuclei are exchanged over the bridge. Following conjugation, the cells separate. The old macronuclei are destroyed, and both post-conjugants form new macronuclei, by amplification of DNA in their micronuclei. Conjugation is followed by one or more "exconjugant divisions".

Stages of conjugation

In Paramecium caudatum, the stages of conjugation are as follows (see diagram at right):

1. Compatible mating strains meet and partly fuse

2. The micronuclei undergo meiosis, producing four haploid micronuclei per cell.

3. Three of these micronuclei disintegrate. The fourth undergoes mitosis.

4. The two cells exchange a micronucleus.

5. The cells then separate.

6. The micronuclei in each cell fuse, forming a diploid micronucleus.

7. Mitosis occurs three times, giving rise to eight micronuclei.

8. Four of the new micronuclei transform into macronuclei, and the old macronucleus disintegrates.

9. Binary fission occurs twice, yielding four identical daughter cells.

In the asexual fission phase of growth, during which cell divisions occur by mitosis rather than meiosis, clonal aging occurs leading to a gradual loss of vitality. In some species, such as the well studied Paramecium tetraurelia, the asexual line of clonally aging Paramecia loses vitality and expires after about 200 fissions if the cells fail to undergo autogamy or conjugation. The basis for clonal aging was clarified by transplantation experiments of Aufderheide in 1986. When macronuclei of clonally young Paramecia were injected into Paramecia of standard clonal age, the lifespan (clonal fissions) of the recipient was prolonged. In contrast, transfer of cytoplasm from clonally young Paramecia did not prolong the lifespan of the recipient. These experiments indicated that the macronucleus, rather than the cytoplasm, is responsible for clonal aging. Other experiments by Smith-Sonneborn, Holmes and Holmes, and Gilley and Blackburn demonstrated that, during clonal aging, DNA damage increases dramatically. Thus, DNA damage in the macronucleus appears to be the cause of aging in P. tetraurelia. In this single-celled protist, aging appears to proceed as it does in multicellular eukaryotes, as described in DNA damage theory of aging.

When clonally aged P. tetraurelia are stimulated to undergo meiosis in association with either conjugation or automixis, the genetic descendants are rejuvenated, and are able to have many more mitotic binary fission divisions. During either of these processes, the micronuclei of the cell(s) undergo meiosis, the old macronucleus disintegrates and a new macronucleus is formed by replication of the micronuclear DNA that had recently undergone meiosis. There is apparently little, if any, DNA damage in the new macronucleus. These findings further solidify that clonal aging is due, in large part, to a progressive accumulation of DNA damage; and that rejuvenation is due to the repair of this damage in the micronucleus during meiosis. Meiosis appears to be an adaptation for DNA repair and rejuvenation in P. tetraurelia. In P. tetraurelia, CtlP protein is a key factor needed for the completion of meiosis during sexual reproduction and recovery of viable sexual progeny. The CtlP and Mre11 nuclease complex are essential for accurate processing and repair of double-strand breaks during homologous recombination.

Paramecium aurelia species complex:

Other species:

1. ^ Dobell, Clifford (1932). Antony van Leeuwenhoek and his "Little Animals" (1960 ed.). New York: Dover. pp. 164-165. ISBN 978-0-486-60594-4.

2. ^ Joblot, Louis (1718). Description et usages de Plusieurs Nouveaux Microscopes, tant simple que composez (in French). Vol. 2. Paris: Jacques Collombat. p. 79.

3. ^ Woodruff, Lorande Loss (September 1921). "The structure, life history, and intrageneric relationships of Paramecium calkinsi, sp. nov". The Biological Bulletin. 41 (3): 171-180. doi:10.2307/1536748. JSTOR 1536748.

4. ^ Curds, Colin R.; Gates, Michael; Roberts, David McL. (1983). British and other freshwater ciliated protozoa. Vol. 2. Cambridge University Press. p. 126.

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9. ^ Osterman, Natan; Vilfan, Andrej (September 20, 2011). "Finding the ciliary beating pattern with optimal efficiency" (PDF). Proceedings of the National Academy of Sciences. 108 (38): 15727-15732. arXiv:. Bibcode:2011PNAS..10815727O. doi:10.1073/pnas.1107889108. PMC . PMID 21896741.

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11. ^ Kreutz, Martin; Stoeck, Thorsten; Foissner, Wilhelm (2012). "Morphological and Molecular Characterization of Paramecium (Viridoparamecium nov. subgen.) chlorelligerum Kahl (Ciliophora)". Journal of Eukaryotic Microbiology. 59 (6): 548-563. doi:10.1111/j.1550-7408.2012.00638.x. PMC . PMID 22827482.

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13. ^ Lekomtsev, Sergey; Kolosov, Petr; Bidou, Laure; Frolova, Ludmila; Rousset, Jean-Pierre; Kisselev, Lev (June 26, 2007). "Different modes of stop codon restriction by the Stylonychia and Paramecium eRF1 translation termination factors". Proceedings of the National Academy of Sciences of the United States of America. 104 (26): 10824-9. Bibcode:2007PNAS..10410824L. doi:10.1073/pnas.0703887104. PMC . PMID 17573528.

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Paramecium ( PARR-ə-MEE-sh(ee-)əm , -⁠see-əm ; also spelled Paramoecium ) is a genus of eukaryotic, unicellular ciliates, commonly studied as a representative of the ciliate group. Paramecia are widespread in freshwater, brackish, and marine environments and are often very abundant in stagnant basins and ponds.

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Paramecium is a unicellular organism with a shape resembling the sole of a shoe. It ranges from 50 to 300um in size which varies from species to species. It is mostly found in a freshwater environment.

It is a single-celled eukaryote belonging to kingdom Protista and is a well-known genus of ciliate protozoa.

As well, it belongs to the phylum Ciliophora. Its whole body is covered with small hair-like filaments called the cilia which helps in locomotion. There is also a deep oral groove containing not so clear oral cilia. The main function of this cilia is to help both in locomotion as well as dragging the food to its oral cavity.

Classification of Paramecium

Paramecium can be classified into the following phylum and sub-phylum based on their certain characteristics.

Being a well-known ciliate protozoan, paramecium exhibits a high-level cellular differentiation containing several complex organelles performing a specific function to make its survival possible.

Besides a highly specialized structure, it also has a complex reproductive activity. Out of the 10 total species of Paramecium, the most common two are P.aurelia and P.caudatum.

Structure and Function

is a microscopic, unicellular protozoan. Its size ranges from 170 to 290um or up to 300 to 350um. Surprisingly, paramecium is visible to the naked eye and has an elongated slipper like shape, that's the reason it's also referred to as a slipper animalcule.

The posterior end of the body is pointed, thick and cone-like while the anterior part is broad and blunt. The widest part of the body is below the middle. The body of a paramecium is asymmetrical. It has a well-defined ventral or oral surface and has a convex aboral or dorsal body surface.

Its whole body is covered with a flexible, thin and firm membrane called pellicles. These pellicles are elastic in nature which supports the cell membrane. It is made up of a gelatinous substance.

Cilia refers to the multiple, small hair-like projections that cover the whole body. It is arranged in longitudinal rows with a uniform length throughout the body of the animal. This condition is called holotrichous. There are also a few longer cilia present at the posterior end of the body forming a caudal tuft of cilia, thus named caudatum.

The structure of cilia is the same as flagella, a sheath made of protoplast or plasma membrane with longitudinal nine fibrils in the form of a ring. The outer fibrils are much thicker than the inner ones with each cilium arising from a basal granule. Cilia have a diameter of 0.2um and helps in its locomotion.

It contains the following parts:

: Cytoplasm is a jelly-like substance further differentiated into the ectoplasm. The ectoplasm is a narrow peripheral layer. It is a dense and clear layer with an inner mass of endoplasm or semifluid plasmasol that is granular in shape.

The nucleus further consists of a macronucleus and a micronucleus.

is found close to the macronucleus. It is a small and compact structure, spherical in shape. The fine chromatin threads and granules are uniformly distributed throughout the cell and control reproduction of the cell. The number in a cell varies from species to species. There is no nucleolus present in Micro Nucleus: The micronucleus caudatum.

Paramecium consists of two types of vacuoles: contractile vacuole and food vacuole.

Characteristics

Paramecium has a worldwide distribution and is a free-living organism. It usually lives in the stagnant water of pools, lakes, ditches, ponds, freshwater and slow flowing water that is rich in decaying organic matter.

Its outer body is covered by the tiny hair-like structures called cilia. These cilia are in constant motion and help it move with a speed that is four times its body's length per second. Just as the organism moves forward, rotating around its own axis, this further helps it to push the food into the gullet. By reversing the motion of cilia, paramecium can move in the reverse direction as well.

Through a process known as phagocytosis, the food is pushed into the gullet through cilia which further goes into the food vacuoles.

The food is digested with the help of certain enzymes and hydrochloric acid. Once the digestion is completed the rest of the food content is quickly emptied into cytoproct also known as the pellicles.

The water absorbed from the surroundings through osmosis is continuously expelled from the body with the help of the contractile vacuoles present on either end of the cell. P. bursaria is one of the species which forms a symbiotic relationship with photosynthetic algae.

In this case, the paramecium provides a safe habitat for the algae to grow and live in its own cytoplasm, however, in return the paramecium might use this algae as a source of nutrition in case there is a scarcity of food in the surroundings.

Paramecium also feeds on other microorganisms like yeasts and bacteria. To gather the food it makes use of its cilia, making quick movements with cilia to draw the water along with its prey organisms inside the mouth opening through its oral groove.

The food further passes into the gullet through the mouth. Once there is enough food accumulated a vacuole is formed inside the cytoplasm, circulating through the cell with enzymes entering the vacuole through the cytoplasm to digest the food material.

Once the digestion is completed the vacuole starts to shrink and the digested nutrients enter into the cytoplasm. Once the vacuole reaches the anal pore with all of its digested nutrients it ruptures and expels all of its waste material into the environment.

Symbiosis refers to the mutual relationship between two organisms to benefit from each other. Some species of paramecium including P. bursaria and P. chlorelligerum form a symbiotic relationship with green algae from which they not only take food and nutrients when needed but also some protection from certain predators like Didinium nasutum.

There has been a lot of endosymbioses reported between the green algae and paramecium with an example being that of the bacteria named Kappa particles giving paramecium the power to kill other paramecium strains which lack this bacteria.

Just like all the other ciliates, paramecium also consists of one or more diploid micronuclei and a polypoid macronucleus hence containing a dual nuclear apparatus.

The function of the micronucleus is to maintain the genetic stability and making sure that the desirable genes are passed to the next generation. It is also called the germline or generative nucleus.

The macronucleus plays a role in non-reproductive cell functions including the expression of genes needed for the everyday functioning of the cell.

Paramecium reproduces asexually through binary fusion. The micronuclei during reproduction undergo mitosis while the macronuclei divide through amitosis. Each new cell, in the end, contains a copy of macronuclei and micronuclei after the cell undergoes a transverse division. Reproduction through binary fission may occur spontaneously.

It may also undergo autogamy (self-fertilization) under certain conditions. It may also follow a sexual reproduction process in which there is an exchange of genetic material because of mating between two paramecia who are compatible for mating through a temporary fusion.

There is a meiotic division of the micronuclei during the conjugation which results in haploid gametes and is further passed on from cell to cell. The old macronuclei are destroyed and formation of a diploid micronuclei takes place when gametes of two organisms fuse together.

Paramecium reproduces through conjugation and autogamy when conditions are not favorable and there is a scarcity of food.

There is a gradual loss of energy as a result of clonal aging during the mitotic cell division in the asexual fission phase of growth of paramecium.

P. tetraurelia is a well-studied species and it has been known that the cell expires right after 200 fissions if the cell relies only on the asexual line of cloning instead of conjugation and autogamy.

There is an increase in the DNA damage during clonal aging specifically the DNA damage in the macronucleus hence causing aging in P. tetraurelia. As per the DNA damage theory of aging the whole process of aging in single-celled protists is the same as that of the multicellular eukaryotes.

Strong evidence for the three whole-genome duplications has been provided after the genome of species P. tetraurelia has been sequenced. In some of the ciliates including Stylonychia and Paramecium UAA and UAG are designated as sense codons while UGA as a stop codon.

There have been some ambiguous results yielded, based on different experiments regarding whether or not paramecium exhibits the learning behavior.

There was a study published in 2006 which showed that P. causatum can be trained to differentiate between levels of brightness through a 6.5 volts electric current. For an organism with no nervous system, this type of finding is cited as a strong possible instance for epigenetic learning or cell memory.

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Paramecium - Classification, Structure, Function and Characteristics

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Paramecium is a unicellular organism with a shape resembling the sole of a shoe. It ranges from 50 to 300um in size which varies from species to species. It is mostly found in a freshwater environment. It is a single-celled eukaryote belonging to kingdom Protista and is a well-known genus of ciliate protozoa.