Paramecium Cells

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[[Eukaryotic cells|''Paramecium'' cells]] are large unicellular organisms. Paramecium is a genus, there are four different species; paramecium aurelia, paramecium bursaria, paramecium caudatum and&nbsp;paramecium tetraurelia.<ref>Lynn H. (2008) The ciliated protozoa characterisation, classification and guide to the literatuer, New York: Springer</ref>&nbsp;They are part of the [[Eukaryotes|eukaryotic]] family, thus meaning that they have membrane-bound [[Organelles|organelles]].  
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[[Eukaryotic cells|''Paramecium'' cells]] are large [[Unicellular|unicellular]] organisms. Paramecium is a genus, there are four different [[Species|species]]; paramecium aurelia, paramecium bursaria, paramecium caudatum and paramecium tetraurelia<ref>Lynn H. (2008) The ciliated protozoa characterisation, classification and guide to the literature, New York: Springer</ref>. They are part of the [[Eukaryotes|eukaryotic]] family, thus meaning that they have membrane-bound [[Organelles|organelles]].  
  
Paramecium is free living ciliated [[Protozoa|Protozoa]], its&nbsp;cell body is surrounded by&nbsp;[[Cilia|cilia]].&nbsp;There are two main functions of these cilia. &nbsp;Firstly they allow paramecium to move around its freshwater habitat.&nbsp;Secondly, they are also used to waft small bacteria and algaes into the gullet (a large invagination in the cell membrane) where they are [[Endocytosis|endocytosed]] and assymilated into the cell. All waste excess is exctreted via the anal pore.<br>
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Paramecium is free-living [[Cilia|ciliated]] [[Protozoa|Protozoa]], its cell body is surrounded by [[Cilia|cilia]]. There are two main functions of these [[Cilia|cilia]]. Firstly they allow paramecium to move around its freshwater habitat. Secondly, they are also used to waft small bacteria and [[Algae|algaes]] into the gullet (a large invagination in the cell membrane) where they are [[Endocytosis|endocytosed]] and assimilated into the cell. All waste excess is excreted via the anal pore.  
  
Paramecium also use trichocysts (spear-like structures that protrude from the cell) as a defence mechanism to help protect themselves from predators.<ref name="null">Beale, Geoffrey (2008) Paramecium Genetics and Epigentics CRC Press, Taylor and Fancis Group, Pg 23</ref>&nbsp;This YouTube video shows the discharge of trichocysts:&nbsp;[http://youtu.be/5eDYfcdE7ns youtu.be/5eDYfcdE7ns]<br>
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Paramecium also use trichocysts (spear-like structures that protrude from the cell) as a defence mechanism to help protect themselves from predators<ref name="null">Beale, Geoffrey (2008) Paramecium Genetics and Epigenetics CRC Press, Taylor and Francis Group, Pg 23</ref>. This YouTube video shows the discharge of trichocysts: [http://youtu.be/5eDYfcdE7ns youtu.be/5eDYfcdE7ns]  
  
A Paramecium cell has two nuclei, the germinal nucleus also known as the micro-nucleus is involved in sexual processes. Fundamentally the transfer of genetic information; meiosis is conducted as this nucleus. The somatic nucleus, also known as the macro-nucleus participates in the process of transcription and ensures expression of genetic information.<br>
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A Paramecium cell has two [[Nuclei|nuclei]], the germinal nucleus also known as the micronucleus is involved in sexual processes. Fundamentally the transfer of genetic information; [[Meiosis|meiosis]] is conducted as this nucleus. The somatic nucleus, also known as the macro-nucleus participates in the process of transcription and ensures the expression of genetic information.  
  
Paramecium lives in a freshwater environment which in the abscence of&nbsp;[[Contractile vauoles|contractile vacuoles]]&nbsp;would burst this is&nbsp;caused by the [[Osmosis|osmotic]] uptake of water, by a process known as [[Osmoregulation|osmoregulation]]&nbsp;<ref name="(Beale G. & Preer J,2008).">Beale, Goffey and Preer, John R. Jr. (2008) Paramecium Genetics and Epigenetics CRC Press, Taylor and Francis Group.</ref>.&nbsp;Near to the cell surface membrane, [[Contractile vauoles|contractile vacuoles]]&nbsp;have canals. These contain vacuole fluid with an osmolarity, controlled by Cl<sup>-</sup> and K<sup>+</sup>, that is higher than the osmolarity of the cytoplasm. This allows water to enter the canals passively through osmosis<ref>Stock C., Gronlein H.K., Allen D., Naitoh Y., 2002, Osmoregulation in paramecium; in situ ion gradients permit water to cascade through cytosol to the contractile vacuole, Journal of cell science, vol. 115 pages 2339-2348</ref>. Once the water has entered the vacuole the pore opens and the vacuole contracts expelling the water. Within close proximity of the [[Contractile vauoles|contractile vacuoles]] are many [[Mitochondria|mitochondria]] and this is due to the face that the [[Organelles|organelles]] require [[ATP|ATP]] as its source of energy.<br>
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Paramecium lives in a freshwater environment which in the absence of [[Contractile vauoles|contractile vacuoles]] would burst this is caused by the [[Osmosis|osmotic]] uptake of water, by a process known as [[Osmoregulation|osmoregulation]]<ref name="(Beale G. & Preer J,2008).">Beale, Goffey and Preer, John R. Jr. (2008) Paramecium Genetics and Epigenetics CRC Press, Taylor and Francis Group.</ref>. Near to the [[Plasma membrane|cell surface membrane]], [[Contractile vauoles|contractile vacuoles]] have canals. These contain [[Vacuole|vacuole]] fluid with an [[Osmolarity|osmolarity]], controlled by [[Chloride|Cl<sup>-</sup>]] and [[Potassium ions|K<sup>+</sup>]], that is higher than the osmolarity of the [[Cytoplasm|cytoplasm]]. This allows water to enter the canals passively through osmosis<ref>Stock C., Gronlein H.K., Allen D., Naitoh Y., 2002, Osmoregulation in paramecium; in situ ion gradients permit water to cascade through cytosol to the contractile vacuole, Journal of cell science, vol. 115 pages 2339-2348</ref>. Once the water has entered the vacuole the pore opens and the vacuole contracts expelling the water. Within close proximity of the [[Contractile vauoles|contractile vacuoles]] are many [[Mitochondria|mitochondria]] and this is due to the face that the [[Organelles|organelles]] require [[ATP|ATP]] as its source of [[Energy|energy]].  
  
The Paramecium cell reproduces by a process called&nbsp;[[Reproduction by Conjugation|conjugation]]&nbsp;<ref>L.Prescott, J.Hardley and D.Klein Microbiology 6th Edition New York:McGraw-Hill</ref>&nbsp;and&nbsp;[[Asexual fission|asexual fission]]. &nbsp;&nbsp;Asexual fission creates two genetically identical daughter cells.<br>
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The Paramecium cell reproduces by a process called [[Reproduction by Conjugation|conjugation]]<ref>L.Prescott, J.Hardley and D.Klein Microbiology 6th Edition New York:McGraw-Hill</ref>. and [[Asexual fission|asexual fission]]. Asexual fission creates two genetically identical [[Daughter cells|daughter cells]].  
  
Paramecium has [[Action potentials|action potentials not]] unlike those that occur in [[Neuron|neurons]]. &nbsp;However, in Paramecium,&nbsp;calcium ions enter the cell through voltage gated channels and cause the rapid depolarisation of the membrane<ref>Hinrichsen, R. and Schultz, J. (1988) “Paramecium: a model system for the study of excitable cells” Trends in Neurosciences, vol 11, no. 1, pp. 28</ref>&nbsp;and generate an action potential, rather than the sodium ions (as in neurones). The repolarising phase is due to the closing of the calcium ion channels and the opening of the potassium ion channels&nbsp;<ref>Eckert, R. and Brehm, P. (1979) Ionic Mechanisms of Excitation in Paramecium. Annual Review of Biophysics and Bioengineering. 8, 353-383</ref>.<br>
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Paramecium has [[Action potentials|action potentials not]] unlike those that occur in [[Neuron|neurons]]. However, in Paramecium, calcium ions enter the cell through [[Voltage-gated ion channel|voltage gated channels]] and cause the rapid [[Depolarisation|depolarisation]] of the membrane<ref>Hinrichsen, R. and Schultz, J. (1988) “Paramecium: a model system for the study of excitable cells” Trends in Neurosciences, vol 11, no. 1, pp. 28</ref>. and generate an action potential, rather than the [[Sodium ions|sodium ions ]](as in neurones). The repolarising phase is due to the closing of the calcium ion channels and the opening of the potassium ion channels<ref>Eckert, R. and Brehm, P. (1979) Ionic Mechanisms of Excitation in Paramecium. Annual Review of Biophysics and Bioengineering. 8, 353-383</ref>.  
  
The length of a typical [[Cell|''paramecium'']] varies from 100 μm to 300 μm&nbsp;<ref>Brock Biology of Micro-organisms 12th Edition, Madigan Dunlap Clark, Pg 69</ref>. They can be found in freshwater areas, like rivers, ponds and lakes <ref>Holtzman E, Novikoff A (1984) Cells and Organelles, 3rd edition, USA, CBS College Publishing</ref>.<br>
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The length of a typical [[Cell|''paramecium'']] varies from 100 μm to 300 μm<ref>Brock Biology of Micro-organisms 12th Edition, Madigan Dunlap Clark, Pg 69</ref>. They can be found in freshwater areas, like rivers, ponds and lakes<ref>Holtzman E, Novikoff A (1984) Cells and Organelles, 3rd edition, USA, CBS College Publishing</ref>.  
  
Paramecium cells are capable of regulated [[Exocytosis|exocytosis]] when triggered by an external stimulus. This exocytosis is similar to the release of [[Neurotransmitter|neurotransmitters]] by the [[Presynaptic membrane|presynaptic membrane at]] a [[Synapse|synapse]]. However instead of using it for signalling and depolarising the [[Postsynaptic membrane|postsynaptic membrane]], it is used as a defence mechanism against predators&nbsp;<ref>Genoscope (2007) Paramecium tetraurelia: Paramecium, a model ciliate</ref><ref>Wincker P (1st November 2006) Nature 444 171-178 Global trends of the whole-genome duplications revealed by the ciliate Paramecium tetraurelia 29th November 2012</ref>.<br>
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Paramecium cells are capable of regulated [[Exocytosis|exocytosis]] when triggered by an external [[Stimulus|stimulus]]. This exocytosis is similar to the release of [[Neurotransmitter|neurotransmitters]] by the [[Presynaptic membrane|presynaptic membrane at]] a [[Synapse|synapse]]. However instead of using it for signalling and depolarising the [[Postsynaptic membrane|postsynaptic membrane]], it is used as a defence mechanism against predators<ref>Genoscope (2007) Paramecium tetraurelia: Paramecium, a model ciliate</ref><ref>Wincker P (1st November 2006) Nature 444 171-178 Global trends of the whole-genome duplications revealed by the ciliate Paramecium tetraurelia 29th November 2012</ref>.  
  
According Beale; ‘one hypothesis suggests that ''Paramecium''&nbsp;has been round even before the continents separated and has not moved; only continents have’. That is why the ciliated protozoa is readily found all over the world living in fresh water and feed on microscopic organisms such as bacteria and single-celled algae and move by propelling their cilia, back and forth in prompted quick succession (Beale &amp; Preer., 2008: 16).  
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According to Beale; ‘one hypothesis suggests that ''Paramecium'' has been round even before the continents separated and has not moved; only continents have’. That is why the ciliated protozoa is readily found all over the world living in fresh water and feed on microscopic organisms such as bacteria and single-celled algae and move by propelling their cilia, back and forth in prompted quick succession (Beale &amp; Preer., 2008: 16).  
  
As one of the oldest primitive organisms on earth, ''Paramecia'' are among the first organisms used to clarify the Universal&nbsp;genetic code. It is still of much historical interest to geneticists, today, known to use a variant genetic code (UAA and UAG = Glu not stop).  
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As one of the oldest primitive organisms on earth, ''Paramecia'' are among the first organisms used to clarify the [[Genetic code|Universal genetic code]]. It is still of much historical interest to geneticists, today, known to use a variant genetic code (UAA and UAG = Glu not stop).  
  
Like most other single celled organism, they divide by binary fission. Occasionally, ''Paramecia ''exchange genetic material in a kind of primitive sexual reproduction using a parole cone like protuberance which passes gamete nuclei from one conjugate to another.  
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Like most other single-celled organism, they divide by binary fission. Occasionally, ''Paramecia ''exchange genetic material in a kind of primitive sexual reproduction using a parole cone-like protuberance which passes [[Gamete|gamete]] nuclei from one conjugate to another.  
  
A peculiar behavioral response is demonstrated by ''Paramecia;'' when exposed to any physical or chemical stimuli they propel faster or discharge a spine-like structure from their outer coating called trichocyst at the stimulus as a protective defense measure against being pursued or devoured by predators.  
+
A peculiar behavioural response is demonstrated by ''Paramecia;'' when exposed to any physical or chemical stimuli they propel faster or discharge a spine-like structure from their outer coating called trichocyst at the stimulus as a protective defence measure against being pursued or devoured by predators.  
  
Studying ''Paramecium'' cell has produced concepts that are widely accepted to advance knowledge leading to a better understanding of mechanisms like the muscle sliding filament phenomenon and the evolution of the neuronal functions of higher organisms<ref>Beale, G.H. and Preer, J. R. (2008). Paramecium Genetics and Epigenetics, e-book, accessed 26 November 2012 from http://www.ncl.ac.uk/library/e-books.</ref><ref>Hames, D. and Hooper, N. (2011) BIOS Instant notes: Biochemistry, 4th edition, New York: Garland Science.</ref>.<br>
+
Studying ''Paramecium'' cell has produced concepts that are widely accepted to advance knowledge leading to a better understanding of mechanisms like the muscle sliding filament phenomenon and the evolution of the neuronal functions of higher organisms<ref>Beale, G.H. and Preer, J. R. (2008). Paramecium Genetics and Epigenetics, e-book, accessed 26 November 2012 from http://www.ncl.ac.uk/library/e-books.</ref><ref>Hames, D. and Hooper, N. (2011) BIOS Instant notes: Biochemistry, 4th edition, New York: Garland Science.</ref>.  
  
 
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Latest revision as of 17:11, 23 October 2018

Paramecium cells are large unicellular organisms. Paramecium is a genus, there are four different species; paramecium aurelia, paramecium bursaria, paramecium caudatum and paramecium tetraurelia[1]. They are part of the eukaryotic family, thus meaning that they have membrane-bound organelles.

Paramecium is free-living ciliated Protozoa, its cell body is surrounded by cilia. There are two main functions of these cilia. Firstly they allow paramecium to move around its freshwater habitat. Secondly, they are also used to waft small bacteria and algaes into the gullet (a large invagination in the cell membrane) where they are endocytosed and assimilated into the cell. All waste excess is excreted via the anal pore.

Paramecium also use trichocysts (spear-like structures that protrude from the cell) as a defence mechanism to help protect themselves from predators[2]. This YouTube video shows the discharge of trichocysts: youtu.be/5eDYfcdE7ns

A Paramecium cell has two nuclei, the germinal nucleus also known as the micronucleus is involved in sexual processes. Fundamentally the transfer of genetic information; meiosis is conducted as this nucleus. The somatic nucleus, also known as the macro-nucleus participates in the process of transcription and ensures the expression of genetic information.

Paramecium lives in a freshwater environment which in the absence of contractile vacuoles would burst this is caused by the osmotic uptake of water, by a process known as osmoregulation[3]. Near to the cell surface membrane, contractile vacuoles have canals. These contain vacuole fluid with an osmolarity, controlled by Cl- and K+, that is higher than the osmolarity of the cytoplasm. This allows water to enter the canals passively through osmosis[4]. Once the water has entered the vacuole the pore opens and the vacuole contracts expelling the water. Within close proximity of the contractile vacuoles are many mitochondria and this is due to the face that the organelles require ATP as its source of energy.

The Paramecium cell reproduces by a process called conjugation[5]. and asexual fission. Asexual fission creates two genetically identical daughter cells.

Paramecium has action potentials not unlike those that occur in neurons. However, in Paramecium, calcium ions enter the cell through voltage gated channels and cause the rapid depolarisation of the membrane[6]. and generate an action potential, rather than the sodium ions (as in neurones). The repolarising phase is due to the closing of the calcium ion channels and the opening of the potassium ion channels[7].

The length of a typical paramecium varies from 100 μm to 300 μm[8]. They can be found in freshwater areas, like rivers, ponds and lakes[9].

Paramecium cells are capable of regulated exocytosis when triggered by an external stimulus. This exocytosis is similar to the release of neurotransmitters by the presynaptic membrane at a synapse. However instead of using it for signalling and depolarising the postsynaptic membrane, it is used as a defence mechanism against predators[10][11].

According to Beale; ‘one hypothesis suggests that Paramecium has been round even before the continents separated and has not moved; only continents have’. That is why the ciliated protozoa is readily found all over the world living in fresh water and feed on microscopic organisms such as bacteria and single-celled algae and move by propelling their cilia, back and forth in prompted quick succession (Beale & Preer., 2008: 16).

As one of the oldest primitive organisms on earth, Paramecia are among the first organisms used to clarify the Universal genetic code. It is still of much historical interest to geneticists, today, known to use a variant genetic code (UAA and UAG = Glu not stop).

Like most other single-celled organism, they divide by binary fission. Occasionally, Paramecia exchange genetic material in a kind of primitive sexual reproduction using a parole cone-like protuberance which passes gamete nuclei from one conjugate to another.

A peculiar behavioural response is demonstrated by Paramecia; when exposed to any physical or chemical stimuli they propel faster or discharge a spine-like structure from their outer coating called trichocyst at the stimulus as a protective defence measure against being pursued or devoured by predators.

Studying Paramecium cell has produced concepts that are widely accepted to advance knowledge leading to a better understanding of mechanisms like the muscle sliding filament phenomenon and the evolution of the neuronal functions of higher organisms[12][13].

References:

  1. Lynn H. (2008) The ciliated protozoa characterisation, classification and guide to the literature, New York: Springer
  2. Beale, Geoffrey (2008) Paramecium Genetics and Epigenetics CRC Press, Taylor and Francis Group, Pg 23
  3. Beale, Goffey and Preer, John R. Jr. (2008) Paramecium Genetics and Epigenetics CRC Press, Taylor and Francis Group.
  4. Stock C., Gronlein H.K., Allen D., Naitoh Y., 2002, Osmoregulation in paramecium; in situ ion gradients permit water to cascade through cytosol to the contractile vacuole, Journal of cell science, vol. 115 pages 2339-2348
  5. L.Prescott, J.Hardley and D.Klein Microbiology 6th Edition New York:McGraw-Hill
  6. Hinrichsen, R. and Schultz, J. (1988) “Paramecium: a model system for the study of excitable cells” Trends in Neurosciences, vol 11, no. 1, pp. 28
  7. Eckert, R. and Brehm, P. (1979) Ionic Mechanisms of Excitation in Paramecium. Annual Review of Biophysics and Bioengineering. 8, 353-383
  8. Brock Biology of Micro-organisms 12th Edition, Madigan Dunlap Clark, Pg 69
  9. Holtzman E, Novikoff A (1984) Cells and Organelles, 3rd edition, USA, CBS College Publishing
  10. Genoscope (2007) Paramecium tetraurelia: Paramecium, a model ciliate
  11. Wincker P (1st November 2006) Nature 444 171-178 Global trends of the whole-genome duplications revealed by the ciliate Paramecium tetraurelia 29th November 2012
  12. Beale, G.H. and Preer, J. R. (2008). Paramecium Genetics and Epigenetics, e-book, accessed 26 November 2012 from http://www.ncl.ac.uk/library/e-books.
  13. Hames, D. and Hooper, N. (2011) BIOS Instant notes: Biochemistry, 4th edition, New York: Garland Science.
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