Prokaryotes
Prokaryotes are the most abundant organisms that can be found on planet Earth. Most prokaryotes are uni-cellular, however they come in various shapes. The three most common shapes of prokaryotic cells are cocci, which are spherical shaped; bacilli, shaped as rods, and spiral shaped. Prokaryotes, however, do not have a nucleus or any other membrane-bound organelles. Prokaryotes DNA and all other inner cellular compartments are located together in the same area enclosed by cell membrane and are not separated into different cellular compartments as in Eukaryotes. The chromosome of prokaryotes is located in the nucleoid which is in a region of the cytoplasm. Prokaryotic cell independently replicates DNA molecules can be found smaller rings known as plasmids. Bacteria and Archaea are the two main domains within prokaryotic cells.
A bacterium represents the vast majority of prokaryotic species. Bacteria has become a synonym with sicknesses and disease, however, bacteria is also useful in some food processing procedures allowing foods such as yogurt and some cheese's to be edible. Prokaryote produce illness by poisons classified as exotoxins or endotoxins. The cell secretes exotoxins proteins which cause an adverse reaction in the body. Endotoxins are lippolysaccharide components of the outer membrane on gram negative bacteria. Unlike exotoxins which secrete the protein, endotoxins are released when the cell dies or its cell wall is broken down.
Structure and Movement
The cell wall of prokaryotes is surrounded by protein or a sticky layer of polysaccharide. This layer is called the capsule and it is well defined and dense, however, if this layer is less defined and not so well organized it is considered a slime layer. This outside layer allows the prokaryotes to stick to other substrates or other prokaryotes in a colony. This layer also prevents dehydration and can protect the prokaryote cell from attacks by the immune system (Campbell and Reece p.558)
As the capsule helps prokaryotes stick to other cells or substances, some prokaryotes have the ability to stick to other prokaryotes with tiny "hairlike" appendages' called fimbriae. The fimbriae, hair-like strands are made of proteins which help the cells attach to other cells or substrates.
Most prokaryotes can perform "taxis", or a method for moving itself. Some prokaryotes move by a process called chemotaxis. They change their movement pattern according to responses in chemicals around them. Surprisingly, if we can match their speed ratio, their size to the distance they move over time, to the movement ration of humans, some prokaryotes would be moving at close to 200 mph. Usian Bolt would not stand a chance against a prokaryote.
Reproduction
Prokaryote cells do not have the ability to reproduce sexually, but their diversity arises from genetic recombination. Meiosis and fertilization do not occur in prokaryotes. Through the processes of transformation, transduction, and conjugation, DNA is bought together from different individual prokaryote cells.
In transformation prokaryotic cell intakes foreign DNA, which can alter the cells genotype and phenotype, what it looks like and what it does. This cell is now a recombinant as the cell contains DNA from two different cells. Transduction happens when a cell, a donor, meets a host cell, and the virus has an inability to replicate its self, it can inject its prokaryotic DNA into a host cell to form another recombinant cell.
Lastly, conjugation occurs when DNA is transferred between two prokaryotic cells which are usually the same species. The DNA is transferred through hairlike fiber called a "Sex Pilus". One cell will be a host and donate its DNA to the recipient cell. The Pilus fibers reach out and connect like a hairlike bridge to allow DNA exchange.
Bacteria reproduce every 20 minutes.
Ecological Uses
Prokaryotes play a huge role in daily ecological interactions. Chemoheterotrophic prokaryotes perform decomposition. Without these cells breaking down dead organisms and waste products, dead life would just be stagnant lying on the earth. Life itself was cease, as the inability to breakdown these dead organisms would not allow other organisms to use the broken down compounds from these organisms to build other organic compounds for life to build on. These organic compounds then get passed on through the cycle of life.
Archaea - the other form
The other main form of Prokaryote cells is the domain of Archaea. An Archaea bacterium is the extreme environment survivors. These organisms are called Extremophile. They can compromise of halophiles which can survive in the saltiest, salinity, environments where they actually improve function as conditions become more saline. Also, thermophiles, can survive in the most "thermo" extreme temperature environments. Some prokaryotes are able to survive in temperatures of 250 degree Fahrenheit. These cells dwell around hydrothermal vents under the ocean or in deep sea springs. Other Archaea are considered methanogens. Archaea release methane as a byproduct by using carbon dioxide to produce hydrogen, energy, and methane as a waste product. Prokaryotes live in more moderate environments.
A bacterium represents the vast majority of prokaryotic species. Bacteria has become a synonym with sicknesses and disease, however, bacteria is also useful in some food processing procedures allowing foods such as yogurt and some cheese's to be edible. Prokaryote produce illness by poisons classified as exotoxins or endotoxins. The cell secretes exotoxins proteins which cause an adverse reaction in the body. Endotoxins are lippolysaccharide components of the outer membrane on gram negative bacteria. Unlike exotoxins which secrete the protein, endotoxins are released when the cell dies or its cell wall is broken down.
Structure and Movement
The cell wall of prokaryotes is surrounded by protein or a sticky layer of polysaccharide. This layer is called the capsule and it is well defined and dense, however, if this layer is less defined and not so well organized it is considered a slime layer. This outside layer allows the prokaryotes to stick to other substrates or other prokaryotes in a colony. This layer also prevents dehydration and can protect the prokaryote cell from attacks by the immune system (Campbell and Reece p.558)
As the capsule helps prokaryotes stick to other cells or substances, some prokaryotes have the ability to stick to other prokaryotes with tiny "hairlike" appendages' called fimbriae. The fimbriae, hair-like strands are made of proteins which help the cells attach to other cells or substrates.
Most prokaryotes can perform "taxis", or a method for moving itself. Some prokaryotes move by a process called chemotaxis. They change their movement pattern according to responses in chemicals around them. Surprisingly, if we can match their speed ratio, their size to the distance they move over time, to the movement ration of humans, some prokaryotes would be moving at close to 200 mph. Usian Bolt would not stand a chance against a prokaryote.
Reproduction
Prokaryote cells do not have the ability to reproduce sexually, but their diversity arises from genetic recombination. Meiosis and fertilization do not occur in prokaryotes. Through the processes of transformation, transduction, and conjugation, DNA is bought together from different individual prokaryote cells.
In transformation prokaryotic cell intakes foreign DNA, which can alter the cells genotype and phenotype, what it looks like and what it does. This cell is now a recombinant as the cell contains DNA from two different cells. Transduction happens when a cell, a donor, meets a host cell, and the virus has an inability to replicate its self, it can inject its prokaryotic DNA into a host cell to form another recombinant cell.
Lastly, conjugation occurs when DNA is transferred between two prokaryotic cells which are usually the same species. The DNA is transferred through hairlike fiber called a "Sex Pilus". One cell will be a host and donate its DNA to the recipient cell. The Pilus fibers reach out and connect like a hairlike bridge to allow DNA exchange.
Bacteria reproduce every 20 minutes.
Ecological Uses
Prokaryotes play a huge role in daily ecological interactions. Chemoheterotrophic prokaryotes perform decomposition. Without these cells breaking down dead organisms and waste products, dead life would just be stagnant lying on the earth. Life itself was cease, as the inability to breakdown these dead organisms would not allow other organisms to use the broken down compounds from these organisms to build other organic compounds for life to build on. These organic compounds then get passed on through the cycle of life.
Archaea - the other form
The other main form of Prokaryote cells is the domain of Archaea. An Archaea bacterium is the extreme environment survivors. These organisms are called Extremophile. They can compromise of halophiles which can survive in the saltiest, salinity, environments where they actually improve function as conditions become more saline. Also, thermophiles, can survive in the most "thermo" extreme temperature environments. Some prokaryotes are able to survive in temperatures of 250 degree Fahrenheit. These cells dwell around hydrothermal vents under the ocean or in deep sea springs. Other Archaea are considered methanogens. Archaea release methane as a byproduct by using carbon dioxide to produce hydrogen, energy, and methane as a waste product. Prokaryotes live in more moderate environments.
Prokaryote Diversity
View the many prokaryotes that live among us; in our bodies creating havoc,sickness, were as others are productive and meaningful to our human life .
Reference
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Gastroenterology Consultant of Augusta, "Helicobacter Pylori" retrieved February 24, 2013 from website, https://www.augustaendoscopy.com/digestive-health/helicobacter-pylori/
Homeland Security News Wire, "Promising antrax treatment studt results", retrieve February 24, 2913 from website, http://www.homelandsecuritynewswire.com/promising-anthrax-treatment-study-results
Microbial Physiology and Genetics (2005) retrieved from website February 24, 2013, http://biology200.gsu.edu/houghton/4595%20'04/lecture1.html
Noraxx Inspection incorporation, "Bacteria of the month", retrieved February 24, 2013 from website , http://www.noraxx.ca/bacteria.php
Quill Garphics 2012, "Cells Alive" retrieved February 24, 2013 from website, http://www.cellsalive.com
Rollin, David M., 2000, Pathogenic Microbiology, "Staphylococcus Summary" retrieved February 24, 2013 from website, http://www.life.umd.edu/classroom/bsci424/pathogendescriptions/Staphylococcus.htm
Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S.A., Minorsky, P.V., & Jackson, R.B., (2011). Campbell Biology (9th ed.). San Francisco, CA: Pearson Education, Inc.