Conjugation: Difference between revisions
Added a hyperlink for "Rolling-circle replication" |
Corrected punctuation. There should have a been a full stop instead of an ellipsis. Added a reference for the information on conjuation and F plasmid |
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Conjugation is "a form of | Conjugation is "a form of <a href="Sexual reproduction">sexual reproduction</a> seen in some <a href="Algae">algae</a>, some <a href="Bacteria">bacteria</a> and <a href="Ciliate protozoan">ciliate protozoans</a>". A tube (pilus) joins the two cells, growing out from one or both cells. Genetic information can then be passed from one cell (male) to the other cell (female). | ||
<a href="Plasmid">Plasmids</a> that can be transferred in this way are called conjugative plasmids - not all plasmids are conjugative plasmids. The <a href="F-plasmid">F-plasmid</a> is responsible for conjugation in ''<a href="Escherichia coli">Escherichia coli</a>'' - it encodes the proteins that are needed to produce the pilus that joins the two cells together. There are only one or two copies of the F-plasmid in each cell, it is aproximately 100kb in length and has many <a href="Genes">genes</a> that control its maintenance in the cell and its transmission between cells. Conjugation is started by physical contact between the two cells. It is controlled by a multisubunit, macromolecular protein structure, that is within the cytoplasm and inner membrane of the bacterium. DNA transfer always occurs along with plasmid replication. This is done by <a href="Rolling circle replication">rolling-circle replication</a>. This is where "replication starts with a singe-stranded cleavage at a specific sugar-phosphate bond in a double stranded circle. This cleavage produces two chemically distinct ends. DNA is synthesised by the addition of successive deoxyribonucleotides to the 3' end with simultaneous displacement of the 5' end from the circle. As replication proceeds around the circle, the 5' end 'rolls out' as a tail of increasing length". The transfer of the F plasmid requires only a few minutes to complete. | |||
Revision as of 21:45, 5 December 2017
Conjugation is "a form of <a href="Sexual reproduction">sexual reproduction</a> seen in some <a href="Algae">algae</a>, some <a href="Bacteria">bacteria</a> and <a href="Ciliate protozoan">ciliate protozoans</a>". A tube (pilus) joins the two cells, growing out from one or both cells. Genetic information can then be passed from one cell (male) to the other cell (female).
<a href="Plasmid">Plasmids</a> that can be transferred in this way are called conjugative plasmids - not all plasmids are conjugative plasmids. The <a href="F-plasmid">F-plasmid</a> is responsible for conjugation in <a href="Escherichia coli">Escherichia coli</a> - it encodes the proteins that are needed to produce the pilus that joins the two cells together. There are only one or two copies of the F-plasmid in each cell, it is aproximately 100kb in length and has many <a href="Genes">genes</a> that control its maintenance in the cell and its transmission between cells. Conjugation is started by physical contact between the two cells. It is controlled by a multisubunit, macromolecular protein structure, that is within the cytoplasm and inner membrane of the bacterium. DNA transfer always occurs along with plasmid replication. This is done by <a href="Rolling circle replication">rolling-circle replication</a>. This is where "replication starts with a singe-stranded cleavage at a specific sugar-phosphate bond in a double stranded circle. This cleavage produces two chemically distinct ends. DNA is synthesised by the addition of successive deoxyribonucleotides to the 3' end with simultaneous displacement of the 5' end from the circle. As replication proceeds around the circle, the 5' end 'rolls out' as a tail of increasing length". The transfer of the F plasmid requires only a few minutes to complete.