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‘sticky’ ends

2014-10-20T10:42:55Z

130319902:

A [[Restriction enzyme|restriction enzyme]] can cut [[DNA|DNA]] at a specific sequence of [[Nucleotides|nucleotides]] usually 4, 6 or 8 [[Nucleotides|nucleotides]] long. This may result in [[Blunt ends|symmetrical cleavage]] leading to [[Blunt ends|blunt ends]] or [['sticky' ends|assymetrical cleavage]] causing [['sticky' ends|sticky ends]]. A [['sticky' ends|"sticky" end is]] produced when the [[Restriction enzyme|restriction enzyme]] cuts at one end of the sequence, between two bases on the same strand, then cuts on the opposite end of the [[Complementary strand|complementary strand]]. This will produce two ends of [[DNA|DNA]] that will have some [[Nucleotides|nucleotides]] without any complementary bases. A [[Restriction enzyme|restriction enzyme]] will only cut at a specific sequence, and it recognises palindromic sequence that is, sequences that are the same whether they are read forwards or backwards. These "sticky" ends allow the insertion of 'foreign' DNA into the host [[Genome|genome]]. By cutting the plasmid with the same restriction [[Enzyme|enzyme]], the same 'sticky ends' are produced. For example, complementary bases of the plasmid can pair with those of the host DNA and form hydrogen bonds which anneal the two strands together. However, there will still be nicks in the [https://teaching.ncl.ac.uk/bms/wiki/index.php/Phosphodiester_bond phosphodiester bonds ]which form the rigid phosphate backbone of DNA. In this scenario DNA ligase can be added which will form the phosphodiester bonds between the recombinant strands. The [[Genes|genes]] carried on the plasmid will now be incorporated into the hosts genome.

Also see [[Blunt end|"blunt" ends]].

‘sticky’ ends

2014-10-20T10:42:40Z

130319902:

A [[Restriction enzyme|restriction enzyme]] can cut [[DNA|DNA]] at a specific sequence of [[Nucleotides|nucleotides]] usually 4, 6 or 8 [[Nucleotides|nucleotides]] long. This may result in [[Blunt ends|symmetrical cleavage]] leading to [[Blunt ends|blunt ends]] or [['sticky' ends|assymetrical cleavage]] causing [['sticky' ends|sticky ends]]. A [['sticky' ends|"sticky" end is]] produced when the [[Restriction enzyme|restriction enzyme]] cuts at one end of the sequence, between two bases on the same strand, then cuts on the opposite end of the [[Complementary strand|complementary strand]]. This will produce two ends of [[DNA|DNA]] that will have some [[Nucleotides|nucleotides]] without any complementary bases. A [[Restriction enzyme|restriction enzyme]] will only cut at a specific sequence, and it recognises palindromic sequence that is, sequences that are the same whether they are read forwards or backwards. These "sticky" ends allow the insertion of 'foreign' DNA into the host [[Genome|genome]]<ref>http://www.scienceaid.co.uk/biology/genetics/engineering.html</ref>. By cutting the plasmid with the same restriction [[Enzyme|enzyme]], the same 'sticky ends' are produced. For example, complementary bases of the plasmid can pair with those of the host DNA and form hydrogen bonds which anneal the two strands together. However, there will still be nicks in the [https://teaching.ncl.ac.uk/bms/wiki/index.php/Phosphodiester_bond phosphodiester bonds ]which form the rigid phosphate backbone of DNA. In this scenario DNA ligase can be added which will form the phosphodiester bonds between the recombinant strands. The [[Genes|genes]] carried on the plasmid will now be incorporated into the hosts genome.

Also see [[Blunt end|"blunt" ends]].

1.<ref>http://www.scienceaid.co.uk/biology/genetics/engineering.html</ref>

‘sticky’ ends

2014-10-20T10:42:09Z

130319902:

A [[Restriction enzyme|restriction enzyme]] can cut [[DNA|DNA]] at a specific sequence of [[Nucleotides|nucleotides]] usually 4, 6 or 8 [[Nucleotides|nucleotides]] long. This may result in [[Blunt ends|symmetrical cleavage]] leading to [[Blunt ends|blunt ends]] or [['sticky' ends|assymetrical cleavage]] causing [['sticky' ends|sticky ends]]. A [['sticky' ends|"sticky" end is]] produced when the [[Restriction enzyme|restriction enzyme]] cuts at one end of the sequence, between two bases on the same strand, then cuts on the opposite end of the [[Complementary strand|complementary strand]]. This will produce two ends of [[DNA|DNA]] that will have some [[Nucleotides|nucleotides]] without any complementary bases. A [[Restriction enzyme|restriction enzyme]] will only cut at a specific sequence, and it recognises palindromic sequence that is, sequences that are the same whether they are read forwards or backwards. These "sticky" ends allow the insertion of 'foreign' DNA into the host [[Genome|genome]]<ref>http://www.scienceaid.co.uk/biology/genetics/engineering.html</ref>. By cutting the plasmid with the same restriction [[Enzyme|enzyme]], the same 'sticky ends' are produced. For example, complementary bases of the plasmid can pair with those of the host DNA and form hydrogen bonds which anneal the two strands together. However, there will still be nicks in the [https://teaching.ncl.ac.uk/bms/wiki/index.php/Phosphodiester_bond phosphodiester bonds ]which form the rigid phosphate backbone of DNA. In this scenario DNA ligase can be added which will form the phosphodiester bonds between the recombinant strands. The [[Genes|genes]] carried on the plasmid will now be incorporated into the hosts genome.

Also see [[Blunt end|"blunt" ends]].

‘sticky’ ends

2014-10-20T10:41:33Z

130319902:

A [[Restriction enzyme|restriction enzyme]] can cut [[DNA|DNA]] at a specific sequence of [[Nucleotides|nucleotides]] usually 4, 6 or 8 [[Nucleotides|nucleotides]] long. This may result in [[Blunt ends|symmetrical cleavage]] leading to [[Blunt ends|blunt ends]] or [['sticky' ends|assymetrical cleavage]] causing [['sticky' ends|sticky ends]]. A [['sticky' ends|"sticky" end is]] produced when the [[Restriction enzyme|restriction enzyme]] cuts at one end of the sequence, between two bases on the same strand, then cuts on the opposite end of the [[Complementary strand|complementary strand]]. This will produce two ends of [[DNA|DNA]] that will have some [[Nucleotides|nucleotides]] without any complementary bases. A [[Restriction enzyme|restriction enzyme]] will only cut at a specific sequence, and it recognises palindromic sequence that is, sequences that are the same whether they are read forwards or backwards. These "sticky" ends allow the insertion of 'foreign' DNA into the host [[Genome|genome]]<ref name="1">http://www.scienceaid.co.uk/biology/genetics/engineering.html</ref>. By cutting the plasmid with the same restriction [[Enzyme|enzyme]], the same 'sticky ends' are produced. For example, complementary bases of the plasmid can pair with those of the host DNA and form hydrogen bonds which anneal the two strands together. However, there will still be nicks in the [https://teaching.ncl.ac.uk/bms/wiki/index.php/Phosphodiester_bond phosphodiester bonds ]which form the rigid phosphate backbone of DNA. In this scenario DNA ligase can be added which will form the phosphodiester bonds between the recombinant strands. The [[Genes|genes]] carried on the plasmid will now be incorporated into the hosts genome.

Also see [[Blunt end|"blunt" ends]].

Myelinated axons

2013-11-28T21:48:45Z

130319902:

A [[Myelinated_axons|myelinated axon]] is one which is surrounded by a myelin sheath, comprised of [[Schwann cells|Schwann cells]] <ref name="null">Lodish, Laisser, Bretscher, Amon, Berk, Krieger, Ploegh, Scott (2012) , Molecular Cell Biology, 7th Edition, New York, WH Freeman</ref>.  It is electrically insulating, except for gaps in the sheath which are called the [[Nodes of Ranvier|Nodes of Ranvier]]. This insulation increases the speed of transmission of [[Action potential|action potentials]]. Due to the gaps in the myelin sheath, action potentials propagate by [[Saltatory conduction|saltatory conduction]]. Where action potentials jump between the nodes, there is a higher abundance of ion channels. Conduction in myelinated axons is faster than in an unmyelinated axon as the impluse 'jumps' from one Node of Ranvier to another<ref>Alberts B., Johnson A., Lewis J., Raff M., Roberts K. and Walters P. (2008). Molecular biology of the cell. 5th ed. New York: Garland Science. p680.</ref>.

 

=== References ===

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Myelinated axons

2013-11-28T21:47:30Z

130319902: