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Localised unwinding of a circular [[DNA|DNA]] molecule, which occurs during DNA replication, induces torsional stress into the remaining portion of the molecule because the ends of the strands are not free to rotate. As a result, the DNA molecule twists back on itself, like a twisted rubber band, forming supercoils <ref>Lodish,H.,Berk,A.,Kaiser,C.A.,Krieger,M.,Bretscher,A.,Ploegh,H., and Amon,A. (2013) Molecular Cell Biology,7th Edition, International Edition.</ref><br> | Localised unwinding of a circular [[DNA|DNA]] molecule, which occurs during DNA replication, induces torsional stress into the remaining portion of the molecule because the ends of the strands are not free to rotate. As a result, the DNA molecule twists back on itself, like a twisted rubber band, forming supercoils <ref>Lodish,H.,Berk,A.,Kaiser,C.A.,Krieger,M.,Bretscher,A.,Ploegh,H., and Amon,A. (2013) Molecular Cell Biology,7th Edition, International Edition.</ref><br> | ||
The supercoiling of DNA is a form of compaction of circular DNA duplex, as its segments are twisted around each other. In the relaxed state, the polynucleotide strands form a right-handed helix, in a pattern of ten nucleotide pair per turn. A underwound circular DNA duplex resists the cuts made by DNA topoismerase ezymes, by twisting opposite to the direction of underwinding, forming supercoils (Hartl, 2012) | |||
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=== References === | === References === | ||
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<ref>Hartl, D. L. (2012), Genetics: analysis of genes and genomes, 8th edition, Jones & Bartlett Learning</ref> | |||
Revision as of 08:52, 21 October 2014
Localised unwinding of a circular DNA molecule, which occurs during DNA replication, induces torsional stress into the remaining portion of the molecule because the ends of the strands are not free to rotate. As a result, the DNA molecule twists back on itself, like a twisted rubber band, forming supercoils [1]
The supercoiling of DNA is a form of compaction of circular DNA duplex, as its segments are twisted around each other. In the relaxed state, the polynucleotide strands form a right-handed helix, in a pattern of ten nucleotide pair per turn. A underwound circular DNA duplex resists the cuts made by DNA topoismerase ezymes, by twisting opposite to the direction of underwinding, forming supercoils (Hartl, 2012)
References
- ↑ Lodish,H.,Berk,A.,Kaiser,C.A.,Krieger,M.,Bretscher,A.,Ploegh,H., and Amon,A. (2013) Molecular Cell Biology,7th Edition, International Edition.
- ↑ Hartl, D. L. (2012), Genetics: analysis of genes and genomes, 8th edition, Jones & Bartlett Learning