MBB 222 Study Guide - Final Guide: Linking Number, Dna Supercoil, Dnaa
18 Dec 2016
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Document Summary
Dna is coiled in the form of a double helix structure where both strands wrap around the axis. Supercoiling means the coiling of a coil, so the further coiling of the dna axis upon itself. Supercoiling is important for compacting dna and regulating access to the genetic code. It also strongly affects dna metabolism and possibly gene expression. Relaxed state = when there is no net bending of the dna axis upon itself. For closed-circular molecule, defined with 1 turn of the double helix per 10. 5 bp. Supercoiled dna = when the axis of the dna double helix is coiled on itself to form a new helix (called a superhelix or supercoil) Dna compaction refers to how dna can be compacted via supercoiling and is important for various reasons in the cell. Many circular dna molecules remain highly supercoiled even after they are extracted and purified. Examples of small circular dnas include plasmids and small viral.
