BIOL 222 Lecture Notes - Lecture 4: Coiled Coil, Dna Supercoil, Dna Replication
9 Sep 2016
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Practice problems: if a does form a double helix, usually it is in a form, dna is mainly found in b form. Dna single or double stranded? ss or ds histones? no ds no. Dna ds yes (histone-like) yes circular or linear? either either circular (mostly) linear. Dna needs to have a balance between being compact enough to t within the cell, but also still able to provide access to the dna for replication and transcription. Dna supercoiling: a coiled coil, supercoils can be right ( ) or left (+) handed, just like dna helix"s. Overwinding = if dna is twisted in a right-handed direction, and produces a left-handed supercoil positive coil: more loose. Underwinding = when dna is turned in the left-handed direction, and produces a right- handed supercoil negative coil: more tight, most dna is found in a negative supercoil form, why supercoiling is important.
