GENET270 Lecture Notes - Lecture 3: Dna Supercoil, Synteny, Nucleoid
19 Jan 2017
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Document Summary
Mass of dna that represents 1000 x condensation of bacterial chromosome. Position of the chromosome within the bacterial cell is carefully coordinated- associated with the membrane, off to one side of the cell. Isolated chromosomes reveal: ~400 loops of dna, each is about 10 000 base pairs of. The nucleoid is dynamic -> influenced by dna replication, recombination, and transcription. Loops of dna are supercoiled-> dna is bent back on itself to under or over winding. Positive super coiling: dna is over wound, dna strands wrapped around each other more than in relaxed dna. Negative supercoiling: dna is under wound, less wrapped around each other than in relaxed dna. Structure dna by constraining supercoils to prevent twisting. As they separate the strands of dna for dna or rna synthesis, they introduce positive supercoils downstream. Bind dna by breaking one or both strands, passing dna through the break, and then resealing it. Dna sequencing technology allows rapid sequencing of bacterial genomes.
