Figure 6-20

Superhelical pressure during the DNA causes DNA supercoiling. (A) Getting an effective DNA molecule that have that 100 % free avoid (otherwise good nick in a single string you to functions as a great swivel), the brand new DNA twice helix rotates of the one change for each ten nucleotide pairs launched. (B) If rotation is actually averted, (a great deal more. )

Superhelical stress is additionally created as RNA polymerase actions collectively an effective expand from DNA that’s anchored at the their finishes (Profile 6-20C). Provided the polymerase is not absolve to switch easily (and you may such as rotation was impractical because of the sized RNA polymerases as well as their connected transcripts), a relocation polymerase builds confident superhelical tension from the DNA in front from it and negative helical pressure at the rear of they. (más…)