By maintaining the unbound DNA in a relaxed state, topoisomerases facilitate the binding of histones to the DNA and the formation of additional nucleosomes.

Importantly, the overall effect on the plasmid is that the linking number is decreased as more nucleosomes are assembled

TLS Online TPP Program

#Id: 6365

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6366

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6367

#Unit 2. Cellular Organization

This 21-bp sequence is twofold symmetric and is recognized by two subunits of Lac repressor, one binding to each half-site

TLS Online TPP Program

#Id: 6368

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6369

#Unit 2. Cellular Organization

When polymerase binding causes transition to the open complex and initiates transcription. This gives a low level of constitutive expression called the basal level.  Binding of RNA polymerase is the rate-limiting step in this case.

TLS Online TPP Program

#Id: 6370

#Unit 2. Cellular Organization

Lac repressor binds as a tetramer to two operators.