Drosophila telomeres are an exception, consisting of terminal arrays of retrotransposons.

TLS Online TPP Program

#Id: 2291

#Unit 3. Fundamental Processes

Isomerization, does not require energy derived from ATP hydrolysis and is instead the result of a spontaneous conformational change in the DNA– enzyme complex to a more energetically favorable form. 

TLS Online TPP Program

#Id: 2292

#Unit 3. Fundamental Processes

Isomerization is essentially irreversible and once complete, typically guarantees that transcription will subsequently initiate .

TLS Online TPP Program

#Id: 2293

#Unit 3. Fundamental Processes

Formation of the closed complex, in contrast, is readily reversible: polymerase can as easily dissociate from the promoter as make the transition to the open complex.

TLS Online TPP Program

#Id: 2294

#Unit 3. Fundamental Processes

During initial transcription, the polymerase remains stationary on the promoter, unwinds downstream DNA, and pulls that DNA into itself

TLS Online TPP Program

#Id: 2295

#Unit 3. Fundamental Processes

scrunching model -proposes that DNA downstream from the stationary, promoter-bound, polymerase is unwound and pulled into the enzyme. The DNA thus accumulated within the enzyme is accommodated as single-stranded bulges.

TLS Online TPP Program

#Id: 2296

#Unit 3. Fundamental Processes

Three general models were proposedfor abortive transcription.