The inherent leakiness of the sinus nodal fibers to sodium and calcium ions causes their self-excitation.

TLS Online TPP Program

#Id: 6309

#Unit 3. Fundamental Processes

In hydrolytic editing, the polymerase backtracks by one or more nucleotides and cleaves the RNA product, removing the error-containing sequence. 

TLS Online TPP Program

#Id: 6310

#Unit 3. Fundamental Processes

in E. coli, GreA and GreB enable the polymerase to cleave a few ribonucleotides from the 3’ terminus of the RNA product, thereby allowing the catalytic site of RNA polymerase to be realigned with the 3’–OH to release stalled polymerase

TLS Online TPP Program

#Id: 6311

#Unit 3. Fundamental Processes

he consequences of arrest can be catastrophic if the gene being transcribed is essential as no product will be made by the arrested polymerase, and that same enzyme will cause a roadblock to other polymerases attempting to transcribe the same gene.The cell has machinery that removes the arrested polymerase and at the same time recruits repair enzymes (in particular, the endonuclease Uvr(A)BC); the repair that follows is called transcription-coupled repair. Both polymerase removal and repair enzyme recruitment are performed by a single protein called TRCF.

TLS Online TPP Program

#Id: 6312

#Unit 3. Fundamental Processes

TRCF has an ATPase activity. 

Base-pairing of something to the transcript to destabilize RNA-DNA hybrid

Causes hairpin to form

Causing the transcription to pause

Causes a string of U’s to be incorporated just downstream of hairpin

TLS Online TPP Program

#Id: 6313

#Unit 3. Fundamental Processes

Sequence of a Rho-independent terminator

TLS Online TPP Program

#Id: 6314

#Unit 3. Fundamental Processes

There are 1100 sequences terminators in the E. coli genome

Intrinsic terminators include palindromic regions that form hairpins varying in length from 7 to 20 bp. The stem-loop structure includes a G-C–rich region and is followed by a run of 7U residues.