Hemlock (Cicuta sp.) produces cicutoxin, a polyacetylene that prolongs the repolarization of neuronal action potentials.

TLS Online TPP Program

#Id: 6462

#Unit 3. Fundamental Processes

A typical gene transcribed by RNA polymerase II has a promoter that extends upstream from the site where transcription is initiated.

TLS Online TPP Program

#Id: 6463

#Unit 3. Fundamental Processes

A regulatory site that binds more negative regulators than positive regulators to control transcription is called a silencer.

TLS Online TPP Program

#Id: 6464

#Unit 3. Fundamental Processes

Promoters that are constitutively expressed and needed in all cells (their genes are sometimes called housekeeping genes) have upstream sequence elements that are recognized by ubiquitous activators.

TLS Online TPP Program

#Id: 6465

#Unit 3. Fundamental Processes

Proteins bound at enhancer elements interact with proteins bound at promoter elements via DNA looping, very often through intermediates called coactivators.

TLS Online TPP Program

#Id: 6466

#Unit 3. Fundamental Processes

Eukaryotic transcription is most often under positive regulation: A transcription factor is provided under tissue-specific control to activate a promoter or set of promoters that contain a common target sequence.

TLS Online TPP Program

#Id: 6467

#Unit 3. Fundamental Processes

There are five common subunits in all three RNA Polymerases

Rpb5

Rpb6

Rpb8

Rpb10

Rpb12