Transcription in Eukaryotes Practice Flashcards

This set of vocabulary flashcards covers the key proteins, DNA regions, and molecular mechanisms involved in eukaryotic transcription as described in the lecture notes.

Monocistronic mRNA

A type of mRNA characteristic of eukaryotes where only one region is translated into a protein.

5’ UTR and 3’ UTR

Untranslated regions that flank the coding region of a gene and may be transcribed but are not translated into protein.

+1 site

The transcription start site, representing the first base of Exon 1 and part of the 5' UTR.

Core Promoter

A highly conserved sequence that acts as the “ON /OFF” switch; it is the binding site for General Transcription Factors and RNA Pol II.

Proximal Promoter

A region containing regulatory sequences that bind transcriptional activator proteins (Specific Transcription Factors) to stabilize RNA Pol II.

TATA box

A consensus sequence signature ($TATAAA$) found in the core promoter regions of approximately 25% of human genes.

TBP (TATA binding protein)

A General Transcription Factor required for transcription that recognizes and binds to the TATA box.

Specific Transcription Factors

Regulatory proteins that bind to the proximal promoter and distal regions like enhancers or silencers to influence transcription initiation.

RNA polymerase I

The eukaryotic enzyme responsible for transcribing large rRNAs.

RNA polymerase II

The eukaryotic enzyme responsible for transcribing pre-mRNA, some snRNAs, snoRNAs, and some miRNAs.

RNA polymerase III

The eukaryotic enzyme responsible for transcribing tRNAs, small rRNAs, some snRNAs, and some miRNAs.

Enhancers and Silencers

Distal regulatory regions that may be thousands of bp away from the transcription start site and bind activators or repressors.

TFIID Complex

A complex containing TBP that recognizes the TATA box and recruits general transcription factors for recognition and initiation.

TFIIB

A General Transcription Factor involved in initiation that stabilizes the TFIID complex and recruits RNA Pol II to the core promoter.

TFIIH

A factor with helicase activity that opens the transcription bubble and kinase activity that phosphorylates the CTD tail of RNA Pol II.

Mediator Complex

A complex that bridges specific transcription factors bound at distal regions with the RNA Pol II Holoenzyme at the core promoter.

CTD Tail (Carboxyl-terminal Domain)

The end of the RNA Pol II protein that must be phosphorylated by TFIIH to activate the holoenzyme for elongation.

Pre-Initiation Complex (PIC)

A complex formed by RNA Pol II loaded with general transcription factors, the mediator complex, and DNA ready for initiation.

Elongation Factors (EFs)

Proteins that evict histones ahead of RNA Pol II and replace them behind it, maintaining the heteroduplex RNA:DNA hybrid region.

Minimal Initiation Complex (MIC)

The initial assembly of TFIID, TFIIB, and RNA Pol II at the core promoter.