RNA Polymerase
This detachable subunit directs the core enzyme to specific promoter sequences, enabling accurate transcription initiation.
What is the σ (sigma) factor?
This DNA site, bound by a nucleoid‑associated protein during rapid growth, bends promoter DNA to enhance rRNA transcription.
What is a FIS site?
This RNA structure forms when the ribosome stalls on the leader peptide, preventing the formation of the terminator hairpin and allowing transcription to proceed.
What is the antiterminator hairpin?
This type of transcriptional control occurs when a regulatory protein binds DNA and blocks RNA polymerase from initiating transcription.
What is negative control?
This enzyme charges tRNAs by attaching the correct amino acid using ATP, forming aminoacyl‑tRNA.
What is aminoacyl‑tRNA synthetase?
This subunits role includes assembling the core enzyme and helping recognize upstream promoter elements through interactions with transcription factors.
What is α (alpha)?
This promoter feature, located upstream of the –35 element, strengthens RNA polymerase binding by interacting with the α‑CTD of the enzyme.
What is the UP element?
This RNA structure forms when the ribosome does not stall, causing RNA polymerase to disengage before reaching the structural genes.
What is the terminator hairpin?
This type of control requires a regulatory protein to bind DNA and help RNA polymerase attach to the promoter.
What is positive control?
This special tRNA carries a modified methionine and is the first to enter the P‑site of the ribosome.
What is fMet‑tRNAᶠᴹᵉᵗ?
This subunit provides the DNA‑binding clamp that grips the template strand and is essential for maintaining the transcription bubble.
What is β′ (beta‑prime)
This term describes the minimal DNA sequence required for accurate transcription initiation, including the –35 and –10 elements.
What is the core promoter?
This operon uses attenuation to regulate tryptophan biosynthesis by coupling transcription to translation in real time.
What is the trp operon?
This protein class binds operators to prevent transcription until an inducer removes them.
What are repressors?
These three factors help assemble the 30S initiation complex before the 50S subunit joins.
What are IF‑1, IF‑2, and IF‑3?
This AT‑rich promoter region is where RNA polymerase first melts the DNA to form the open complex.
What is the –10 element (Pribnow box)?
This is the exact nucleotide where RNA polymerase begins adding ribonucleotides to form the first phosphodiester bond.
What is the +1 transcription start site?
This type of termination relies on a GC‑rich RNA hairpin followed by a run of uracils that destabilizes the RNA–DNA hybrid.
What is rho‑independent termination?
This protein class binds activator sites to enhance RNA polymerase recruitment, often responding to low-energy signals like cAMP.
What are activators?
This ribosomal RNA catalyzes peptide bond formation between amino acids.
What is 23S rRNA (peptidyl transferase)?
This transition occurs when RNA polymerase unwinds ~13 base pairs of DNA to expose the template strand for transcription.
What is open complex formation?
his DNA region sits just downstream of the promoter and serves as the binding site for a repressor that can block RNA polymerase progression.
What is the operator?
This type of termination depends on polymerase pausing, giving a helicase time to catch up and release the transcript.
What is rho‑dependent termination?
This molecule binds a repressor and enables it to attach to the operator, shutting down transcription.
What is a corepressor?
These proteins recognize stop codons and trigger hydrolysis of the completed polypeptide.
What are release factors (RF‑1, RF‑2)?