Prokaryotic Transcription

• How is the E. coli genome packaged inside the cell?

  It is organized into loops and supercoiled.
• What are the two strands of DNA in a gene called?

  Coding strand and template strand
• What is the role of the main promoter elements in E. coli?

  They interact with RNA polymerase to initiate transcription.
• What is the process of transcription in prokaryotes?

  It is the synthesis of RNA from a DNA template.
• What do intrinsic and Rho dependent terminators do?

  They terminate the transcription process.
• What is the nucleoid in bacteria?

  The bacterial equivalent of the nucleus, not membrane-bound.
• How is the bacterial genome organized?

  It is organized into loops and supercoiled structures.
• What is the size range of loops in bacteria?

  10 - 50 kb
• How does supercoiling help DNA in bacteria?

  It allows the DNA to coil up on itself, fitting into a small space.
• What is the relationship between the coding strand and mRNA?

  mRNA is identical in sequence to the coding strand, with U replacing T.
• What is a gene?

  A region of double-stranded DNA that encodes a peptide chain (protein).
• What do the sequences of G, A, T, and C in DNA represent?

  Instructions that encode the protein.
• What is the role of tRNA and rRNA?

  They are involved in translation to produce proteins.
• What is the significance of the translational start codon (AUG)?

  It indicates the start of protein synthesis and always codes for Methionine.
• What is an untranslated region (UTR)?

  Regions of mRNA that do not encode protein.
• How is RNA synthesized in relation to DNA?

  RNA is always synthesized in the 5’ to 3’ direction.
• What is the role of the promoter in gene transcription?

  It is the control region found at the start of the gene where transcription begins.
• What is the terminator in transcription?

  The sequence found at the end of the gene that signals termination.
• What does it mean for mRNA to be synthesized from promoter to terminator?

  It indicates the direction of information flow through the gene.
• What is a polycistronic mRNA?

  It encodes more than one protein.
• What is an operon?

  A cluster of genes transcribed from one promoter.
• How does RNA polymerase know where to bind?

  By recognizing consensus sequences in the promoter region.
• What are consensus sequences?

  Common bases observed at specific areas in the DNA sequence.
• What is the significance of the -10 and -35 sequences in prokaryotic promoters?

  They are conserved elements that help RNA polymerase bind and initiate transcription.
• What happens during RNA synthesis?

  RNA polymerase synthesizes RNA in the 5’-3’ direction without a primer.
• What is the active site of RNA polymerase?

  It is where the RNA-DNA hybrid of 9 bp is formed during transcription.
• What is coupled transcription/translation in bacteria?

  It is when transcription and translation occur simultaneously in the cytoplasm.
• What are intrinsic terminators?

  They are terminators that contain all the information needed for termination within the gene itself.
• How do Rho-dependent terminators function?

  Rho binds to the rut site in mRNA and unwinds the RNA-DNA hybrid to terminate transcription.
• What is the role of the rut site in Rho-dependent termination?

  It is a sequence rich in C and poor in G that Rho recognizes to interact with the RNA.
• What happens when Rho catches up with RNA polymerase?

  Rho unwinds the RNA-DNA hybrid, leading to the termination of transcription.