Chapter 12
Gene Transcription and RNA Modification
Study Outline
I. Overview of Transcription
A. Gene expression requires base sequences that perform different functional roles
B. The three stages of transcription are initiation, elongation, and termination
C. RNA transcripts have different functions
II. Transcription in Bacteria
A. A promoter is a short sequence of DNA that is necessary to initiate transcription
B. Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a
promoter sequence
C. The RNA transcript is synthesized during the elongation stage
D. Transcription is terminated by either an RNA-binding protein or an intrinsic terminator
III. Transcription in Eukaryotes
A. Eukaryotes have multiple RNA polymerases that are structurally similar to the bacterial
enzyme
B. Eukaryotic structural genes have a core promoter and regulatory elements
C. Transcription of eukaryotic structural genes is initiated when RNA polymerase II and
general transcription factors bind to a promoter sequence
D. Transcription termination of RNA polymerase II occurs after the 3’end of the transcript is
cleaved near the polyA signal sequence
IV.
RNA Modification
A. Some large RNA transcripts are processed into smaller functional transcripts by
enzymatic cleavage
B. Introns were experimentally identified via microscopy
C. Different splicing mechanisms can remove introns
D. Pre-mRNA splicing occurs by the action of a spliceosome
E. The ends of eukaryotic pre-mRNAs have a 5' cap and a 3' tail
F. The nucleotide sequence of RNA can be modified by RNA editing