__, the carrier of information from DNA to the cell’s protein-synthesizing machinery, is transcribed from the template strand of a gene.
An enzyme called __pries the two strands of DNA apart and joins the RNA nucleotides as they base-pair along the template.
· Can assemble a polynucleotide only in the __ direction.
· Unlike DNA pol, they do not need a __.
Specific sequences of nucleotides along the DNA mark where __of a gene begins and ends.
The DNA sequence where __ attaches and initiates __is known as the __; in bacteria, the sequence that signals the end of transcription is the __.
Molecular biologists refer to the direction of transcription as “__” and the other direction as “__”.
· Terms also used to describe the positions of nucleotide sequences within the DNA or RNA.
· Thus, the __sequence in DNA is said to be upstream from the __.
The stretch of DNA that is transcribed into an RNA molecule is a __.
Bacteria have a single type of __ that synthesizes not only __ but also other types of RNA that function in protein synthesis.
Eukaryotes have at least three types of __in their nuclei.
· The one used for mRNA synthesis is __.
· The other __transcribe RNA molecules that are not translated into protein.
RNA pol II
The three stages of transcription are __, __, and __.
initiation, elongation, and termination of the RNA chain.
The promoter of a gene includes within it the __(the nucleotide where RNA synthesis actually begins) and typically extends several dozen nucleotide pairs __ from the start point.
transcription start point
Besides serving as a binding site for __ and determining where transcription starts, the __determines which of the two strands of the DNA helix is used as a template.
Certain sections of a __are important for binding RNA pol.
· Bacteria: __ itself specifically recognizes and binds to the __
Eukaryotes: collection of proteins (__) mediates the binding of RNA pol and the initiation of transcription.
o Only after certain __ are attached to the __ does __ bind to it.
transcription factors x2
RNA pol II
The whole complex of ___ and ___ bound to the promoter is called a ___.
o __: a nucleotide sequence containing TATA, about 25 nucleotides upstream from the transcriptional start point; a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
RNA polymerase II
transcription initiation complex
The interaction between eukaryotic __ and __ is an example of the importance of protein-protein interactions in controlling eukaryotic transcription.
Once the pol is firmly attached to the __ DNA, the two DNA strands unwind there, and the enzyme starts transcribing the template strand.
RNA pol II and transcription factors
As __moves along the DNA, it continues to untwist the double helix.
The enzyme adds nucleotides to the __ end of the growing RNA molecule as it continues along the double helix.
The new RNA molecule peels away from its DNA template and the DNA double helix reforms.
A single gene can be transcribed simultaneously by several molecules of __ following each other.
A growing strand of RNA trails off from each polymerase, with the length of each new strand reflecting how far along the template the enzyme has traveled from the start point.
The congregation of many polymerase molecules simultaneously transcribing a single gene increases the amount of __transcribed from it, which helps the cell make the encoded protein in large amounts.
True or False:
The mechanism of termination differs in bacteria and eukaryotes:
Bacteria: transcription proceeds through a __in the DNA. The transcribed terminator (__) functions as the __ , causing the polymerase to detach from the DNA and release the transcript, which is available for immediate use as mRNA.
Eukaryotes: __transcribes a sequence on the DNA called the __, which codes for a __ in the pre-mRNA. Then, at a point about 10-35 nucleotides downstream from the __, proteins associated with the growing RNA transcript cut it free from the polymerase, releasing the pre-mRNA. However, the polymerase continues transcribing DNA for hundreds of nucleotides pas the site where the pre-mRNA was released.
RNA pol II
polyadenylation signal sequence
polyadenylation signal (AAUAAA)
Research on yeast cells suggest that the RNA produced by this continued transcription is digested by an enzyme that moves along the RNA.
· Data supports idea that when the enzyme reaches the __, __is terminated and the polymerase falls off the DNA. Meanwhile, the pre-mRNA undergoes processing.