Gene Transcription & RNA modification (part 2) Flashcards
After ________ is assembled into its six subunits it binds loosely to the DNA & slides along the DNA looking for the promoter
RNA polymerase holoenzyme
Once the RNA polymerase holoenzyme finds the promoter what happens?
The sigma factor recognizes both the -35 & -10 sequences & its helix turn - helix motif allows it to bind tightly to those sequences
Describe the initiation process in bacterial transcription?
- Holoenzyme scans DNA & sigma factor recognizes promoter & binds tightly to it
- A close complex is formed
- Short RNA is made in the open complex where the sigma factor is released
- Core enzymes elongates
The process of _________ is initiated when the sigma factor within holoenzyme binds to the promoter to form a closed complex
Transcription
In the ________ the strand of DNA in the promoter region are not separated
Closed Complex
So to actually begin transcription in bacteria what must happen?
The double-stranded DNA must be unwinded by DNA helicase to form a open complex
Where does the unwinding of DNA begin at?
The TATAAT or TATA box region because its easier to break A-T bonds since it only has 2 hydrogen bonds
Sigma binding occurs in the ________ where the DNA is still double stranded
Close complex
TATA box unwinding occurs in the ________ to actually start transcription
Open complex
__________RNA is made in the open complex & when the sigma factor is released initiation ends
Nascent RNA
The RNA transcript is synthesized during __________ stage
Elongation Stage
The mRNA is made in the ________ direction with no proof reading
5’ to 3’ direction
Template strand
DNA strand that is used as a template for RNA synthesis (antisense strand)
Coding Strand
Strand being formed by using the template strand (sense strand & uses U instead of T)
RNA follow what base rules?
A-U & G-C
The template strand is read in the 3’ to 5’ direction but mRNA is made in the __________ direction
5’ to 3’ direction
The location of the template strand can affect the ______ mRNA is made where if the top strand is the template strand then it is made from right to left but if the bottom strand is use then its made from left to right ( so transcription can occur in opposite directions)
Direction
Transcription is terminated by either an __________ or a ___________
RNA binding protein or intrinsic terminator
Describe the elongation stage
- RNA polymerase slides along the DNA creating an open complex as it moves
- The template strands is used to make complementary copy of RNA as RNA-DNA hybrid
- RNA polymerase moves along the template strand in a 3’-5’ direction & mRNA is made in the 5’-3’ direction
_________ occurs when the short RNA-DNA hybrid region is forced to separate & release new mRNA & RNA polymerase
Termination