Card Set Information
(key concepts) What does RNA polymerase do? (2)
-binds to specific site in DNA with help of other proteins
-catalyzes production of an RNA
(Key concepts) What happens during RNA processing? (2)
introns are removed
*a cap and tail join the RNA
In what direction is mRNA formed?
It is formed in a 5' to 3' direction
What are the names of the 2 DNA strands?
-non-template strand (coding)
Which side of the DNA strand does the RNA use as a base template?
the template strand
What does the non-template strand do?
it codes for the RNA
What are promoters? (2)
are specific sections of DNA that are initiated during transcription
(bacteria) What are the 2 key regions that promoters have?
- -10 box
*10 bases upstream from transcription start site
- -35 box
* 35 bases upstream from trancription start site
In what direction does the RNA polymerase move during transcription?
WHat needs to happen to initiate transcription?
Σ protein needs to bind to the -10 and -35 boxes properly to orient the RNA polymerase holoenzyme for transcription at the start site
What forms the Holoenzyme? (2)
Σ and RNA polymerase
Where do phosphodiester bonds form in RNA polymerase?
in the active site where channels intersect
(Initiation of transcription in bacteria) step 1 (4)
-where the red thing starts after sigma, that where it starts coding
*then it goes downstream
-sigma binds to promoter regions of DNA
*serves as an anchor
(Initiation of transcription in bacteria) step 2 (2)
-the NTPs flow inside to create the RNA strand by binding nucleotides
-the DNA is being split
(Initiation complete of transcription in bacteria) step 3 (2)
-initiation is complete
- the sigma falls off when elongation process starts
(step 3) is the upstream DNA trasncribed?
(step 3) what does the zipper do?
helps unzip the DNA
(step 3) what does the rudder do?
guides the DNA along
(step 4 of bacteria)(2)
-the trancription termination signal is coming when it is fully red instead of blueish
(Step 5 of bacteria)
-hairpin loop begins to happen whoch signals the end of transcription
(step 6of bacteria) (2)
-mRNA is formed and detaches
-DNA is fully read
(Initiation SUmmary 5 steps of transcription in bacteria) Step 1
- Σ opens the DNA double helix and the template strand is threaded through the RNA polymerase active site
(Initiation SUmmary 5 steps of transcription in bacteria) STep 2
-incoming ribonucleotide triphosphate pairs with a complementary base on the DNA template strand
**RNA polymerazation begins
(Initiation SUmmary 5 steps of transcription in bacteria) step 3
-Σ dissociates from the core enzyme once the initiation phase of transcription is completed
(elongation and termination steps summary in bacteria Transcription) step 1 (2)
-during elongation phase, RNA polymerase moves along the DNA template and synthesizes RNA in 5 to 3 direction
**it is moving downstream
(elongation and termination steps summary in bacteria Transcription) step 2
-transcription ends with a termination phase
* RNA polymerase encounters a transcription termination signal in the DNA template
(elongation and termination steps summary in bacteria Transcription) step 3 (3)
-signal codes for RNA forming a hairpin structure
*causing the RNA polymerase to separate from the RNA transcript
**ending the transcription
(transcription in Eukaryotes) DO the promoters recognized by each type of RNA polymerase differ?
What is a TATA box? (3)
-a promoter that is recognized by RNA polymerase II
-analogous functon to -10 and -35 boxes
-thymadine and adenine
What are exons? (2)
-coding regions of eukaryotic genes that will be part of the final mRNA product
-these are expressed in final transcript
What are introns?
intervening noncoding sequences that are not included in final mRNA
Eukaryotic genes size AND Corresponding mmature mRNA
Genes are much larger because they contained introns and exons
What is the Primary RNA transcript? (2)
-it is the transcription of eukaryotic genes by RNA polymerase
-it contains exons and introns
How are introns removed?
they are spliced out by snRNPs
What are the Small Nuclear ribonucleoproteins? (2)
-form a complex called a spliceosome
-this complex ^ catalyzes the splicing reaction
In Eukaryotes, what are mRNAs given? (2)
a 5' cap and a Poly-A tail
What happens when the mRNA is given the cap and tail? (2)
the processing is complete
*the prodcut is a mature mRNA
What does the 5' cap do? (2)
-provides an anchoring point when it meets up with a ribosome
-recognition signal for the translation machinery
What does the tail do? (2)
-extends the life of an mRNA by protecting it from degradation
-the longer the tail, the longer it stays in cell, and the more proteins it produces