Save
Busy. Please wait.
Log in with Clever
or
show password
Forgot Password?
Don't have an account?  Sign up 
Sign up using Clever
or
Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account. Your email address is only used to allow you to reset your password. See our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
focusNode
Didn't know it?
click below
 
Knew it?
click below
Don't Know
Remaining cards (0)
Know
0:00
edit
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Transcription Part 1

Transcription I

QuestionAnswer
How does RNA polymerase read the template strand? In the 3' to 5' direction and produces a transcription in the 5' to 3' direction identical in the the sequence to the bottom coding strand
What does unwinding DNA do? Create a transcription bubble (Chromatin has to undergo chromatin remodeling)
What does SSB do? Prevents reannealing
What needs to be recognized for transcription to occur and what needs to be present in the proceeding nt? Promoter has to be recognized and a 3' OH needs to be on the proceeding nt for continued polymerization
What happens to the incoming nucleoside triphosphate? At the alpha, the 3'OH undergoes a nucleophillic attack of incoming NTP.
After reaction occurs what is released? Pyrophosphate (PPi) which almost instantaneously cleaved into 2 inorganic phosphates (Pi) thereby driving the reaction irreversibly
What does the prokaryotic system transcription require? Requires assembly of a # of polypeptide chains
E. Coli RNA polymerase subunits alpha=holoenzyme assembly; initiation. beta=Nucleotide binding; chain initiation & elongation, 5'-3' RNA synthesis. b'=binding to DNA template(strong affinity for DNA, helps b latch on) sigma=recog & binding to promoters; open promoter complex
When can sigma be discarded? At point of initiation, only core needed for elongation & termination
RNA polymerase I 14 subunits, nucleolus, produces rRNA precursors, resistant to inhibition by alpha-amanitin.
RNA polymerase II 12 subunits, nucleus, precursor to mRNA, sensitive to alpha-amanitin
RNA polymerase III 17 subunits, nucleus, synthesizes 5SrRNA, tRNA & small RNAs, moderated sensitivity to alpha-amanitin
What do all 3 RNA polymerase have in common? All 3 have a common large subunit (lots of resemblance to B & B' of Pro)
Large subunit of RNA polymerase II At the C terminus domain, there is a repeat 7-amino acid peptide: CTD domain; 2 large subunits=claw like, small subunits cluster on the periphery of large subunits
Termination rho-independent rho-independent: does not require rho factor, intrinsic secondary structure (stem-loop) that is created by newly synthesized RNA. Induces RNA pol to pause. Stem loop is rich in GC residues followed by poly U tract.
Inhibitors of Transcription Actinomycin D: Both Pro & Euk, intercalator b/w G & C. Rifampicin: blocks B subunit in Pro system. Alpha-amantinin: inhibits RNA pol II in Euk
What does the 5' cap structure enable in Euk? Enables mRNA to be recognized by the initiation factor eIF-4F. Cap contributes to the integrity & stability of mRNAs by protecting the 5' ends from attack by phosphatases & %' exonucleases
Describe the process of polyadenylation Poly A tail is added post-transcriptionally to 3' end of Euk mRNA by poly A polymerase. Site of polyadenylation is determined by the hexanucleotide AAUAAA.
What does polyadenylation do? Enhances mRNA stability by protecting it against degradation mediated by 3' exonuclease. It has been postulated to aid in mRNA transport from nucleus to cytoplasm (histone mRNAs lack a poly A-tail)
RNA editing Introns are removed
How is rRNA transcript in Prokaryotes synthesized? As a longer precursor of 30S: contains rRNA-16S, 23S & 5S rRNA
How is rRNA transcribed in Eukaryotes? 35S & 47S (larger precursor)- 18S, 28S and 5.8S
How is tRNA spliced? BY RNase P which is an endonuclease that recognizes tertiary structures of primary transcript to effect change at 5' end of the tRNA precursor.
What does mature tRNA contain? CCA at the 3' end
What happens if CCA is in sequence and not at 3' end? RNase D is required to cleave til CCA is at the 3' end
What happens if CCA is not present? It may be generated post-transcriptionally by the enzyme tRNA nucleotidyl transferase in a reaction that uses 2 molecules of CTP & one molecule of ATP
Popular Biochemistry sets

 

 



Voices

Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!
"Know" box contains:
Time elapsed:
Retries:
restart all cards