Transcription

What is Transcription?
1. A section of DNA is decoded to create proteins, to create RNA
Differences from DNA Replication
1. Does not use SSB proteins
2. Only small section of DNA strand is broken
3. The RNA nucelotides have different sugar and uracil replaces thymine
  1. Also single stranded
4. No Helicase needed
What are the sequence of events?
1. Elongation
  1. The RNA Polymerase causes the alpha subunit of ribose to phosphodiester bond with -OH on the 3rd carbon. A pyrophosphate is lost
    1. The RNA polymerase breaks open the RNA strand at -10 box
2. Initiation
  1. Eukaryotes
    1. Uses TATA box
    2. Uses TF's (DABFEH)
    3. RNA Polymerase II
  2. Prokaryotes
    1. Uses -35, -10 and +1 Box
    2. RNA Polymerase attaches to the promoter region covering from -35- +1
3. Termination
  1. A terminator region is reached as a result a stem loop forms. The RNA polymerase gets tangled with the stem loop and broken off
    1. They are palindromes and RNA base pair itself
    2. Factor Row
    3. After this RNA can go straight into translatin
  2. Prokaryotes
  3. Eukaryotes
    1. Pre-RNA is formed and further spliced into RNA
      1. There are three parts to this: Capping, Polyadenylation and Intron Splicing
        Capping
        Guanine bond joined by 5 - 5 prime tri phosphae bond on 5 prime end base of the pre-MRNA
        The guanine is then methylated
        Polyadenylation
        Signal reached, cleaved 10-30 bases downstream, 250 adenine bases added
        Intron Splicing
        Uses snRNP
        OH on 2 prime carbon nucleophilic attack on 5 prime end of intron
        The 5 prime -OH attackes 3 prime intron end of intron and a lariat forms
Structure of RNA Polymerase
1. Made up of five subunits, sigma subunit can detach to create a four subunit core enzyme
2. Sigma subunit tells RNA polymerase where promoter region starts

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