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TRANSCRIPTION Dr. Harinikumar. K.M. University of Agricultural sciences Bengaluru Karnataka. www.powerpointpresentationon.blogspot.com. The Central Dogma. The central dogma of molecular biology was first articulated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970
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The central dogma of molecular biology was first articulated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970
The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.
In other words, the process of producing proteins is irreversible: a protein cannot be used to create DNA.
FIGURE :Promoters and terminators define the unit
Promoter –A region of DNA where RNA polymerase binds to initiate transcription.
Initiation RNA pol I RNA pol III RNA pol II
ATP requirement no no yes
A and B or TATA box
core consensus sq. core element C box Inr
upstream element UCE GC box etc
general TFs SL1 TFIIIA B C various TFIIs
upstream factors UBF various up-
FIGURE : RNA polymerase has 4 types of subunit
Rifampicin, a therapeutic drug for tuberculosis treatment, can bind specifically to the subunit of RNA-pol, and inhibit the RNA synthesis.
Site of DNA binding and RNA polymerization
FIGURE : Sigma factor controls specificity
Generally, bacteria that live in more varied environments have more sigma factors
Extreme heat shock, unfolded proteins
E. coli can choose between 7 sigma factors and about 350 transcription factors to fine tune its transcriptional output
FIGURE :- RNA polymerase surrounds the bubble
FIGURE RNA synthesis occurs in the transcription bubble
Individual promoters usually differ from the consensus at one or more positions.
FIGURE 14: DNA elements and RNA polymerase modules contributing to promoter recognition by sigma factor
RNA polⅡ with transcription factors form transcription initiation complex. TF II D is the only factor which can recognize specific sites.
Pre initiation complex
CTD（Carboxyl Terminal Domain ) is repeated sequence of Tyr-Ser-Pro-Thr-Ser-Pro-Ser
CTD tail of RNA pol II is phosphorylated by TFⅡH
FIGURE :-Sigma and core enzyme must dissociate
FIGURE :- DNA turns at the active site
FIGURE :- Rho can terminate when a nonsense mutation removes ribosomes
FIGURE :- Transcription changes DNA structure
FIGURE :- Sigma controls promoter recognition
FIGURE :- E. coli has several sigma factors