Transcription

Transcription (ie DNA-> RNA)

The 3 processes to Transcription

  1. Initiation
  2. Elongation
  3. Termination

Transcription is the process of DNA being converted to RNA. First, there are several major factors.

Factors Function
RNA Polymerase
  • Builds RNA from half of DNA double helix
  • Builds from 5' to 3'
  • Open and closes the DNA double helix as it goes along
  • Binds to promoter region, not to the coding region
  • Starts at the promoter region but moves along to coding region
  • Does not transcribe promoter region
  • Stops at the termination region
Promoter Region
  • This is a region before the coding region
  • Transcription factor proteins bind to promoter region
  • RNA Polymerase binds here first
  • This region is not transcribed by the RNA Polymerase
Spliceosome
  • Splits the introns from the exons
  • Connects the split exons and discards the introns
5' Cap Marks the beginning of the free mRNA
Poly-A Tail A long chain of "A" nucleotide on the 3' end of the mRNA

Intiation

  1. Transcription factor proteins bind to promoter region on the template strand
  2. RNA Polymerase looks for the transcription factor protein and binds to it

Elongation (Part 1)

  1. The RNA Polymerase starts going down the template strand
  2. It does not transcribe the promoter region proteins
  3. It starts to convert A->U, G->C, T->A, C->G
  4. After converting, the RNA Polymerase falls off after it hits the termination region
  5. At the same time, the single stranded mRNA disconnects from the RNA Polymerase

Elongation (Part 2)

  1. Several spliceosome parts latches on to borders between introns and exons
  2. They then move and connect to each other forming a complete spliceosome
  3. Because each spliceosome now have the exon ends next to each other, they cut out the introns and connect the exons
  4. The freed introns are dissolved back into nucleotides by other proteins to be reused
  5. A 5' cap and a poly-A tail is added to the ends of the spliced mRNA.

Termination (Part 3)

The spliced mRNA is moved out of the nucleus into the cytosome


That's it ¯\_(ツ)_/¯

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