DNA Transcription

Transcription: synthesis of RNA from a DNA template

The RNA transcript (single stranded) is also called pre-mRNA or primary RNA.

Part I: Initiation 
1. Initiation complex
 --> Transcription factors: set of proteins that help RNA recognize and bind to promoter
 --> RNA Polymerase II: unzips the double helix and makes the RNA copy
2. Promoter (TATA box)
--> Promoter Region: attracts TF and "TATA" box, indicates where RNA Polymerase complex should bind to initiate transcription

Part II: Elongation
3. Polymerase II
--> template/ antisense strand (RNA is anti-parallel to this strand. If the RNA intersects an unknown strand, it is the template/antisense strand)
--> coding/sense strand (5' to 3') (RNA is parallel and similar to this strand)
--> replace T with U (Uracil) on RNA strand because RNA hates "T" but loves "U" C:

Part III: Termination
4. Terminator (AAUAA box)
5. G-Cap and Poly A tail (...AAAAAAA...)
--> G-Cap: signals attachment of ribosome, capped with m^7G (methylated guanosine)
--> Poly-A tail: protects mRNA from degration
6. Splicosome
--> snRNA: recognizes the sequence of introns
--> snRNP: protein that contains snRNA
--> a loop of introns are made and is then cut by the splicosome
--> the splicosome also reconnects the exons before leaving
7. Introns/ Exons
--> Introns: USELESS INFORMATION
--> Exons: USEFUL INFORMATION

Upstream: Promoter Region
Downstream: Everything after Promoter Region