Transcription

1) Initiation

• Transcription Factors assemble on the promoter region (TATA box)
• RNA polymerase II binds to the transcription factors (transcription initiation complex)

2) Elongation

• Moving from 5' to 3', RNA polymerase synthesizes a strand of pre-mRNA that is complimentary to the template strand of DNA
• Template strand (antisense strand)- the sequence of DNA that is copied 
• Coding strand (sense strand)- the sequence that corresponds with 
• Pre-mRNA strand, Thymine is replaced with Uracil 

3) Termination

• RNA polymerase II reaches the terminator sequence (AAUAA), transcription stops
• Pre-mRNA is removed
• Pre-mRNA protected by G cap (guanine) on the 5' side and poly A tail on the 3' side
• RNA splicing 
• Introns (non-coding regions) - are removed from pre-mRNA
• Exons (coding regions) - join to form the mature mRNA
• snRNA + snRNP(proteins) - recognizes regions where exons and introns meet
• snRNP interact with other proteins = larger spliceosome complex that removes introns
• mRNA strand is complete and ready to transport to the ribosomes (factory)