7.2 Transcription 

Initiation

• %%RNA polymerase%% binds to template DNA at promoter (sequence before start of gene) by recognizing TATA (lost of A, T)
• DNA strands are seperated (like helicase)

Elongation

• RNA polymerase synthesizes complementary RNA strands 3’ direction
• no primer necessary
• while DNA is opened, many RNA polymerases may be active synthesizing many RNA strands

Termination

• RNA polymerase recognizes termination sequence and dissociates from DNA
• RNA also dissociates and leaves nucleus via nuclear pores into cytosol

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Post-Transcription Modifications

• RNA known as pre-mRNA
• Must me modified before it can leave the nucleus   * addition of poly-A tail   * prevents degredation
• Removal of introns (non-coding regions) and splicing of exons (coding regions )   * makes mRNA functional   * alternative splicing can produce difference mRNAs from the same pre-mRNA

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