RNA polymerase σ α 2 ββ’ Core enzyme σ promoter DNA α 2 ββ’ Transcription in Procaryotes.

RNA polymerase

σ

α2ββ’ Core enzyme

σ promoter

DNA

α2ββ’ α2ββ’

Transcription in Procaryotes

RNA polymerase

σ

α2ββ’ Core enzyme

σ promoter

DNA

α2ββ’ α2ββ’

σ factor ： rpoD

rpoH

rpoN…等

Regulation

Figure 9.03

Heat shock proteins

lac operon

araBAD operon

What do we mean by the 5´ end of a gene?

• Since DNA has two antiparallel strands it has no actual polarity.

• mRNA does have polarity since it is single stranded. The 5´ end refers to the mRNA molecule and since it is copied from the DNA by standard base pairing the 5´ end of a gene is the 3´ end of the template strand.