Gene Expression *Protein coding gene *Gene expression Genes control inherited variation via: DNA,...

Gene Expression

*Protein coding gene

*Gene expression

Genes control inherited variation via:

DNA, RNA and protein

Phenotype

*Gene

DNA PhenotypeRNA ProteinReplication TranscriptionTranslation

Brief overview of transcription:

Transcription*RNA polymerase (from E. coli )

2 ’

CoreSigma factor

Holoenzyme

Transcription

Functions of a prokaryotic promoter:

1. ON/OFF Switch

2. Speed Switch

3. Alignment

Binding of RNA Polymerase to Promoters

How tightly does core enzyme vs. holoenzyme bind DNA?

Transcription Initiation

Transcriptional Elongation:

Termination of TranscriptionInverted Repeats and Hairpins

• The repeat at right is symmetrical around its center shown with a dot

• A transcript of this sequence is self-complementary– Bases can pair up

to form a hairpin as seen in the lower panel

Termination of Transcription

*Rho-independent termination

factor

Termination of Transcription*Rho-dependent termination