Gene Regulation: Eukaryotes• Levels of Control• Genome Differences:
Prokaryote vs Eukaryote• Gene Regulation• Gene Dosage • Gene Amplification • Heterochromatin and DNA
methylation• Transcriptional Factors• Differential processing • Translational control
Levels of Control
• Transcriptional Control
• Processing • Transport • Translational Control • Ex: Globin synthesis
Genome Differences: Prokaryote vs Eukaryote
• monocistronic (though some nematodes have polygenic mRNA)
• exons and introns• histones and packaging • no simultaneous
transcription and translation
• Gene Dosage • Gene Amplification
Heterochromatin and DNA methylation
•Xic (1 Mb in length) and Xist (lacks an ORF)•Not translated•RNA product•Coats chromosome•Counting?•Progeny cells?
X-chromosome inactivation Gene Dosage compensation
Histones
•Change in chromatin structure•Lysine residues in histones•Histone acetyl Transferases (HAT)•Histone deacetylases
+Acetate group
Promoters: Pro vs Euk
Base level of transcription
Transcriptional Control: Cis Factors
• DNA Sequences• TATA box • Enhancers
•Cis acting elements•Enhancers: upstream/downstream•Can be inserted into the gene•Tissue specific
Mutations
Enhancers
Trans Factors
• Proteins: receptor complex
• Binding domains: DNA & Protein binding areas
Helix-turn-helix
Trans FactorsMajor groove of DNA
zinc fingers and leucine zipper looping of DNA
Example: Steroids
Alternative gene splicing
Differential processing
Humans and Chimps
Translational control
• mRNA stability• ½ life and turnover• Feedback inhibition