Ch 12 Operons Flashcards
What are regulatory proteins?
Help a cell sense internal changes and alter gene expression to match
What are repressors?
Bind to regulatory sequences are prevent transcription of target genes
What are activators?
Bind to regulatory sequences are stimulate transcription of target genes
Enzymes to metabolize lactose are ________
Inducible (can be caused)
Enzymes to metabolize glucose are _________
Constitutive (exists by its own will)
LacXYZ: What does the LacI do?
Represses lac operon when lactose is absent
LacXYZ: What does LacZ do?
When there are low levels of lactose it cleaves and rearranges it to make allolactose
What happens when LacI and allolactose combine?
Allolactose comes off the operon and starts producing mRNA
What is the importance of cAMP and cAMP receptor protein?
They maximize gene expression by binding to the promoter and RNA pol to increase transciption rate
What does AraC do?
It can repress or activate gene expression
What does AraC look like when arabinose is absent?
It is rigid and elongated
What does AraC look like when arabinose is present?
It is more compact and stimulates binding of RNA pol, transcription
What are trp operons?
Biosynthetic operon encoding enzymes
What is attenuation?
Regulatory mechanism where translation of leader peptide affect transcription of downstream structural gene
