Chapter 14 Flashcards
(34 cards)
Conserves energy
Proteine produce as needed
Constitutive gene
Unregulated & have essentially constant levels of expression
Bacterial gene regulation
Occurs at Transcription leve/or Control mRNA translation rate, or regalate proteine.
Eukaryotic gene regulation
Transcriptional regulation, RNA processing, translation, post- translation
Repressors
Inhibit Transcription
negative control
Activators
Increase the rate of Transcription
positive Control
Small effector molecole
Binds to regulate Transcription factor & cause conformational change
2 domains in regulatory Transcription factors.
Site where protein binds to DNA
Site for small effetto molecole
Operon
in batteria.
A cluster of genes under transcriptional Control of One promoter.
Polycistronic mRNA
Encodes more than 1 protein.
Lac operano
in e.coli
Contains lactose metabolism genes
LacP
Promoter
3 structural genes
Lac Z -β-galactosidase (enzyme)
Lac y- lactose permease (transporter)
Lac A- galactosidase transacetylase (modifies lactose)
LacO- operator-
Provides building site for Repressor protein
CAP site
Activator protein binding site
LacL gene-
Codes for lac Repressore
In absent of lactose
Lac repressor protein binds to nucleotide, prevents RNA polymers from transcribing LacZ,LacY,LacA
When lactose is present
4 allolactose molecules binds to Lac repressor prevents repressor from binding
CAP ( catabolite activator protein)
An activator protein
When lactose & glucose are high
Lac operon is shut off
When lactose is high & glucose is low
Lac operon is turned on
When lactose is low & glucose is high / low
Lac operon is off
Low tryptophan level
Trp repressor can’t bind & operon genes transcribed
High tryptophan levels.
Tryptophan turns off the trp operon
