module 8 Flashcards
gene regulation
the level of gene expression can vary under different conditions
constitutive
genes that are unregulated
gene regulation is important for cellular processes such as
metabolism, response to environmental stress, cell division
common points of gene regulation in transcription
- gene regulatory proteins bind to the DNA and control the rate of transcription
- formation of a transcriptional terminator ends transcription shortly after it’s begun
common points of gene regulation in translation
- translational repressor proteins can bind to the mRNA
- riboswitches can produce a mRNA conformation
- antisense RNA can bind to the mRNA
Repressors
bind to the DNA and inhibit transcription
common points of gene regulation in posttranslation
- feedback inhibition product inhibits first enzyme in the pathway
- covalent modifications to the structure of a protein
activators
bind to DNA and increase transcription
negative control
transcriptional regulation by repressor proteins
positive control
transcriptional regulation by activator proteins
small effector molecules that increase transcription
bind to activators and cause them to bind to DNA, bind to repressors and prevent them from binding to DNA
genes that are regulated with positive SEMs (inducers) are termed
inducible
small effector molecules that inhibit transcription
corepressors bind to repressors and cause them to bind to DNA
inhibitors bind to activators and prevent them from binding to DNA
genes that are regulated with negative SEMs (compressor) are termed
repressible
repressor protein + inducer molecule =
inducible gene
activator protein + inducer molecule =
inducible gene
repressor protein + corepressor molecule =
repressible gene
activator protein + inhibitor molecule =
repressible gene
enzyme adaption
a particular enzyme appears in the cell only after the cell has been exposed to the enzyme’s substrate
operon
a regulatory unit consisting of a few protein-coding genes under the control of one promoter
polycistronic mRNA
encoded by operon, contains the coding sequence for two or more protein-encoding genes
promoter
binds to RNA polymerase
operator
binds the lac repressor protein
CAP site
binds the Catabolite Activator Protein