regulation of gene expression Flashcards
regulatory elements
DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences
constitutive expression
continuously expressed under normal cellular conditions (housekeeping genes)
positive control
stimulate gene expression
-works with activator
negative control
inhibit gene expression
-works with repressor
domains
-60-90 amino acids
-responsible for binding to DNA
-forms hydrogen bonds with DNA
motif
within the binding domain, a simple structure that fits into the major groove of the DNA
operon
promoter + additional sequences that control transcription + structural genes
regulator gene
DNA sequence encoding products that affect the operon function but are not part of the operon
inducible operons
transcription is usually off and needs to be turned on by an activator
activator
protein that binds to the enhancer to promote transcription
inducer
small molecule that binds to repressor protein causing it to detach from DNA, allowing transcription to occur
repressible operons
transcription is usually on and needs to be turned off by a repressor, so the transcript is repressible
repressor
protein that inhibits gene expression by binding to DNA and blocking transcription
corepressor
small molecule that binds to the repressor and increases its ability to suppress gene expression
riboswitches
RNA sequences in mRNA that affect gene expression
-transcriptional vs translational
attenuation
this action terminates the transcription before it completes synthesis of the genes full ORF within the mRNA
-affects the continuation of transcription, not its initiation
ribozymes
when bound by small regulatory molecules, can induce the cleavage and degradation of mRNA, RNA mediated repression
histone modification
methylation or acetylation
-change accessibility of certain genes
chromatin remodeling
DNA methylation
typically represses gene expression by adding methyl groups to DNA
-alters how DNA reacts with other proteins and can potentially prevent transcription factors from binding
histone acetylation
promotes gene expression by adding acetyl groups to histones
-can loosen the chromatin structure, making DNA more accessible for transcription
consensus sequence
order of most frequent residues or most common & best bound sequence
promoters of each gene respond to
a unique combination of transcription factors
transcription factors bind to
different consensus sequences
enhancer
DNA sequence that increases transcription of a specific gene
