W10 Gene expression regulation Flashcards
what is gene expression normally controlled by in unicellular organisms
environmental changes
how is transcription initiated and regulated in prokaryotes
- at primary control point transcription of operons occurs
- RNA polymerase sigma factor binds to regulatory sequence
what are operons
2 or more genes regulated by a promotor + terminator
how is transcription terminated in cells
after the release of sigma factors and termination via rho protein/stable hairpin
what is the role of tryptophan repressors
switch off genes
what happens when tryptophan is low/high
low = operon is on so more transcription
high = operon is off so no transcription
how can genes be turned on in prokaryotes
activators bind to bound activator proteins
what is the Lac operon
negative inducible operon for lactose regulation
what’s the role of the Lac operon
cleaves lactose into glucose and galactose
what is used by prokaryotic cells glucose or lactose first
glucose
what genes are on Lac operon for lactose regulation
gene Z, Y and A
what condition turns on the Lac operon
low glucose and high lactose
what can turn of the Lac operon
Lac repressor
what are not found in eukaryotes that prokaryotes use for regulation of gen express
operons
what’s the eukaryotic gene control region made of
promotor and cis-regulatory seqs
how are genes in eukaryotes enabled
binding of coactivator for transcription
how are genes in eukaryotes disabled
binding of co-repressor to stop transcription
what do chromatin remodeling complexes make
histone chaperones
what do histone chaperones do (2 things)
nucleosome removal/remodel
histone replacement
how do transcription activators promote transcription
releasing RNA polymerase from the promotor region
what do insulator elements do on eukaryotic DNA seqs
select domain of transcribed chromatin
how can transcription be inhibited in eukaryotic cells
- comp DNA binding
- masking of activation surface
- use of chromatin remodelling complexes
- histone deacetylase
- histone methyl transferase
can how nucleus be destroyed
using UV light
what is the isoelectric point of a gene
pH where molecule has no charge
what are 6 steps where gene expression can be controlled
- transcriptional control
- RNA processing control
- RNA transport control
- mRNA degradation control
- translation control
- protein activity control
what are cis-regulatory seqs
where transcriptional regulators bind to
how much of protein coding genes are transcriptional regulators
10%
what are transcriptional regulators structural motifs
how the interaction between 2 helices affect the target repress gene
what must a TF to turn on gene expression
dimserisation
what are the contact points that transcriptional regulators share w DNA
ionic bonding
hydrogen bonding
hydrophobic interaction
