ch 8 Flashcards
transcription starts at
promoter!!!!! BOTH
pro transcription occurs at
nucleiod/cytoplasm
transcription and translation is
coupled
promoter
sequence that recruits RNA pol for gene expression, contains -10 an d-35 sequences
-35 and -10 sequence
part of e coli promoter, consensus sequence
transcription start site number
+1
-10 sequence
Tata box or pribnow box
core enzyme
5 polypeptide chain, look like crab claw, catalyze polymerization
sigma factor
directs poly to promoter, helps with specific initiation of transcription
holoenzyme
core and sigma subunit, sigma can vary from each holoenzyme
different sigma subunits leads to
controlled transcription, will bind to different shit
sigma factor 70
important to life, housekeeping genes
key functions of sigma factor
- target RNA polymerase to holoenzyme and to specific promoters
- melt -10 region of promoter and stabilize it as ssDNA
- interact with other transcription factors
transcription steps
- initiation
- elongation
- termination
initiation steps
- promoter recognized and binded to
- close promoter complex formed
3.open promoter complex formed - abortive transcription
- promoter escape- sigma displaced?
close promoter complex formed
open up at -10, then starts-ish
elongation and sigma subunit relationship
no sigma required
transcription bubble
area of denatured DNA where rna synthesis is occurring- 20 nucleotides long
proofreading
rna poly has it but its not like ours
termination types
rho indie and rho dependent
rho indie relies on
inverted repeats to have hairpins, usually close to poly adenine (au) sequence
rho dependent
binds to rut, rho chases rna polymerase, no au sequence
constitutive genes
always on, housekeeping genes
repressible genes
on unless off
inducible genes
off unless on
operons!! mostly in prokaryotes
groups of genes with related functions
operons have
promoter, operator, regulatory genes, make polycistronic (multiple genes in one mRNA) mRNA,
operons allow for
fast environment change
cis acting sequence
regulatory element
trans acting factors
binds to cis to activating or deactivate
lac operon
induced yasssss
trp
repressed
lac operator binds to
lac repressor protein
CAP
catabolite activator protein site, binds to protein called CAP (when glucose levels are low)
lac pi
promoter, allows lac I gene to constitutively (always) express
lac I gene
repressor binds to operator unless lactose is available
cAMP
binds to CAP when gluc low to allow for gene to express
glucose only
lac repressor binds to operator, no CAP binding to site
lactose and glucose
repressor comes off, cap no bind (basal level)
lactose only
high transcription, 5000 molecules of shit in 8 minutes
others modes of regulation (lac)
glucose inhibits transport of lactose
regulation by RHO (when not enough amino acids)
beta glacatosidase breaks down what
lactose into lactose and glucose
beta glacatosidase can modify lactose into
allolatose, binds to repressor protein to deactivate lac
IPTG
can bind to repressor and allow for transcription
doesn’t get broken
cooperative binding example
when cap is bound and glucose levels are low
RNA poly recruited
allosteric mods example (lac)
when lac repressor binds to allolactase
cap and cAMP
DNA looping
allows multiple proteins to interact with RNAP
what type pr protein is lac repressor
dimeric
allosteric mods of lac operon
alloactose and IPTG
DNA looping
attenuation
gene relation in transcribed dRNA
ex trp
when trp low
ribosome pauses, stem loop (anti terminator) forms in mRNA
when trp high
terminator loop form, no more transcription
riboswitches
Specialized domains within certain mRNA that act as switchable on/off elements- no protein required
aptamer will
binds to target metabolite
expression platform
changes to RNA folding due to metabolite binding events
common in bacteria
expression platform allows for
temp sensing, salt metal ion recognition, amino acid recognition and other small organic metabolites
glucosamine-6- phosphate is controlled by
riboswitch ribozyme
regulon
collection of regulated genes
autoinducers
shit turn on to send signal to other bacteria near by
to form biofilm
quorum sensing
enough bacteria to change what going on in biofilm
elongation steps prokaryotic
Transcription bubble, RNA pol reads template, Proofreading
cooperative binding
when two or more ligand molecules can bind to a receptor molecule.