week 6 Flashcards
what cause steh transition from transcription to translation?
RNA binding to teh Shine Dalgarno sequence
what does the inducer do?
it turns on gene expression
how do activator and repressor proteins know when to do their jobs?
small effector molecules
the sigma factor is unique to what cellular org?
bacteria
what are the genes called that are constantly in demand and are always being made?
constitutive genes
3 ways in which bacteria regulates during the whole central dogma process
- transcriptional reg.
- translational reg: how much protein is made
- posttranslational reg: protein activity either increased/decreased thru cleavage or phosphorylation
specific ways that in transcription, bacteria regulates
i: activator/repressor binds to promoter
e: attenuation (a premature stop)
t: hairpin loop
riboswitches
- in bacteria and archaea
- when on (2 looking stem loops), transcription is off
RNA thermometers
- same as riboswitch except in translation
eukaryotic central dogma (gene expression)
- moves from nucleus to cytoplasm
- monocistronic bc linear chromosome
- 3 RNAP
- complex TF2D requires the TATA box
- mRNA modifications: poly a tail and splicing
archaeal central dogma (gene expression)
- mixture of euk and bacterial properties
- bac: polycistronic, 1 RNAP, no splicing
- euk: TATA box, histones, accessory factors
operons
- multiple genes, 1 promoter
- “all in this together”
- mono in euk
- poly in a and b
lac operon is induced by?
lactose
- lactose present, then the allolactose will bind to the repressor and gene expression is on
——– the binding of allolactose makes it impossible for the lac repressor to bind to the operator site
- neg control bc on is the “default kind of” (aka inducible control)
—–it is on in the presence of lactose
trp operon is repressed by?
tryptophan
- when trypto. is present, it is a co-repressor and turns off gene expression
- the operon codes for 5 genes that synthesize trypto.
- feedback loop
what is considered small effector molecules?
inducers and repressors
in diauxic growth, is glucose or lactose used first?
glucose
- when theres no/low glucose, then it uses lactose
- so lac operon is active when theres lactose (obv) and no/low glucose
in catabolite repression, glucose is present, so what does that mean for the lac operon?
how are we able to go from using glucose to lactose?
adenylate cyclase converts ATP to cAMP which activates CAP/CRP and ,makes the lac operon active
lac Z makes what protein?
B-galactosidase
lac Y makes what protein?
lactos epermease
lac A makes what protein?
B-galactoside- transacetylase
when there’s no glucose and only lactose, whats happening to the lac operon?
transcription
- allolactose bind so lac repressor is inactive
when there’s both glucose and lactose, whats happening to the lac operon?
no transcription
- lactose present -> allolactose will bind -> inactive lac repressor
- but bc glucose is present -> adenylate cyclase will be inactive -> no CAMP -> no CAP
when there’s only glucose, whats happening to the lac operon?
no transcription
- bc no lactose -> lac repressor binds
what do alternative sigma factors do?
they immediately change the expression of genes bc they direct the RNAP to specific bacterial promoters
the 2 examples of second messengers
-amino acid starvation (stringent response)
- c di-GMP
whats happens in amino acid starvation?
- stops producing tRNA and rRNA so can focus on increasing aa production
- an uncharged tRNA comes to teh A site of a ribosome -> activates RelA -> produces pppGpp
how do cyclic dinuceotides (cdiGMP/cGMP, cdiAMP) help teh cell?
- movement
- cell cycle progression
- biofilm formation
- virulence
global regulatory systems use many type so of regulation such as…
- 2 component signal transduction system
- sigma factors
- second messengers
what is the 2 component signal transduction system?
- has a sensor kinase : which is just a protein thats in the plasma membrane that is so big that it’s sticking out to the outside and inside environment
—– it phosphorylates itself and gives that to a response regulator which will cause it to have conformational change and cause transcriptional changes
what is chemotaxis and what is it an example of?
- it’s an ex for 2 system signal transduction
- sensor kinase= CheA
- response regulators = CheY and CheB
quorum sensing
- AHL binds to LuxR -> transcription on (for everything AHL related)
archaeas have a blank -like RNAP in a blank-like environment.
eukaryotic
bacteria
