Transcriptional Regulation & NF-kB Viral Hijacking

cytokines

small secreted proteins that circulate through body and activate immune cells

cytokine storm

dysregulation leads to sustained elevation well above normal activated cytokine levels, leads to elevated blood clotting, multiple organ failure, death

operon

set of genes with related functions that are regulated together by one piece of mRNA encoding the related proteins

polycistronic mRNA

mRNA conding for more than 1 polypeptide, found only in prokaryotes

structural and regulatory genes

operon consists of these two things

structural genes

code for the enzymes/proteins of interest

regulatory genes

control the expression of structural genes by expressing regulatory proteins

operator

sequence located between core promoter and first structural gene, where proteins bind to to promote/inhibit transcrtiption

lac operon

example of a repressor/use of negative control of transcription

repressor

binds to operator to inhibit operon, uses negative control of transcription because when it binds it turns transcription off since polymerase is unable to bind to promoter

allosteric regulation

causes chemical/physical change that prevents binding

operon de-repression, negative control

lac regulation is an example of

substrate induction

substrate induces its enzyme

constitutively expressed

always expressed/on

Glucose pathways are constitutively expressed. If glucose is present, the cell turns down other pathways (such as lactose catabolism) to conserve energy. Conversely, if glucose is absent, the cell activates pathways for available substrates like lactose

describe positive control mechanism of the lac operon

trp operon, end product repression

binds to operator in presence of tryptophan, ex of __ __ ____

end product repression

prevents initiation of transcription

cis-acting elements

regions in/around promoter to which regulatory proteins may bind

trans-acting elements

regulatory genes, exist far away on DNA (ex gene for repressor)

transcription factors, DNA sequences

trans-acting proteins (_) bind to cis-acting elements (_)

proximal control elements

<100 bp up/downstream

distal control elements

>100bp up/downstream (ex enhancers, repressors)

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