ne102 3/16 lecture - regulation of gene expression + gurdon's experiment

ways to control protein amounts in a cell? why is ts important?

transcription to mRNA + protein degradation; important to define cellular function + development

what do specialized cells have in common?

same DNA

what makes specialized cells different?

DNA may not be accessed in the same way (ex: certain genes that encode for specific proteins are different for each cell)

regulation of gene expression

controlling overall amounts of protein + RNA by degradation pathways → inc/dec transcription and translation of selected genes

how RNA poly can latch onto DNA?

TBP (TFIID attached) binds to TATA box → TFIIB stabilizes complex → TFIIE, RNA poly II, + TFIIH bind → TFIIH phosphoylates the tail + RNA poly detaches from TFs

when can TFIID bind to TATA box?

general TFs interact with DNA ONLY when transcription has to start

whhat controls accessibility/non-accessibility of specific genes, controlling a cell’s shape/function?

transcription regulators

what are TRs?

proteins that make region of DNA within a gene of interest accessible for transcription → formation of the mediator complex of general TFs with TATA box

transcription initiation process

TR composed of eukaryotic activator protein + enhancer site → favor transcription, change conformation of chromatin → binding of general TFs, mediator, + RNA poly

how to regulate chromatin shape + accessibility to TATA box?

specific proteins of the mediator will selectively interact either with HATs/HDACs → once TRs bind to DNA element + mediator forms → chromatin shape + TATA access

what did gurdon do?

frog generated in absence of egg/sperm fertilization

gurdon’s hypothesis

the DNA is the same in all cells, but the proteins expressed might be different in each cell type

gurdon’s experiment

unfertilized egg → nucleus destroyed by UV light → nucleus from skin cells injected into egg (contains 2 sets of chromosomes) → normal embryo/blastula → tadpole

gurdon’s findings

oocytes were not replaced w diff cell types → TRs are proteins, therefore translated in the cytosol + move to nucleus to control selective gene expression (magic is in cytosol!)

transcription regulators facts

1. different from general TFs

2. specialized proteins that regulate transcription of specific genes/proteins

3. can be cell specific to regulate expression of other proteins needed for development/function of specific cell type

4. important during development, where undiff stem cells differentiate into specific cell types