Flashcards in L20-22: Gene Regulation Deck (17)
define gene regulation
the rules and mechanisms controlling the expression of genes
two types of genes
constitutive: always expressed + essential
contingency: encode products that confer advantage under special condition
difference in gene regulation of prokaryotes and eukaryotes
1. purpose (p=growth, differentiation)
2. challenges (p= continual changes, constant enviro)
3. range (p= total switch off rare, common)
4. production of mrna
4 ways cell can control protein production
1. transcriptional control (when gene is transpired )
2. rna processing control *how rna is spliced)
3. translational control (which mrnas are translated)
4. ppost- translational control (on/off after protein made)
repressor protein= prevents transcitopion
activator allows transcriptions
genes adjacent - transcribed from single promotor into mRNA
operon for aa trptophan production
DNA sequenceRNA polymerase binds to, open the DNA double helix, begin synthesising the mRNA.
A short region of DNA to which the repressor protein binds; it controls the expression of the genes adjacent to it in the operon.
rotein that binds to an operator sequence to prevent transcription of the adjacent genes in the operon.
define polycistronic mrna
RNA that has more than one coding region and is translated into a number of different proteins; formed when an operon is transcribed.
difference of lac and trp operon
what proteins carry out lactose metabolism
- galactosidase and lactose permease
how does negative control of lac work
repressor protein binding to the operator and preventing RNA polymerase
from binding to the promoter : no transcription
when lactose is present, its derivative allolactose acts as an inducer by binding to the repressor causing it to dissociate from the operator : transcription of the structural genes occurs
is lac positive or negative control