exam 3 part 2 Flashcards
structural genes
encode proteins used in metabolism or play a structural role in the cell
regulatory genes
encode products that interact with other sequences and affect transcription/translation of these sequences
regulatory elements
DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences
rapid turn on/ off
ability to respond to sudden changes
sequential gene expression
cascades of gene expression that turn on in order
constitutive
always on
positive control
regulatory protein (activator) binds to DNA to stimulate transcription
negative control
regulatory protein (repressor) binds to DNA to prevent transcritpion
inducible control
transcription is normally off and is turned on when a small molecule binds the regulatory protein
repressible control
transcription is normally on and is turned off when a small molecule binds the regulatory protein
operon
segment of DNA containing controlling regions and structural genes controlled by those regions
regulatory gene
codes for repressor
promotor
binds to RNA polymerase to allow transcription
operator
interacts with repressor
lacZ,Y,A
transcribed and translated into proteins
lac Z
B-galactosidase
lac Y
permease
lac A
transacetylase
polycistronic mRNA
produced during transcription
cis acting
action of an element affects only the genes adjacent to it
- operator and promoter elements
trans acting
diffusible product is produced. mutant doesn’t have to be adjacent
- repressor
I+
normal repressor
I-
repressor cannot bind to operator
Is
stays stuck to operator meaning repressor cannot bind allolactose
Oc
operator cannot bind to repressor
P-
promoter cannot bind to RNA polymerase
lacI-
constitutive always on
lac Oc
constitutive always on
I+ is —- to I-
transdominant
negative control
regulatory molecule binds to the DNA to turn genes OFF
repressible system
repressor must interact with corepressor so the complex can bind to the DNA and turn the off the operon
allosteric action
a change occurs in the conformation of the repressor when it binds to Trp
feedback inhibition
excess trp in cell decreases the production of the enzymes used to make trp
attenuator
located in the leader sequence and responsible for decreasing transcription when trp is present
antisense RNA
small RNA molecules complementary to parts of the mRNA
- base pair to mRNA and inhibit translation
riboswitches
RNA sequences in the mRNA that affect the translation of that mRNA
