lac operon Flashcards
what are structural genes and sequences for transcriptions known as
operons
what gene on an operon has its own promoter
what does this bind to
repressor
binds to an operator
what is the “switch” that turns genes on and off on an operon
operator
what is the type of operon:
always on
always off but can be turned on
always on but can be turned on
constitutive
inducible
repressible
how do you know an operon is inducible
if it is expressed in the presence of an agonist
what is the metaphor for
positive control
negative control
needing the right key or the car won’t stat
is expressed when the regulatory molecule mutated
inductor binds to repressor and translation occurs
negative inducible
inductor ends to activator and translation occurs
positive inducible
translation occurs till corepressor binds to repressor
negative repressible
translation occurs till corepressor binds to an activator
positive repressible
negative binds to _____
positive binds to ______
repressor
activator
for lactose metabolism, what type of ezyme is present
what is the inducer
inducible
lactose
is the regulatory portion up or downstream in lactose metabolism
upstream
what is a gene when many open reading frames encode multiple proteins
polycistronic
proteins go Z,Y,A on the lac operon, what enzymes do these encode for in order
B galactidase
lactose permase
galactoside
cis acting molecule on operon
trans acting molecule on operon
regulatory proteins on the same DNA as the gene
repressors or activators that bind to regulatory proteins
why does the lac I gene marker code for
repressor
what does the repressor bind to on the lac operon and WHY
in the presence of lactose
without the presence of lactose
allolactose so that the operon can start the transcription of enzymes to break it up
the operator and halts transcription of enzymes bc theres none even present
what does RNA polymerase bind to
the promoter
what happens to the operon if lac I is mutated
no restriction enzyme is made and even in the absence of lactose, enzymes are always made (I-)
what happens to the lac open if I is super mutated (Is)
makes a huge repressor and even in the presence of lactose, no enzymes are made
what happens in lac operon if the operator is mutated
the repressor is made but it cant bind to the operation
even in the absence of lactose, enzymes are still made
what happens when there is a mutation in one of the genes
defective genes are made
what is special about a heterozygote who only has one lac I gene mutated
repressors from the other allele can still bind to operators
