Sets 15 Flashcards
what determines how much mRNA is made ?
the promoter and surrounding sequences
what is an operon
multiple genes being transcribed together and producing separate proteins
how many promoters are in an operon
1
how many start and stop codons
1 for each gene inside the operon
what is catabolism
” cats break things” breaking down larger molecules into smaller molecules to get energy
what is anabolism ?
bringing small molecules into larger molecules using energy
what does permease do ?
allow lactose into the cell
can lac permase and B galactosidae be made without lactose
yes they can still be made but reduced level
when B- galactosidase catalyzes lactose what are the 2 thing it can become
- galactose & glucose
- allolactose
what are the 5 key things within the lac operon ?
- lacI
- Promoter
- lac Z
4.lac Y
5.lac A
what does the lacI gene make ?
a repressor of the lac operon
what does the lac Z gene make ?
B-galactosidae
what does the lac Y gene make
permase
what does allolactose do?
it is an inducer and binds to the repressor to stop it and allow transcription
what gene is always transcribed & translation in the lac operon
lacI
where does the repressor protein bind to ,to stop transcription
it binds to the operator
can lactose still enter the cell even though the operon is repressed ?
yes it can still enter
what does lac A make ?
transacetylase
what is constitutive expression
its being made all the time
what are the 2 key components of the lac repressor
- DNA binding domain
- inducer binding domains
how many operators are there ?
there are 3 operators
what does I- mean ?
there no repressor as the lacI gene is not working and the lac operon is expressed ( translated)
what does Oc mean ?
a mutant operator where the repressor cannot bind at all ; transcription will go on
what is cis action
mutation on the gene only affecting that one gene (itsef)
what is trans action ?
elements that can affect other genes
what is cis and what is trans on the lac operon?
operators and promoters are cis bc it on genes there are sites
protein made from lac genes are trans bc they can attach to other gene ex . inducer made from one gene can travel to another gene and induce their own made repressor.
what is I”s”?
its super repressor; completely shuts down the lac operon as inducer cannot bind to it at all
