2E Flashcards
Regulatory genes
regulatory genes encode for a repressor protein that can block transcription when it binds to the operator region
structural genes
encode for enzyme that are used to create the amino acid trypotphan in a biochemical pathwya
What happens if a repressor gene is present
if a repressor gene is present, the repressor gene binds to the operator region which prevents RNA polymeraase from copying the gene into mRNA.
trp operon
contains a series of genes involved in the production of the amino acid tryptophan
What happens if tryptophan is high
repression occurs totranscription of the trp operon structural gene is stopped, therefore energy is saved by preventing unnecessary production of tryptophan.
What happens if tryptophan is low
transcription of trp structural genes is inititated
There are 4 regions in the tro opern diagram, of these 4 which are complemenatry
region 1 and 2 have complementary base sequences
and region 3 and 4 have complemetnary base sequences
when does repression occur
when tryptophan is high
repression
a mechanism used to decrease or inhibit the expression of a gene
Process of repression when there is TOO MUCH TRYPTOPHAN:
also known as REPRESSION OF TRP OPERON
- lots of tryptophan
- regulatory gene is transcribed into mRNA
- mRNA is translated into a protein called a repressor structure
- repressor protein is complementary to the tryptophan
- tryptophan and repressor form a complex, therefore repressor becomesactive
- active site binds to the operator region
- RNA polymerase unable to bind, therefore saves energy
- transcription cannot occur because trp structural genes product have stopped.,therefore production of tryptophan cannotoccur
Process that occurs to produce tryptophan when there to too low tryptophan:
- Not enough tryptophan in the cell
- Repressor cannot form a complex with the tryptophan
3, Therefore, inactive repressor is unable to bnd to the operator region
- Rna polymerase runs along the messenger RNA to make enzymes that produce tryptophan
What 2 processes occur at the same time
Transcription and translation happen at the same time
Attenuation
the second process of trp regulation, which acts in response to the amount of tRNA bound tryptophan
repression of trp operon
The regulatory gene is constantly expressed, producing a repressor protein
if tryptophan is high, it binds to the repressor protein allowing for a conformational change to occur, ultimately causing the repressor to become active.
The active repressor binds to the operator region of the gene which prevents the transcriciption of the structural gene, trp operon.
How is the repressor gene affected if tryptophan is high/how does the repressor become active
if tryptophan is high, it binds to the repressor protein allowing for a conformational change to occur, ultimately causing the repressor to become active.
