00:01
This question asks, what is catabolite repression? how does it allow a bacterial cell to use glucose in preference to other sugars? so in catabolite repression, we see that the presence of glucose inhibits or represses the transcription of genes involved in the metabolism of other sugars.
00:51
So what does this mean in actuality? well, we could take a look at the lac -opron as an example of catabolite repression.
01:01
So in the lack -opron, we are going to have, of course, our operon with the structural genes that include for proteins that degrade lactose, turning it into a favorable form, a favorable saccharide for energy production in these bacterial cells.
01:21
And of course we are going to have our operator region, the promoter region, but it's important to note that there is going to be a repressive protein that is going to bind to the operator, preventing transcription from occurring by inhibiting the assembly of the rna polymerase machinery, and in doing so, we are not going to see transcription of the genes necessary for lactose degradation.
01:48
So you might think, well, isn't that a bad thing? don't we want these genes to be expressed? well, if lactose is present, then the answer is yes...