BMS1062 Lecture Notes - Lecture 10: Corepressor, Transfer Rna, Allolactose
14 Aug 2018
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Know that cells do not express all genes all the time. Know how repressor and activator proteins differ in function. Know how the e. coli lac operon is regulated. Different genes are expressed in response to different environments. Eukaryotes ie: in the presence of different types of food substrate (lactose, lipids etc. ) To not waste energy expressing genes and producing proteins that are of no use in the particular environment. Note : the presence of activator and repressor proteins. Also note the tata box, a type of promoter sequence, which specifies to other molecules where transcription begins ( especially the sigma factor) Rna polymerase is usually all that is needed to start gene expression in prokaryotes, ie prokaryotic genes are by default on. In eukaryotes however, genes are off by default and need enhancer proteins and transcription factors to start transcription, this is because genes are always heavily condensed as chromatin, tightly wound around nucleosomes ( a protein complex)
