BIOLOGY 151 Lecture Notes - Lecture 22: Lac Operon, Adenine, Escherichia Coli
Document Summary
Glucose is preferred sugar for e. coli because it is the first substrate in glycolysis, in which atp will be produced as an energy source to carry out basic cellular functions. Any other sugar e. coli obtains, it must turn the sugar into glucose for energy by glycolysis. If there is not a lot of glucose but there is a lot of lactose around, then e. coli needs to express enzymes to turn lactose into glucose. Lac operon: promoter + several genes = operon. Only one mrna will be produced, however there will be more than one protein coding region. Lac z codes for b-galactosidase (aka b-gal) Enzyme x will turn galactose into glucose enzyme x is not regulated by lac operon. Membranes are semi-permeable and sugars cannot diffuse through it. Therefore in order for lactose to cross through the membrane, it must have a channel: permease is located in the membrane, and is a channel that.
