You grow cells of this bacterium in a variety of different media. Under which conditions would you expect the galA or the argB or neither to be expressed?
Minimal medium with glucose as the only sugar
Minimal medium with galactose as the only sugar
Minimal medium with glucose as the only sugar and arginine
Minimal medium with galactose as the only sugar and arginine

Question

You grow cells of this bacterium in a variety of different media. Under which conditions would you expect the galA or the argB or neither to be expressed?
Minimal medium with glucose as the only sugar
Minimal medium with galactose as the only sugar
Minimal medium with glucose as the only sugar and arginine
Minimal medium with galactose as the only sugar and arginine

anonymous · Answer

here is the first part of the question: Consider the following genes in a hypothetical bacterium:
galA – encodes an enzyme that is required for cells to digest the sugar galactose
argB – encodes an enzyme that is required for cells to produce the amino acid arginine

thomaster · Answer

galA will be expressed when galactose is in the medium.
galA will not be expressed when glucose is in the medium.

i'm a bit confused about the argB part... it encodes an enzymes that is required for the cells to produce arginine.. So the medium does not have to contain arginine. I also have no idea when argB will be expressed.