Would u expect E.coli Lac to grow on a medium in which lactose is the onl carbon source? Why?

Question

Would u expect E.coli Lac to grow on a medium in which lactose is the onl carbon source? Why?

Answer 1

Look in your textbook. :P

Answer 2

I would say yes.  If I remember correctly, the presence of the lac operon in the genome means the E.coli should be able to metabolize lactose when the supply of glucose runs out.  The lack of glucose turns on the promoter and the cells can then use the lactose.

Answer 3

Yes, when E.coli are grown on a lactose medium, the genes that code for the production of lactose permease enzyme( allows bacteria to take up lactose), and beta galactosidase enzyme     ( hydrolyses lactose to glucose and galactose) are switched on and the E.coli produce both enzymes. Lactose is therefore an environmental factor that induced the genes to express themselves.

Answer 4

Generally we refer to the mutations the organisms carry when describing the organism and assume any unnamed genes are wild-type.  The E. coli lac mutant carries a mutation in the lactose utilization genes (lac operon) and would not be able to utilize lactose as a carbon source.  Thus, this mutant would not be able to grow on medium containing lactose as the sole carbon source.  The mutation sometimes is more specifically referred to as lac-.  The wild-type organism (lac+) would be able to grow on medium containing lactose as the sole carbon source.