The Order of the Structural Genes in the Lac Operon

Question

The order of the structural genes in the lac operon is
A)5'-lacY-lacZ-lacA-3'.
B)3'-lacZ-lacY-lacA-5'.
C)5'-lacZ-lacY-lacA-3'.
D)3'-lacY-lacA-lacZ-5'.
E)5'-lacA-lacY-lacZ-3'.

Accepted Answer

The orientation of genes in the lac operon is important for the correct reading of the genetic information. The lac operon contains three structural genes, lacZ, lacY, and lacA, which are involved in the metabolism of lactose. The promoter sequence is located upstream of these genes, and the entire operon is transcribed as a single mRNA molecule. The orientation of the structural genes in the lac operon is important because it determines the order in which the enzymes are produced. The correct order of the genes in the lac operon is 5'-lacZ-lacY-lacA-3', which corresponds to choice C.