Question

The map of the lac operon is:    POZY  

The promoter (P) region is the start site of transcription through the binding of RNA polymerase before actual mRNA production. Mutationally altered promoters (P^-) cannot bind RNA polymerase. Certain predictions can be made about the effect of P^- mutations. Use your predictions and your knowledge of the lactose system to complete the following table. Insert a “+” where an enzyme is produced and a “-“ where no enzyme is produced. The first one has been done as an example.

Beta-galactosidase		Permease
	No lactose	Lactose	No lactose	Lactose
I+P+O+Z+Y+/I+P+O+Z+Y+	-	+	-	+
I+P+O+Z-Y+/I+P-OCZ+Y+
I+P+O+Z+Y+/I+P+OCZ+Y-
I-P-O+Z+Y+/I-P+OCZ-Y+
I+P+O+Z+Y+/I+P+O+Z+Y+
I-P+OCZ+Y-/I+P+O+Z-Y+
I-P-O+Z+Y+/I+P+O+Z-Y+
ISP+O+Z+Y-/I+P+O+Z-Y+
I+P+O+Z+Y-/I+P+O+Z+Y-

Answer 1

                                             No lactose Lactose No Lactose      Lactose        

I⁺P⁺O⁺Z^-Y⁺/I⁺P^-O^CZ⁺Y⁺                  -                      +                     -                     +

I⁺P⁺O⁺Z⁺Y⁺/I⁺P⁺O^CZ⁺Y^-                 -                      +                     +                    -

I^-P^-O⁺Z⁺Y⁺/I^-P⁺O^CZ^-Y⁺                   +                     + -    -

I⁺P⁺O⁺Z⁺Y⁺/I⁺P⁺O⁺Z⁺Y⁺                -                      +                     -                      +

I^-P⁺O^CZ⁺Y^-/I⁺P⁺O⁺Z^-Y⁺             +                      +                    -                      -

I^-P^-O⁺Z⁺Y⁺/I⁺P⁺O⁺Z^-Y⁺                  +                     +                    -                       -

I^SP⁺O⁺Z⁺Y^-/I⁺P⁺O⁺Z^-Y+            -    -     -    +

I⁺P⁺O⁺Z⁺Y^-/I⁺P⁺O⁺Z⁺Y^-            -                      +                     +                     +