1. For the following partial diploid E. coli strains, indicate in the table whet
ID: 66535 • Letter: 1
Question
1. For the following partial diploid E. coli strains, indicate in the table whether ß-galactosidase and permease will be made under the noted conditions. Use “+” to indicate enzymes that are produced and “-“ to indicate that no enzyme is produced. You can assume that glucose is absent at all times. 3 pts
ß-galactosidase Permease
Partial Diploid No lactose Plus lactose No lactose Plus Lactose
a.
I+O+Z+Y+/
I+O+Z+Y+
b.
I-OcZ+Y-/
I+O+Z-Y-
c.
I-O+Z+Y+/
I-O+Z-Y+
a.
I+O+Z+Y+/
I+O+Z+Y+
b.
I-OcZ+Y-/
I+O+Z-Y-
c.
I-O+Z+Y+/
I-O+Z-Y+
Explanation / Answer
ß-galactosidase Permease
Partial Diploid No lactose Plus lactose No lactose Plus Lactose
a.
I+O+Z+Y+/
I+O+Z+Y+
-
+
-
+
b.
I-OcZ+Y-/
I+O+Z-Y-
+
+
-
-
c.
I-O+Z+Y+/
I-O+Z-Y+
+
+
+
+
In lac operon, expression of lac operon genes is dependent on the presence of lactose in the medium. I codes for a repressor protein which binds to operator in absence of lactose and hence further genes are not expressed. But in presence of lactose, inducer binds to repressor protein and let the operator to transcribe the genes. In lactose operon, allolactose acts as an inducer.
In case (a), all genes are +, hence in when lac operon will be regulated normally as said above.
In case (b), diploid has I- and I+, this will lead to form repressor protein. But Operator is constitutively expressed. Hence, there will be a continuous expression of lac operon genes irrespective of the presence of lactose in the medium. Both Permease genes are - , so it will not be expressed.
In case (c), I is - so there is no production of the repressor protein. That's why operator will allow continuous expression of lac operon genes.
a.
I+O+Z+Y+/
I+O+Z+Y+
-
+
-
+
b.
I-OcZ+Y-/
I+O+Z-Y-
+
+
-
-
c.
I-O+Z+Y+/
I-O+Z-Y+
+
+
+
+
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.