Question

Regulation in bacteria and phages includes a number of exotic terms with which you can amaze/alarm your friends. Twelve terms are given below followed by twelve statements. Write the letter of the correct term. A single letter is sufficient. Not all letters need to be used, and a particular letter may be used more than once. (15 points)

Term list:

1. temporal control

2. positive control

3. negative control

4. inducible

5. non-inducible

6. repressible

7. constitutive

8. operator

9. repressor

10. effector molecule

11. feedback inhibition

12. suppressor mutation

13. 1. Phenotype with respect to beta-galactosidase synthesis for the partial diploid I+ O+Z+/I- Oc Z-     

___________

2. Phenotype of I+O+Z-/I+Oc Z+

___________

3. Phenotype of I+O+Z-/I-OcZ-

___________

4. Phenotype with respect to synthesis of tryptophan enzymes in the trp operon trpR+ Oc S+ (trpR codes for the repress, S=structural genes).

_______

5. Phenotype of trpR+ O+ S+ in the presence of tryptophan.

________

6. Regulatory molecule must be present at site in DNA (such as promoter) so that transcription can occur ____________.

7. Small molecules that bind to regulatory molecule such as repressor__________

8. Mutation that reverses effect of another mutation at a different site.

____________

9. Type of operons responding to catabolite repression (glucose effect).

___________

10. Post-translational control of biosynthetic pathway.

___________

                    11. Regulatory molecule that binds to operator region in DNA.

Answer 1

1. Phenotype with respect to beta-galactosidase synthesis for the partial diploid I+ O+Z+/I- Oc Z-     

___________d. Inducible

(Because even one of the operator gene (O) is non functional (Oc) the other one (O+) is functional, hence lac operon here is inducible) ( Also atleast one copy of all the genes' -l O and Z functional forms (l+ O+ and Z+) are present. So lac operon will be functional.

1. Phenotype of I+O+Z-/I+Oc Z+

___________d. Inducible

(Because even one of the lac Z gene (Z) which synthesizes beta galactosidase is non functional (Z-) the other one (Z+) is functional, hence lac operon here is inducible)

1. Phenotype of I+O+Z-/I-OcZ-

___________e.non inducible

(Because both lac Z genes are non- functional (Z-), hence lac operon here is non inducible)

1. Phenotype with respect to synthesis of tryptophan enzymes in the trp operon trpR+ Oc S+ (trpR codes for the repress, S=structural genes).

_______g. Constitutive

Since operator region O is non functional (Oc) trp repressor cannot bind to the region to repress tryptophan synthesis. Hence the operon will be constitutive (ON all the time) in the presence and absence of tryptophan)

1. Phenotype of trpR+ O+ S+ in the presence of tryptophan.

________f.repressible ( since all the genes (trpR+ O+ S+ ) are of wild type ( functional), trp operon will be able to repress tryptophan synthesis.

1. Regulatory molecule must be present at site in DNA (such as promoter) so that transcription can occur ____________.h.operator

2. Small molecules that bind to regulatory molecule such as repressor__________ j.effector molecule

3. Mutation that reverses effect of another mutation at a different site.

____________i. suppressor mutation

1. Type of operons responding to catabolite repression (glucose effect).

___________d. Inducible

1. Post-translational control of biosynthetic pathway.

___________k.feedback inhibition

                    11. Regulatory molecule that binds to operator region in DNA - i.repressor