Racemase is responsible for converting D amino acid into L form.

TLS Online TPP Program

#Id: 566

#Unit 2. Cellular Organization

IPTG (isopropyl b-D-1-thiogalactopyranoside) X-gal (5-bromo4-chloro-3-indolyl-b-D-galactopyranoside). When acted on by that enzyme, X-gal releases a blue color that makes it useful as substrate in assays.

       

TLS Online TPP Program

#Id: 567

#Unit 2. Cellular Organization

The lac operon has three paradoxes

1-If the operon is in a repressed state, how does the inducer enter the cell to start the process of induction

2- If the operon is in a repressed state, how Repressor is removed with allolactose 

3- How is allolactose synthesized in Repressed state Answer is Leaky Expression

TLS Online TPP Program

#Id: 568

#Unit 2. Cellular Organization

Leaky Expression

In repressed state, an occasional transcript gets made. This happens because every so often, RNA polymerase will manage to bind the promoter in place of the Lac repressor. This leakiness encode meager level of Z, Y and A.

TLS Online TPP Program

#Id: 569

#Unit 2. Cellular Organization

Leaky Expression cannot happen in P- and Z- mutants

TLS Online TPP Program

#Id: 570

#Unit 2. Cellular Organization

The lac operator is 21-bp sequence with twofold symmetric and is recognized by two subunits of Lac repressor

 

TLS Online TPP Program

#Id: 571

#Unit 2. Cellular Organization

Constitutive mutations occur at 8 positions in the operator between +5 and +17 called OC