The light-absorbing/ emitting center of GFP (its chromophore) comprises an oxidized form of the tripeptide –Ser65–Tyr66–Gly67

TLS Online TPP Program

#Id: 563

#Unit 2. Cellular Organization

B-1,6-allolactase is a true inducer of Lac operon which activates Lac ZYA gene expression by inhibiting Lac Repressor

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#Id: 564

#Unit 2. Cellular Organization

Negative Regulation/ Positive Regulation or catabolic repression

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#Id: 565

#Unit 2. Cellular Organization

Molecules that induce enzyme synthesis but are not metabolized are called gratuitous inducers such as IPTG

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#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.

       

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#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.