If 10 protons are pumped out per NADH and 4 must flow in to produce 1 ATP, the proton-based P/O ratio is 2.5 for NADH as the electron donor and 1.5 (6/4) for succinate.

TLS Online TPP Program

#Id: 6371

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6372

#Unit 2. Cellular Organization

lacZ encodes for b-galactosidase,a tetramer of 500 kD. The enzyme breaks lactose is cleaved into glucose and galactose.  This enzyme also produces an important byproduct, b-1,6-allolactase.

TLS Online TPP Program

#Id: 6373

#Unit 2. Cellular Organization

The lac mRNA (as most mRNA is in bacteria) is extremely unstable and decays with a half-life of only 3 minutes.

TLS Online TPP Program

#Id: 6374

#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

TLS Online TPP Program

#Id: 6375

#Unit 2. Cellular Organization

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

TLS Online TPP Program

#Id: 6376

#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.