The hyperpolarization of rod cells:

  Reduces the release of glutamate

  Generates a signal in the bipolar cells

  Leads to AP in ganglion cells 

TLS Online TPP Program

#Id: 606

#Unit 2. Cellular Organization

N binds to RNA transcribed from DNA containing a nut sequence. Thus, once RNA polymerase has passed a nut site, N binds to the RNA and from there is loaded on to the polymerase itself. In this state, the polymerase is resistant to the terminators found just beyond the N and cro genes. 

TLS Online TPP Program

#Id: 607

#Unit 2. Cellular Organization

The E. coli trp operon contains the 5 genes Trp-EDCBA for the anabolic enzymes to make the tryptophan.

TLS Online TPP Program

#Id: 608

#Unit 2. Cellular Organization

Major enzyme is Tryptophan Synthase

TLS Online TPP Program

#Id: 609

#Unit 2. Cellular Organization

Major enzyme is Tryptophan Synthase whose activity is reduced when trp concentration is high.

 

TLS Online TPP Program

#Id: 610

#Unit 2. Cellular Organization

Trp operon is negatively regulated by two ways

1. Repression

2. Attenuation

Why is this extra control of two layers on trp operon needed? 

TLS Online TPP Program

#Id: 611

#Unit 2. Cellular Organization

The answer probably lies in the fact that repression of the trp operon is weak—much weaker.