Rhizofiltration is a process that filters water through a mass of roots to remove toxic substances or excess nutrients. The pollutants remain absorbed in or adsorbed on to the roots. As the roots become saturated with contaminants, they are harvested and disposed. 

TLS Online TPP Program

#Id: 4052

#Unit 2. Cellular Organization

Each is produced by the successive replications of a synapsed diploid pair of chromosomes. The replicas do not separate, but instead remain attached to each other in their extended state, a process known as endoreduplication.

At the start of the process, each synapsed pair has a DNA content of 2C (where C represents the DNA content of the individual chromosome). This amount then doubles up to nine times, at its maximum giving a content of 1024C. The number of doublings is different in the various tissues of the D. melanogaster larva.

TLS Online TPP Program

#Id: 6359

#Unit 2. Cellular Organization

Operon consist

Physiology/Mechanism

Molecular biology/Biochemistry of component

Effect of mutations

TLS Online TPP Program

#Id: 6360

#Unit 2. Cellular Organization

Repressors impede access of RNA polymerase to the promoter and Activators enhance the RNA polymerase–promoter interaction.

TLS Online TPP Program

#Id: 6361

#Unit 2. Cellular Organization

Repressors bind to specific sites on the DNA. In bacterial cells, such binding sites, called operators

Regulation by means of a repressor protein that blocks transcription is referred to as negative regulation. Activators provide a molecular counterpoint to repressors; they bind to DNA and enhance the activity of RNA polymerase at a promoter; this is positive regulation.Repressor binding to DNA is regulated by a molecular signal called effector

TLS Online TPP Program

#Id: 6362

#Unit 2. Cellular Organization

Activators that stimulate this kind of promoter work by triggering a conformational change in either RNA polymerase or DNA; that is, they interact with the stable closed complex and induce a conformational change that causes transition to the open complex. This mechanism is an example of allostery.

TLS Online TPP Program

#Id: 6363

#Unit 2. Cellular Organization

There are 4 genes (I, Z, Y, A), 2 Promoters and 3 lac operators in Lac operon

The major O1 lac operator lies adjacent to promoter

The O1 operator extends from position -5 just upstream of the mRNA start point to position +21 within the transcription unit.