Bissoy.com
Doctors Medicines MCQs Q&A

In the absence of Lactose, what is expected to happen according to lac operon model ?

In the absence of Lactose, what is expected to happen according to lac operon model ? Correct Answer Repressor protein binds to the operator site

Concept-

  • Gene expression is the mechanism at the molecular level by which a gene can express itself in the phenotype of an organism.
  • The mechanism that stimulates the expression of certain genes and inhibits that of others is called the regulation of gene expression.
  • Francis Jacob and Monod proposed a mechanism called the operon model for the regulation of gene action in E.coli.
  • An operon is a part of genetic material that acts as a single regulated unit having one or more structural genes, a promoter gene, a regulator gene.
  • Operons are of two types- inducible and repressible.
  • The best-known operon is lac operon.

Explanation-

Additional Information

  • In the presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer.
  • This allows RNA polymerase access to the promoter and transcription proceeds.
  • Essentially, regulation of lac operon can also be visualized as regulation of enzyme synthesis by its substrate. 

Related Questions

The lac operon is found only in prokaryotes and consists of structural genes and a promoter and operator. Which of the following statements explains why we study the lac operon?
The investigation of the lac operon for the metabolism of lactose was done by __________
We know that lactose has a positive impact on the activity of the lac operon. Tryptophan’s presence has a ________________
What will be the binding status of regulatory proteins in lac operon when concentrations of both lactose and glucose are very low in the culture medium?
The lactose (lac) operon of the bacterium E. coli has which of the following structural genes?
The synthesis of new proteins necessary for lactose utilization by the bacterium E. coli using the lac operon is regulated
If the lac operon of the genome of bacteria is always active it has a defect in which region of the operon?
If there is an insertion mutation in the operator of the lac operon, the expression of the lac structural gene will be __________
The Weberian model of bureaucracy has been criticised from a variety of stand points.
Consider the following points in this regard:
1. The Weberian model appears to be a 'machine theory' and a closed system model taking little account of organisational interactions with the environment.
2. The structural features of bureaucracy as laid down by Weber might be suitable for routine and repetitive tasks but these would produce dysfunctional consequences in terms of human behaviour if the jobs would involve innovation and creativity.
3. Weberian model has not been found to respond adequately to the tasks of socioeconomic transformation in the developing countries. These tasks require quick changes whereas the capacity of the Weberian model for adaptation to change is rather slow.
4. Weber's model is confined to the study of formal bureaucratic structure and fails to take notice of the informal structure of bureauracy such as informal relations, informal norms and values, an informal power hierarchy and informal power struggles.
Which of the above points make a valid criticism of the Weberian model? Select the correct answer from below:
Lac, a scarlet resinous secretion of tiny insects referred to as lac insects, which produces a gum like secretion used in the production of various commodities such as gums, dyeing fabrics, bangle making, wood polishing etc. Which of the following state is the largest producer of LAC in India?