Operon Concept

In lac operon, the lactose acts as

In the lac operon shown above, name the molecule ‘X’ synthesized by ‘i’ gene and name the molecule synthesised by the Z gene:

Proteins $\mathrm{P}1$ and $\mathrm{P}2$  bind to each other to form a complex. This complex has a high binding affinity to a specific element on the promoter sequence of a gene $\mathrm{X}$, thus transcribing it. The product of gene $\mathrm{X}$is responsible for the accumulation of red pigment in some plants. Under drought stress, another protein $\mathrm{P}3$ binds to $\mathrm{P}2$ and prevents its binding to $\mathrm{P}1$ and the plants appear pale. The following table depicts a representation of phenotypes of wild-type and mutant  plants.

Choose the correct statement(s).

In biological systems, proteins (repressors and activators) control gene expression. Repressors bind to promoters and inhibit gene expression. Some promoters require activators for gene expression. These constitute a genetic circuit and are analogous to logic gates in digital electronics. A schematic diagram of a genetic circuit in a cell is shown below. Binding of IPTG to LacI activates transcription from $P_{\mathrm{lac}}$. Binding of arabinose (Ara) to AraC activates transcription from $P_{\mathrm{ara}}$.

 The correct statement(s) regarding the given genetic circuit is/are

The Lac operon contains three structural genes ${}^{\text{'}}\mathrm{z}^{\text{'}},{\mathrm{y}}^{\text{'}}$ and ${}^{\text{'}}\mathrm{a}^{\text{'}}$ The structural genes code for
i) The $\text{'}\mathrm{z}\text{'}$ gene codes for beta-galactosidase enzyme.
ii) $\text{'}\mathrm{a}\text{'}$ gene does not code for transacetylase enzyme.
iii) The $\text{'}\mathrm{y}\text{'}$ gene codes for enzyme permease.
iv) $\text{'}\mathrm{y}\text{'}$' gene does not code for the enzyme permease.
v) $\text{'}\mathrm{a}\text{'}$ gene codes a transacetylase enzyme.
The correct combination is

Genetic information is passed from one generation to other through

In lac operon which is an inducible operon, non-constitutive gene/s is/are ___(i)___ and its regulation is controlled by ___(ii)___ .

In lac-operon, which protein is not regulated by the repressor?

The Lac operon gets switched on when

Lactose is the substrate for the enzyme ß-galactosidase and it regulates switching on and off of the operon. Hence, it is termed as

The regulation of gene expression in eukaryotes occurs at / or include

In prokaryotes, the regulation of gene expression occurs at

Lac operon consists of

I. Glucose or galactose may bind with the repressor and inactivate it.
II. In the absence of lactose, the repressor binds with the operator region.
III. The z-gene codes for permease.
IV. This was elucidated by Francois Jacob and Jacques Monod.

The correct statements are:

Which one of the following is incorrectly matched?

Match the following column I with column II and choose the option with the accurate matches.

In the lac operon model, lactose molecules function as

To which of the following, repressor protein is attached?

When lactose is the normal energy source in bacterial cell ___________ gene transcribes a repressor mRNA.

In the presence of glucose and lactose, Escherichia coli utilizes glucose. However, lactose also enters the cells because?