Question
Define an operon. Giving an example, explain an Inducible operon.
✓
Answer
A functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter is called an operon. An operon is generally transcribed into polycistronic mRNA. A single mRNA which codes for more than one protein is called polycistronic mRNA. An operon is made up of 3 basic DNA components:
i. Promoter: A nucleotide sequence that enables a gene to be transcribed is called a promoter. It is recognized by RNA polymerase, which then initiates transcription.
ii. Operator: A segment of DNA to which a repressor binds is called the operator.
iii. Structural genes: The genes that are co-regulated by the operon are called structural genes. Inducible Operon: When the operon is regulated by an inducer, it is called an inducible operon. An inducer can switch on or off the operon. Lac operon is an example of an inducible operon. Lactose is a substrate of enzyme beta-galactosidase and is the inducer of the lac operon.
The given diagram shows the working of the lac operon. In the absence of an inducer, the repressor binds to the operator region and prevents transcription.
In the presence of an inducer, repressor becomes inactive. This allows transcription in the operator region which results in the release of mRNA. Subsequently, mRNA promotes translation and protein synthesis is accomplished
i. Promoter: A nucleotide sequence that enables a gene to be transcribed is called a promoter. It is recognized by RNA polymerase, which then initiates transcription.
ii. Operator: A segment of DNA to which a repressor binds is called the operator.
iii. Structural genes: The genes that are co-regulated by the operon are called structural genes. Inducible Operon: When the operon is regulated by an inducer, it is called an inducible operon. An inducer can switch on or off the operon. Lac operon is an example of an inducible operon. Lactose is a substrate of enzyme beta-galactosidase and is the inducer of the lac operon.
The given diagram shows the working of the lac operon. In the absence of an inducer, the repressor binds to the operator region and prevents transcription.
In the presence of an inducer, repressor becomes inactive. This allows transcription in the operator region which results in the release of mRNA. Subsequently, mRNA promotes translation and protein synthesis is accomplished
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
- Draw a labelled diagrammatic view of human male reproductive system.
- Differentiate between:
- Vas deferens and Vasa efferentia.
- Spermatogenesis and spermiogenesis.
(A)What is immunity and how many types are there?
(B) Write a brief note :-
(1) Auto immune disease$\quad$$\quad$(2) Allergy
→(B) Write a brief note :-
(1) Auto immune disease$\quad$$\quad$(2) Allergy
State the hypothesis proposed by Oparin and Haldane. Describe how S.L. Miller experiemen-tally supported it.###Describe the experiment of S.L. Miller. Comment upon his contribution in origin of life on earth, on the basis of experiments and observations.
Describe the steps involved in the sequencing of genome of an organism.
Draw a neat diagram of the female reproductive system and label the parts associated with the following.
- Production of gamete.
- Site of fertilisation.
- Site of implantation.
- Birth canal.
Name the modern technology of crop improvement. How is it beneficial in crop improvement? Explain. ###Write an essay on tissue culture.
Suggest some methods to assist infertile couples to have children.
Write a short note on :
(a) Adaptations of desert plants and animals.
(b) Adaptations of plants to water scarcity.
(c) Behavioural adaptations in animals.
(d) Importance of light to plants.
(e) Effect of temperature or water scarcity and the adaptations of animals.
(a) Adaptations of desert plants and animals.
(b) Adaptations of plants to water scarcity.
(c) Behavioural adaptations in animals.
(d) Importance of light to plants.
(e) Effect of temperature or water scarcity and the adaptations of animals.
The following is the illustration of the sequence of ovarian events (a – i) in a human female.
How does replication of the long DNA molecule occur? Explain the process.
OR
Explain the process of DNA replication with the help of a replicating fork.