Question

Gene and cistron words are sometimes used synonymously because –
A. One cistron contains many genes.
B. One gene contains many cistrons.
C. One gene contains one cistron.
D. One gene contains no cistron.

Answer 1

Hint: They are the structural units of the genome of an organism. A cistron is the sum of all the exons present in a single gene.

Complete answer:
A gene is a sequence of nucleotides in the genetic material of an organism. They code for either RNA or protein. The segment of DNA that is equivalent to a gene specifies a single functional unit. Cistron is a segment of DNA that codes for one polypeptide. Since each gene specifies a specific polypeptide so each gene is said to contain one cistron.
During gene expression, the DNA is first copied into RNA and then this RNA can be functional directly or can act as the intermediate template for a protein synthesis that performs a function. A gene can be monocistronic or polycistronic.
> Monocistronic mRNA is where only one gene is expressed from a promoter region. Each of them has its own promoter and terminator.
> Polycistronic mRNA is the one that encodes several proteins. It is characteristic of many bacterial and chloroplast mRNAs. Polycistronic mRNAs consist of a leader sequence that precedes the first gene. Here many genes are present per promoter region.

So, the correct answer is ‘One gene contains one cistron’.

Note: Some functions of Gene are-
1. They code for Protein which is one of the most important materials in the human body. Proteins are the building blocks for muscles, connecting tissue and skin. They also take care of the production of the enzymes. These enzymes play an important role in conducting various chemical processes and reactions within the body.
2. Genes consist of a particular set of instructions which are of specific functions. For example, the globin gene is instructed for the production of hemoglobin. Hemoglobin helps to carry oxygen in the blood.