What Do You Mean By Monocistron And Polycistron
When we define a gene, it is considered as the functional unit of inheritance. So, what is a gene? Well, it is the DNA sequence that codes for a polypeptide. We can thus call a gene as the DNA sequence that codes for tRNA, rRNA, and mRNA.
We know that only mRNA sequence is translated to produce polypeptides. It is therefore, important to give a special name to the DNA sequence that codes for mRNA and eventually proteins. We call it as CISTRON. We can define CISTRON as a DNA sequence that codes for a polypeptide.
In case of EUKARYOTES, we know that a gene codes for a single polypeptide, and therefore, we can call a CISTRON as MONOCISTRONIC in eukaryotes. On the other hand, when we talk about prokaryotes, we know that structural genes (a combination of genes in tandem) code for more than one polypeptide. So, we can call a CISTRON as POLYCISTRONIC in prokaryotes.
It is also important to mention that in eukaryotes, coding DNA sequences are interrupted by non-coding sequences. And we use special terms such as EXON (coding sequence) and INTRON (non-coding sequence).
Note: In prokaryotes, non-coding sequences (INTRONS) are absent.
We know that only mRNA sequence is translated to produce polypeptides. It is therefore, important to give a special name to the DNA sequence that codes for mRNA and eventually proteins. We call it as CISTRON. We can define CISTRON as a DNA sequence that codes for a polypeptide.
In case of EUKARYOTES, we know that a gene codes for a single polypeptide, and therefore, we can call a CISTRON as MONOCISTRONIC in eukaryotes. On the other hand, when we talk about prokaryotes, we know that structural genes (a combination of genes in tandem) code for more than one polypeptide. So, we can call a CISTRON as POLYCISTRONIC in prokaryotes.
It is also important to mention that in eukaryotes, coding DNA sequences are interrupted by non-coding sequences. And we use special terms such as EXON (coding sequence) and INTRON (non-coding sequence).
Note: In prokaryotes, non-coding sequences (INTRONS) are absent.
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