One gene, one polypeptide hypothesis

The one-gene-one-polypeptide hypothesis is a further development of the one-gene-one-enzyme hypothesis .

According to the “one-gene-one-enzyme hypothesis”, the concept of the gene , introduced by Wilhelm Johannsen in 1909 , is a classic conception of a functional unit by which a characteristic is determined. A little later, a gene was viewed as a mutation unit and as an exchange unit in crossing-over . A gene was considered to be a section of DNA that encoded a specific protein or enzyme .

However, modern molecular biology has led to a change in the meaning of the term gene: a term based on the "one-gene-one-polypeptide hypothesis" was first introduced, which replaces the old one based on the "one gene-one enzyme hypothesis" based, term temporarily replaced. This was a consequence of the newly gained knowledge:

• Proteins can consist of several polypeptides ; therefore, any stretch of DNA that codes for a polypeptide can be considered a gene.

Today it is known that such a gene can be read in different ways by alternative splicing ; this means that a gene can now code for several polypeptides, which are also known as isoforms .

However, genes can not only code for polypeptides via mRNAs , but variants of their transcripts can represent other, likewise functional RNAs , for example rRNA , tRNA or XIST-RNA . Therefore, today a gene is defined as a section of the chromosome to which the formation of certain functional gene products can be traced back.