Duplex theory proposes that the human genome is composed of two distinct types of elements, namely euchromatin and heterochromatin. The two types of chromatin are thought to be responsible for different functions and are believed to interact in complex ways to orchestrate gene expression and other cellular processes. This theory has been controversial since its introduction in the early 1900s, as it challenges the traditional view that genetic information is solely contained in DNA sequences. In this review, we discuss the evidence for and against duplex theory and how the concept has evolved over time.
The concept of duplex theory was first proposed by Arthur D. Sturtevant in 1910. His initial hypothesis was that euchromatin and heterochromatin were two distinct forms of chromatin and that they had different roles in gene expression and other cellular processes. In the decades since, this theory has been further refined and developed, and it currently serves as a basis for understanding the complex interplay between DNA and other cellular components.
The evidence for duplex theory is largely based on observations of gene expression and epigenetic modifications. For example, it has been shown that heterochromatin can be associated with gene silencing while euchromatin can be associated with gene activation. Additionally, changes in the structure and organization of chromatin can affect gene expression. For example, certain epigenetic modifications can alter the structure of chromatin and in turn, affect gene expression.
Despite the evidence for duplex theory, some researchers have proposed alternative theories of gene regulation. For example, the “one gene-one protein” theory proposes that gene expression is determined solely by the DNA sequence, and does not involve other cellular components. Additionally, some researchers have proposed that gene expression can be regulated by non-coding RNA molecules.
Overall, duplex theory remains a controversial concept. However, it is clear that the organization and structure of chromatin play an important role in gene expression and other cellular processes. As our understanding of the complexity of the genome continues to develop, it is likely that our view of duplex theory will also evolve.
References
Sturtevant, A.D. (1910). The duplex theory of the gene. The American Naturalist, 44(517), 517-532.
Peters, A.H.F. (2006). The basics of epigenetics. Molecular Genetics and Metabolism, 89(1-2), 9-19.
Wang, T. & Zhang, Y. (2015). Non-coding RNAs and gene regulation. Protein & Cell, 6(6), 439-451.