What is a gene? 2. A question with variable answers

Abstract

The first part of this article traced the evolution of the concept of a gene from Mendel's times to the middle of this century: starting from the imaginaryfactors of Mendel, thegenes were shown, in the first few decades of this century, to be physical entities many of which were linked in a linear order on a single chromosome. Each of these were believed to be indivisible units of function, mutation and recombination. Subsequent studies in microorganisms as well as higher organisms revealed the gene to be divisible in all its properties. Theclassical concept of indivisible gene thus gave way to something with a more complex organization. The advent of molecular biology allowed more detailed studies on the organization of the gene and the way it functions. In keeping with the remarkable diversity and complexity of biological systems, thegene has also turned out to be equally diverse and fascinating.