Chromosomal Mosaicism in the Human and Chromosomal Change in vitro

Abstract

Cellular activities can be regulated by mechanisms which stimulate or inhibit the enzymes already existing in the cell, or stimulate or inhibit their synthesis. Largely on the basis of findings in microbiology, the control of enzymatic patterns of activities in the life cycle of the cell is considered to involve, at least in part, regulation of enzyme synthesis at a genetic level [1]. As the scheme in Fig. i shows, each DNA molecule is responsible for the synthesis of a corresponding RNA molecule (the “messenger”) which carries the information of the gene for the correct orientation of amino acids in the synthesis of specific protein. Whether a particular DNA sequence is active or not is determined by its trigger—the “operator” gene. Normally, the operator is repressed by a “repressor” substance produced by a “regulator” gene. Specific materials (perhaps including hormones [2]) which can inhibit the action of the repressor substance will allow the operator trigger to function and start transcription of the DNA strand. The regulation, or playing of the keyboard of genes, during the cell life cycle is so envisaged.