In this article, the changing pattern of processes of differentiation will be shown in examples taken from the development of living organisms. Hemoglobins: How specific genes change their activity during development is illustrated by the composition of hemoglobins in man. The hemoglobin in adult humans is in the form of composite molecules consisting of four units (polypeptides), two of which [...]
When development starts the genes are in a repressed stage. During cleavage the genes are inactive (with the exception of histone genes), and whatever hereditary traits can be observed are due to gene action during the growth and maturation of the oocyte. From gastrulation onward, some genes become activated, and the action of individual genes becomes evident. By observing normal [...]
In this article we will discuss about the control of reactive ability of tissues by the genotype. While the initial step in the differentiation of cells is made by the cytoplasm, it can be shown that the final result cannot be achieved without the involvement of hereditary factors, the nuclear genes. This is true in particular in the case of [...]