In this article we will discuss about the various disciplines which have played an important role in rapid advancement in the field of genetics.
Cytology is the science which deals with the structure, composition and function of various cell organelles. Cytological studies have been instrumental in establishing the physical basis of heredity by discovering the nature and role of nucleus, cytoplasm and gene. The parallelism between chromosomes and genes helped in establishing the foundation of genetics.
Cytological proof of crossing over has helped in better understanding of the phenomenon of linkage and the discovery of sex chromosome has been fruitful in developing the concept of sex determination. The chromosomal aberrations have helped in locating the genes on chromosomes. Cytological studies on monosomics and nullisomics have been useful in locating the genes on different chromosomes.
Biochemical studies have played a significant role in the advancement of the science of genetics.
Various concepts of genetics, viz:
(1) One gene one enzyme hypothesis,
(2) Regulation of gene action,
(3) Discovery of DNA as genetic material,
(4) Artificial synthesis of gene, etc., have been discovered with the help of biochemical studies. Bacteria especially E. coli and viruses particularly bacteriophages have been useful in the development of biochemical genetics.
The role of biophysics is also remarkable in the advancement of genetical research. The X-ray diffraction studies of Wilkins proved crucial for the discovery of the molecular structure of DNA.
Modern biophysical equipment’s, such as, electron microscopes and methods such as auto-radiographs (images on photographic emulsions produced by the variable distribution of radioactive material in a specimen) have aided greatly in the studies of chromosomes and genetic material.
Statistics has helped in developing the field of quantitative genetics. The concept of polygenic inheritance is now one of the most important principles of genetics. This concept has been strengthened greatly by the use of statistical methods. Fisher (1918) in England and Wright (1921) in United States provided a mathematical basis for the genetic interpretation of quantitative or polygenic characters.
Statistical tests are used as tools for testing the significance of differences between observed and expected frequencies (x2 test) and in testing the differences between sample mean and population mean (t test and z test) as well as among various treatment means (F test).
Hardy, an English mathematician and Weinberg, a Cerman physician independently discovered a principle concerned with the frequencies of genes'(alleles) in a population. This has led to the development of the concept of population genetics (Hardy-Weinberg law).