Molecular genetics is a sub-speciality of biology that marks how variation in the structures or expression of DNA molecules indication as variation among organisms. By using mutagenesis screen molecular genetics frequently applies an "investigative approach" to determine the structure or function of genes in an organism's genome. The field of study is based on the consolidation of several sub-fields in biology: classical Mendelian inheritance, cellular biology, molecular biology, biochemistry, and biotechnology. Molecular genetics is a robust methodology for linking mutations to genetic conditions that may support the search for treatments/cures for various genetics diseases.