Genetics is the study of the inheritance and variation of biological traits. We have previously noted that it is possible to conduct genetic research without directly studying DNA. Indeed some of the greatest geneticists had no special knowledge of DNA at all, but relied instead on analysis of phenotypes, inheritance patterns, and their ratios in carefully designed crosses. Molecular biology is a different set of techniques that involve the study of DNA and other macromolecules that have been isolated from an organism. Today, classical genetics is often combined with molecular biology, to give molecular genetics. Usually, molecular genetics experiments involve some combination of techniques to isolate, then analyze the DNA or RNA transcribed from a particular gene. In some cases, the DNA may be subsequently manipulated by mutation or by recombination with other DNA fragments. Techniques of molecular genetics have wide application in many fields of biology, as well as forensics, biotechnology, and medicine.