The study of genetics expanded greatly and quickly from that moment on. The first gene was sequenced in 1972 and both Richard Roberts and Phillip Sharp showed that genes could themselves be split in 1977. This furthered the concept that one gene could make several types of proteins. Genomes began to be sequenced and it was understood that certain genes could overlap with other genes. The genomics era of genetics started in 1972 when the first gene was sequenced and continues today. Gene mapping was identified in 1980, which was also when the first US patent was awarded for gene cloning. The first genetically engineered insulin was approved in 1982 and the practice of polymerase chain reaction was invented in 1983, which is now used for DNA amplification in the diagnosis of infectious diseases. In 1985, DNA fingerprinting techniques were created using chemical probes to examine DNA between different humans. By 1989, the CFTR gene that led to cystic fibrosis was first sequenced. Soon afterward, it became possible to use amniocentesis to identify hemophilia, cystic fibrosis, and other diseases in utero. The first breast cancer gene, called BRCA1 was discovered in 1994, followed closely by the identification of the second breast cancer gene, called BRCA2. The first cloned sheep was born in 1997. The Human Genome Project to sequence human DNA was completed in 2003.
CATEGORIES OF GENETIC STUDY We have touched briefly already on the three major branches of genetics, which are classical genetics, molecular genetics, and population genetics. There are several areas of genetic study that are considered minor branches, such as behavioral genetics, developmental genetics, genetic engineering, genomics, human and medical genetics, microbial genetics, and psychiatric genetics. Let’s look at the three major branches studied today. In classical genetics, research is based on the visible results of sexual reproduction. It dates back from the time of Gregor Mendel but has been expanded so it is understood now at a molecular level. At its heart is the concept of a gene being the basic unit of genetic transmission and on the idea that organisms are diploid, meaning they have two alleles of which one comes from the mother and one comes from the father.
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