What is the science of Genetics?

Genetics is the field of science that examines how traits are passed from one generation to the next. Simply put, genetics affects everything about every living thing on earth. An organism’s genes, snippets of DNA that are the fundamental units of heredity, control how the organism looks, behaves, and reproduces. Because all biology depends on genes, understanding genetics as a foundation for all other life sciences, including agriculture and medicine, is critical.

From a historical point of view, genetics is still a young science. The principles that govern inheritance of traits by one generation from another were described (and promptly lost) less than 150 years ago. Around the turn of the 20th century, the laws of inheritance were rediscovered, an event that transformed biology forever. But even then, the importance of the star of the genetics show, DNA, wasn’t really understood until the 1950s. Now, technology is helping geneticists push the envelope of knowledge every day.

The Branches of the Science

Classical Genetics
A discipline that describes how physical characteristics (traits) are passed along from one generation to another.
Quantitative Genetics
A highly mathematical field that examines the statistical relationships between genes and the traits they encode.
Molecular Genetics
The study of the chemical and physical structures of DNA, its close cousin RNA, and proteins. Molecular genetics also covers how genes do their jobs.
Population Genetics
A division of genetics that looks at the genetic makeup of larger groups.
Whereas all the above fields are important to a geneticists everyday life, human genetic engineering exists mostly in the realm of classical and molecular genetics and it is those two branches that we will aim to get you familiarised with.

Classical Genetics

Transmitting traits from generation to generation

At its heart, classical genetics is the genetics of individuals and their families. It focuses mostly on studying physical traits, or phenotypes, as a stand-in for the genes that control appearance.

Gregor Mendel, a humble monk and part-time scientist, founded the entire discipline of genetics. Mendel was a gardener with an insatiable curiosity to go along with his green thumb. His observations may have been simple, but his conclusions were jaw-droppingly elegant. This man had no access to technology, computers, or a pocket calculator, yet he determined, with keen accuracy, exactly how inheritance works.

No matter what you call it, classical genetics includes the study of cells and chromosomes. Cell division is the machine that drives inheritance, but you don’t have to understand combustion engines to drive a car, right? Likewise, you can dive straight into simple inheritance and work up to more complicated forms of inheritance without knowing anything whatsoever about cell division. (Mendel didn’t know anything about chromosomes and cells when he figured this whole thing out, by the way.)

Molecular Genetics

DNA and the chemistry of genes

Classical genetics concentrates on studying outward appearances, but the study of actual genes falls under the heady title of molecular genetics. The area of operations for molecular genetics includes all the machinery that runs cells and manufactures the structures called for by the plans found in genes. The focus of molecular genetics includes the physical and chemical structures of the double helix, DNA. The messages hidden in your DNA (your genes) constitute the building instructions for your appearance and everything else about you — from how your muscles function and how your eyes blink to your blood type, your susceptibility to particular diseases, and everything in between.

Your genes are expressed through a complex system of interactions that begins with copying DNA’s messages into a somewhat temporary form called RNA. RNA carries the DNA message through the process of translation, which, in essence, is like taking a blueprint to a factory to guide the manufacturing process. Where your genes are concerned, the factory makes the proteins (from the RNA blueprint) that get folded in complex ways to make you.