Genetics

Genetics is a branch of the science of biology whose main focus is the most fundamental unit of all biological life: the gene and the DNA molecule.

All living things are composed of DNA (deoxyribonucleic acid) housed safely in the nucleus of every cell. The DNA molecule stores all the biological code of a life-form as genes – sequences of living molecules – within its structure. This code contains the biological information necessary for the reproduction of life, the functioning of a living thing, and plays a central role in the replication of cells through which process it passes hereditary traits from parent to offspring in all living creatures.

The gene is the basic unit of biological information, units or heredity. Genes are stored within DNA as chains of nucleotides. As such the study of genetics is primarily concerned with the study of genes, genetic variation, and hereditary traits.

Modern genetics with the benefit of superior understanding and technology has evolved to specifically study the function, structure, distribution, variation and behavior or genes on ever more subtle levels. This has resulted in the emergence of a number of sub-fields within the sub-discipline of genetics such as molecular genetics, epigenetics, and population genetics.

A Brief History of Genetics

The concept of heredity – the inheritance of traits an offspring of some creature or plant receives from its parents has been known since prehistoric times. Once humans domesticated animals – sheep, dogs, cattle – along with various plants – grains, fruits, and vegetables – around 10,000 BCE they would have noticed how the offspring inherit traits from their parents.

In the people of their tribe, this would be evident as well. A boy would be built by her father, a daughter might have her mothers eyes, they might even share temperament or innate talents. These were noticed by ancient people who applied this understanding in the conscious development of desired traits in what we now call the genetic line through a technique known as selective breeding. The intentional combination of parents with desired traits in order to produce plant or animal offspring with the desired traits, which improved both plant and animal, at least in the eyes of the agriculturalist. Though it was a further 10 millennia until we could understand this on a technical level.

Modern genetics begins with the work of Gregor Mendel [1822-1884] who studied inheritance using pea plants. He traced inheritance patterns within the familial lines of pea plants by following specific traits passed down through the lineage, even using mathematics to describe them. His work was ahead of its time. Consequently it was not fully understood until around 1900, almost two decades after his death, when it was rediscovered by other scientists such as Hugo de Vries.

The term genetics was coined by William Bateson in 1905 from the Greek word γενετικός (genetikos) which means “generative” which itself stems from the word γένεσις (genesis) which means origin. It was first used specifically in association with the study of inheritance.

At its most fundamental level inheritance occurs by passing discrete units of heredity which we today call genes. The trait of heredity began to be studied intensively by rigorous scientific standards with the resurgence of Gregor Mendel’s work beginning around 1900. Over the intervening decades a great deal of knowledge was earned, refining our understanding of life at ever more subtle levels towards a molecular understanding.

With the amplification of our optical sense through the technology of a microscope, we began to see smaller levels of reality more clearly. It was known that genes existed on chromosomes, though as chromosomes are composed of both proteins and DNA, it wasn’t immediately clear whether proteins or DNA contained genetic information. It was not known until 1943, for example, that the nucleus of the cell stores genetic information in the form of DNA, nor until 1944 that the DNA molecule was proven to be responsible for gene transmission.

James Watson and Francis Crick discovered the dual helix geometric structure of the DNA molecule in 1953. This event was an important milestone within the sub-field of molecular biology, just as it was for the world. The found the structure by studying X-ray Crystallography of DNA, work done by Rosalind Franklin and Maurice Williams, which opened up the doorway to nearly unlimited possibilities, and questions, which we are still wrestling with today.

DNA and Chromosomes :: The Foundation of Genetics

The fundamental mechanism of this transmission of hereditary traits has only begin to be understood since the discovery of DNA structure in 1953. This discovery followed the discovery that the nucleus of the cell stores DNA, and that DNA stores genetic information and is responsible for gene transmission. Though it was the discovery of the structure of DNA which set the stage for understanding this mechanism on a precise level.

When a creature produces offspring from a male-female pair, each parent provides a strand of their DNA. The child receives roughly half their genome from their father, and half from their mother, passing on traits that are both physical, behavioral, and perhaps even related to talents, abilities, and deep ancestral knowledge, according to some.

An understanding of what are now the basics of modern genetics is founded in DNA. With it comes the modern branch of genetics called Molecular Genetics, which deals with biology at this scalar level of resolution. DNA (deoxyribonucleic acid) is the molecular basis of genes. DNA is composed of a chain of organic molecules called nucleotides, of which there are 4 types: adenine (A), cytosine (C), guanine (G), and thymine (T).

All genetic information is stored in the sequence of these nucleotides, which are in themselves living things, organic molecules which obey the Properties of Life. Genes then are the stretches of nucleotide sequence along the DNA molecule.

DNA exists under normal circumstances as a double-stranded molecule, coiled together into the shape of a double-helix. Like a corkscrew, the threading on a screw, or like the coiled-snake iconography in so many ancient cultures, from whence the caduceus symbol of the medical field is derived.

Each strand of DNA is identical to the other. During the process of DNA replication the DNA will split in two with each strand serving as a template from which an exact copy will be made, so that it can return to its preferred dual-helix coiled structure once again.

Further Reading

1. Popular Reading
   1. Genetics | Wikipedia | Accessed 10 Sept 2020
2. Scholarly Reading