Delving Into Genetics

Ever wondered about the term „genetic makeup“? Picture it as a detailed diary, documenting information about an individual – from their appearance and how their body operates to certain behavioral tendencies. This diary, known as the genome, is akin to an expansive cookbook found in almost every cell of a person. This cookbook is organized into sections or chapters, which we refer to as chromosomes. Each chapter holds unique recipes – these are our genes. They determine specific components or enzymes in our cells, influencing characteristics such as the color of our hair or eyes.

Intriguingly, every individual inherits two of these comprehensive cookbooks. One is a gift from the mother, sourced from the egg, and the other from the father, originating in the sperm. Each of these cookbooks holds a collection of 23 chapters, or chromosomes (labeled as 1n). Upon the union of these reproductive cells, a fertilized egg emerges, marking the inception of a new individual with a full set of 46 chromosomes (2n). All successive cells of this being will carry this complete set (2n), save for the reproductive cells, which maintain a set of 23 chromosomes (1n) just like those of our parents. While every chromosome set carries the same gene recipes, the ingredients (or the gene variants) might vary. Which variation, or allele, gets expressed can be quite fascinating. Take, for instance, eye color—it’s shaped by multiple genes and the unique combination of alleles inherited from both parents.

The Elegant Simplicity of Genetic Encoding

At the heart of our genes lies an intricate yet surprisingly straightforward code: our DNA, or deoxyribonucleic acid. Though the DNA structure is lengthy, its design is remarkably elementary. Using only four „letters,“ it records all the information required to build and maintain an organism.

These „letters“ nestle within our chromosomes and are the fundamental building blocks called nucleotide bases. In our genetic alphabet, these bases are denoted by A, C, G, and T, representing adenine, cytosine, guanine, and thymine, respectively. Astonishingly, our genome houses about 3.3 billion of these bases. Their specific arrangement crafts the unique code for every individual gene. And within us, there are over 20,000 such distinct genes.

The hereditary information in humans isn’t only found in the form of chromosomes located in cell nuclei (referred to as nuclear DNA). We can also find it in what is called mitochondrial DNA, a very short, circular molecule located within the mitochondria, which are essentially the cell’s energy factories. A unique characteristic of mitochondrial DNA is that it is almost exclusively inherited from the mother, not the father. Human mitochondrial DNA contains a mere 16.6 thousand nucleotide bases and encodes a minimal number of genes.

Interesting Facts

1. If we were to stretch out the entire genome of a single human cell into a straight line, it would measure over two meters in length. If we stretched out the DNA from all cells in a human body, the total length would be approximately four times the distance between the Earth and the Sun.
2. The genomes of two unrelated people differ by roughly one-tenth of a percent. This means that out of the mentioned 3.3 billion nucleotide bases, approximately 3.3 million are different. This accounts for the variations in appearance, physiology, predispositions to various diseases, and so on, among people. If we look at chimpanzees, our closest living relatives, we find that our DNA differs from theirs by approximately three percent.
3. DNA in cells appears in the form of a double helix, with nucleotide bases connecting the two strands. They pair up according to a specific rule: adenine always with thymine (A+T) and guanine always with cytosine (G+C). This pairing can be observed in DNA illustrations, as well as in the color scheme of the entire exhibition’s design.