Explainer: The Basics of DNA and Genetic Systems

While there is great diversity among living things, we all have one thing in common—we all rely on a genetic system made up of DNA and/or RNA.

But how do genetic systems work, and to what extent do they vary across species?

This graphic by Anne-Lise Paris explores the basics of DNA and genetic systems, including how they’re structured, and how they differ across species.

Composition of Genetic Systems: DNA and RNA

A genetic system is essentially a set of instructions that dictate our genetic makeup—what we look like and how we interact with our environment.

This set of instructions is stored in nucleic acids, the two main types being deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

While most living things rely on a mix of DNA and RNA for cellular reproduction, some viruses just use RNA to store their genetic information and replicate faster.

DNA is made up of four molecules, known as nucleotides: Adenine (A), Thymine (T), Cytosine ( C), and Guanine (G). These nucleotides are grouped in sets of two, which are called base pairs.

Size of Genomes Across Different Organisms

Human DNA is made up of approximately 3.2 billion base pairs that are tightly wound up and stored in our cells. If you were to unwind and measure the DNA stored in a single human cell, it would be about 2 meters (6.5 feet) long!

This lengthy DNA is stored in pairs of chromosomes. (Read more...)