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Explainer: The Basics of DNA and Genetic Systems

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Explainer of DNA and Genetic Systems

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. A full collection of chromosomes, or an entire set of genetic information, is referred to as a genome.

Genomes vary in size, depending on the organism. Here is a look at 24 different species and the size of their genomes, from animals and plants to bacteria and viruses:

OrganismKingdomSize of genomes (number of base pairs)
Poplar treePlant500,000,000
HumanAnimal3,200,000,000
ChimpanzeeAnimal3,300,000,000
Marbled lungfishAnimal130,000,000,000
DogAnimal2,400,000,000
WheatPlant16,800,000,000
PufferfishAnimal400,000,000
Canopy plantPlant150,000,000,000
Mouse-ear cressPlant140,000,000
CornPlant2,300,000,000
MouseAnimal2,800,000,000
MossPlant510,000,000
Fruit FlyAnimal140,000,000
C. ruddiiBacteria160,000
S. pombeFungi13,000,000
S. cerevisiaeFungi12,000,000
S. cellulosumBacteria13,000,000
H. pyloriBacteria1,700,000
E. coliBacteria4,600,000
Panadoravirus s.Virus2,800,000
HIV-1Virus9,700
Influenza AVirus14,000
BacteriophageVirus49,000
Hepatitis D virusVirus1,700

The Marbled Lungfish has the largest known animal genome. Its genome is made up of 130 billion base pairs, which is about 126.8 billion more than the average human genome.

Comparatively, small viruses and bacteria have fewer base pairs. The Hepatitis D virus has only 1,700 base pairs, while E. coli bacteria has 4.6 million. Interestingly, research has not found a link between the size of a species’ genome and the organism’s size or complexity.

In fact, there are still a ton of unanswered questions in the field of genome research. Why do some species have small genomes? Why do some have a ton of redundant DNA? These are still questions being investigated by scientists today.

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This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.

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The Anthropocene: A New Epoch in the Earth’s History

We visualize Earth’s history through the geological timeline to reveal the planet’s many epochs, including the Anthropocene.

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The Anthropocene: A New Epoch in the Earth’s History

Over the course of Earth’s history, there have been dramatic shifts in the landscape, climate, and biodiversity of the planet. And it is all archived underground.

Layers of the planet’s crust carry evidence of pivotal moments that changed the face of the Earth, such as the ice age and asteroid hits. And scientists have recently defined the next major epoch using this geological time scale—the Anthropocene.

In this infographic we dig deep into the Earth’s geological timeline to reveal the planet’s shift from one epoch to another, and the specific events that separate them.

Understanding the Geological Timeline

The Earth’s geological history is divided into many distinct units, from eons to ages. The time span of each varies, since they’re dependent on major events like new species introduction, as well as how they fit into their parent units.

Geochronologic unitTime spanExample
EonSeveral hundred million years to two billion yearsPhanerozoic
EraTens to hundreds of millions of yearsCenozoic
PeriodMillions of years to tens of millions of yearsQuaternary
EpochHundreds of thousands of years to tens of millions of yearsHolocene
AgeThousands of years to millions of yearsMeghalayan

Note: Subepochs (between epochs and ages) have also been ratified for use in 2022, but are not yet clearly defined.

If we were to cut a mountain in half, we could notice layers representing these changing spans of time, marked by differences in chemical composition and accumulated sediment.

Some boundaries are so distinct and so widespread in the geologic record that they are known as “golden spikes.” Golden spikes can be climatic, magnetic, biological, or isotopic (chemical).

Earth’s Geological Timeline Leading Up to the Anthropocene

The Earth has gone through many epochs leading up to the modern Anthropocene.

These include epochs like the Early Devonian, which saw the dawn of the first early shell organisms 400 million years ago, and the three Jurassic epochs, which saw dinosaurs become the dominant terrestrial vertebrates.

Over the last 11,700 years, we have been living in the Holocene epoch, a relatively stable period that enabled human civilization to flourish. But after millennia of human activity, this epoch is quickly making way for the Anthropocene.

EpochIts start (MYA = Million Years Ago)
Anthropocene70 Years Ago
Holocene0.01 MYA
Pleistocene2.58 MYA
Pliocene5.33 MYA
Miocene23.04 MYA
Oligocene33.90 MYA
Eocene56.00 MYA
Paleocene66.00 MYA
Cretaceous145.0 MYA
Jurassic201.40 MYA
Triassic251.90 MYA
Lopingian259.50 MYA
Guadalupian273.00 MYA
Cisuralian300.00 MYA
Pennsylvanian323.40 MYA
Mississippian359.30 MYA
Devonian419.00 MYA
Silurian422.70 MYA
Ludlow426.70 MYA
Wenlock432.90 MYA
Llandovery443.10 MYA
Ordovician486.90 MYA
Furongian497.00 MYA
Miaolingian521.00 MYA
Terreneuvian538.80 MYA

The Anthropocene is distinguished by a myriad of imprints on the Earth including the proliferation of plastic particles and a noticeable increase in carbon dioxide levels in sediments.

A New Chapter in Earth’s History

The clearest identified marker of this geological time shift, and the chosen golden spike for the Anthropocene, is radioactive plutonium from nuclear testing in the 1950s.

The best example has been found in the sediment of Crawford Lake in Ontario, Canada. The lake has two distinct layers of water that never intermix, causing falling sediments to settle in distinct layers at its bed over time.

While the International Commission on Stratigraphy announced the naming of the new epoch in July 2023, Crawford Lake is still in the process of getting approved as the site that marks the new epoch. If selected, our planet will officially enter the Crawfordian Age of the Anthropocene.

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