DNA's Building Blocks May Have Their Origins in Outer Space

By: Elizabeth Howell

One of life's building blocks could have originated in outer space. But if this experiment shows how these building blocks actually formed, how exactly did they get to Earth?

January 24, 2020

One of life's building blocks could have originated in outer space. Astronomers simulated the clouds of gas and dust that are strewn between stars out in the cosmos and found that their chemical reactions produced nucleobases: the building blocks of DNA. But if this experiment shows how these building blocks actually formed, how exactly did they get to Earth?

Where Did Life Begin?

We know that life is practically everywhere on Earth, from hydrothermal vents deep within the ocean to certain spacecraft clean rooms (you know, the ones that are supposed to be clear of bacteria). But how life became so prevalent on Earth is something that still stymies scientists. After all, if life is everywhere on Earth, shouldn't we see it easily on other planets or moons?

Some people suggest that maybe life was brought in from elsewhere — that comets or asteroids bearing life crashed into our planet, and that life spread. Others think that the chemistry of our own world had a particular mix of life-giving ingredients that somehow combined to become life. We don't know, so we study planets and moons all over the solar system to try to learn more. While we haven't found life anywhere but Earth, we continue the search with missions like NASA's Curiosity rover.

In particular, scientists are on the hunt for organic molecules. That's a class of molecules that can sometimes indicate life, depending on their composition. We've found organic molecules on Mars, for example, but we don't know yet if they came from life. To determine that, scientists need more sophisticated instruments that can search for aspects such as chirality, or the geometric shape of molecules, since some shapes are used more often by life than others. (Europe's forthcoming Rosalind Franklin rover may be able to achieve such a feat.)

Nucleotides! In! Space!

So this brings us to nucleotides, which are basic units of DNA. DNA is where human bodies (and other organisms) store their genetic material. It's because of DNA that parents can pass on traits like eye color and handedness to their children. Nucleotides are the things that link up to form the famous spiral ladder shape, or "double helix," in the DNA molecule.

For an article published in the journal Nature Communications, a group of Japanese scientists led by Yahuiro Oba found nucleotides after simulating an interstellar cloud using a vacuum chamber. The chamber simulates the conditions of space — namely, no air, cold temperatures, and a harsh radiation environment.

The group fed water, carbon monoxide, ammonia, and methanol into a substance that acted as an analog for cosmic dust and observed the results at an ultra-chilling minus 263 degrees Celsius (minus 441.4 degrees Fahrenheit) — just a little bit above absolute zero, or the coldest temperature possible.

Next, the scientists used deuterium discharge lamps to mimic the ultraviolet light that stars are regularly radiating out into interstellar clouds. That was designed to trigger the same kinds of chemical reactions you'd find in space. In the end, the reactions formed an icy film that coated the dust. Once they had warmed the dust to room temperature and analyzed its contents, scientists detected several types of nucleobases, as well as amino acids (the building blocks of proteins, another important ingredient for life.)

This mixture probably showed up in other experiments, but the scientists think this is the first time it was detected because they used more advanced tools than before.

"Our findings suggest that the processes we reproduced could lead to the formation of the molecular precursors of life," said Oba in a statement. "The results could improve our understanding of the early stages of chemical evolution in space."

This article first appeared on Curiosity.com.

Next Up

The Perseid Meteor Shower Reaches its Peak

Stargazers rejoice! The annual Perseid meteor shower is upon us. Here's what you need to know...(updated August 11, 2022)

Scientists Have Discovered Enormous Balloon-Like Structures in the Center of Our Galaxy

There's something really, really big in the middle of our Milky Way galaxy — one of the largest structures ever observed in the region, in fact.

How to Watch the Orionids Meteor Shower in 2021

If you've seen a shooting star on a recent stargazing jaunt, you've spotted the very beginning of the Orionids meteor shower. It happens every fall in October or early November, and peak viewing hours are coming soon to skies near you.

Astronomers May Have Found a Rare “Free-Floating” Black Hole

How do you see a perfectly black object in the middle of a pitch-dark night? It sounds like the start of an annoying riddle, but it’s really the question faced by astronomers when they want to search for black holes.

Saving Earth from Killer Asteroids

Only about 40% of an estimated 25,000 near-Earth asteroids with the potential to destroy the planet have been detected. Scientist Dr. Ed Lu, along with his nonprofit B612 are working to create a way to detect the other 60%.

How Do We Know How Old the Sun Is?

Scientists estimate that our Sun is about 4.57 billion years old. They’re surprisingly confident about that number, too, which opens up an immediate question: how do we know that? The short answer is “a lot of science and math”, but I have a feeling you’re not here for the short answer.

Scientists in China Discover Rare Moon Crystal that Could Power Earth

A rare lunar crystal found on the near side of the moon is giving scientists hope of providing limitless power for the world – forever.

NASA's Biggest 2021 Milestones

From making history on Mars to supersonic aircraft, NASA continues to astound us with science from this past year.

William Shatner is going where no 90-year-old has gone before

The Star Trek star will become the oldest person to go to space when he launches aboard a Blue Origin rocket on Wednesday, October 13. Watch live coverage on Space Launch LIVE: Shatner in Space on Discovery and Science Channel starting at 8:30A ET with liftoff scheduled for 10A ET.

Space Launch LIVE Discussion Guide

Tune into Discovery Channel and use this companion discussion guide to spark meaningful conversation about the next era of space flight. Stream SPACE LAUNCH LIVE on discovery+.

Related To: