Some of life’s key building blocks, known as nitriles, have been discovered by scientists in the very heart of our Milky Way galaxy.
They were discovered in a molecular cloud of gas and dust by a team of international researchers using two telescopes in Spain.
Nitriles are essential building blocks for RNA, a DNA-like nucleic acid found in all living cells.
The experts said their discovery suggests that nitriles are among the most abundant chemical families in the universe, supporting the “RNA World” theory of the origin of life.
This suggests that life on Earth was originally based only on RNA, while DNA and protein enzymes evolved later.
RNA can perform both of its functions: storing and copying information, like DNA, and catalyzing reactions, like enzymes.
According to the RNA World theory, nitriles and other building blocks for life do not have to originate on Earth itself.
Discovery: Some of life’s key building blocks, known as nitriles, have been discovered by scientists in the heart of our Milky Way galaxy. They were discovered in a molecular cloud of gas and dust (similar to this one in the photo) by a group of international researchers.
The experts said their discovery suggests that nitriles are among the most abundant chemical families in the universe, supporting the “RNA World” theory of the origin of life. This suggests that nitriles could originate in space and hitchhike to the young Earth inside meteorites and comets (archive image).
LIFE ON EARTH ARISED THANKS TO A MODIFIED VERSION OF MODERN RNA
Scientists believe that life on Earth could have originated thanks to a modified version of a related molecule of modern DNA.
DNA is the basis of life, and almost our entire planet depends on it, but on ancient Earth, a primitive version of its lesser-known sister, RNA, was the focus of evolution, experts say.
RNA is structurally similar to DNA, except that one of the four main parts, thymine, is replaced by uracil.
This changes the shape and structure of the molecule, and researchers have long believed that this chemical was vital to the development of the first life forms on Earth.
An accidental discovery by Harvard scientists published in December 2018 showed that a slightly different version of RNA could be the key ingredient that allowed life to flourish on Earth.
Scientists say that instead of guanine, a chemical called inosine could have been present, which allowed life to develop.
This small change in bases, known as nucleotides, could be the first known evidence for the “RNA World Hypothesis,” a theory that claims that RNA was an integral part of primitive life forms, they say.
They may also have originated in space and hitchhiked to the young Earth inside meteorites and comets during the Late Heavy Bombardment, between 4.1 and 3.8 billion years ago.
In support of this, nitriles and other precursor molecules of nucleotides, lipids, and amino acids have been found inside recent comets and meteors.
The question is, where in space could these molecules come from?
The first candidates are molecular clouds, which are dense and cold regions of the interstellar medium and are suitable for the formation of complex molecules.
For example, the molecular cloud G+0.693-0.027 has a temperature of about 100 K and a diameter of about three light years, and its mass is about a thousand times that of our Sun.
There is no evidence that stars are currently forming within G+0.693-0.027, although scientists suspect it could become a stellar nursery in the future.
The panel found a number of nitriles, including cyanoallene, propargyl cyanide, cyanopropine, and possibly cyanoformaldehyde and glycolonitrile, none of which had previously been detected in the cloud known as G+0.693-0.027.
Study lead author Dr. Victor M. Rivilla, research fellow at the Center for Astrobiology at the Spanish National Research Council, said: “Here we show that the chemistry that takes place in the interstellar medium is able to efficiently form multiple nitriles, which are key molecular precursors of the ‘RNA World’ scenario.
He added: “The chemical composition of G+0.693-0.027 is similar to that of other star-forming regions in our galaxy, as well as solar system objects such as comets.
“This means that studying it could give us important information about the chemical ingredients that were available in the nebula that gave rise to our planetary system.”
The researchers used the 100-foot (30 m) wide IRAM telescope in Granada and the 130-foot (40 m) wide Yebes telescope in Guadalajara.
The panel found a number of nitriles, including cyanoallene, propargyl cyanide, and cyanopropine, that have not yet been detected in G+0.693–0.027, although they were reported in 2019 in the dark cloud TMC-1 in the constellation Taurus. and Auriga, a molecular cloud with conditions very different from G+0.693-0.027.
The scientists also found possible evidence for the presence of cyanoformaldehyde and glycolonitrile.
Cyanoformaldehyde was first detected in the molecular clouds TMC-1 and Sgr B2 in the constellation Sagittarius, and glycolonitrile was first detected in the sun-like protostar IRAS16293-2422 B in the constellation Ophiuchus.
Two types of chemical building blocks, or nucleobases, are needed to form DNA and RNA.
Study co-author Dr. Miguel A. Requena-Torres, professor at Towson University in Maryland, said: “Thanks to our observations over the past few years, including the present results, we now know that nitriles are one of the most common chemical families in the world. Universe.
“We found them in molecular clouds at the center of our galaxy, protostars of various masses, meteorites and comets, and in the atmosphere of Titan, Saturn’s largest moon.”
The author, Dr. Isacun Jiménez-Serra, also a researcher at the Center for Astrobiology at the Spanish National Research Council, said: “So far, we have discovered several simple precursors of ribonucleotides, the building blocks of RNA.
“But there are still key missing molecules that are difficult to detect.
“For example, we know that the origin of life on Earth probably also required other molecules, such as lipids, which are responsible for the formation of the first cells.
“Therefore, we should also focus on understanding how lipids can form from the simpler precursors available in the interstellar medium.”
The study is published in the journal Frontiers.
EXPLAINING DNA AND RNA: MOLECULES CONTAINING GENETIC INFORMATION FOR LIFE
DNA – deoxyribonucleic acid – is widely known as the molecule found in the nucleus of all our cells and containing genetic information.
It has the shape of a double helix and consists of small sections called nucleotides.
Each nucleotide contains a nitrogenous base, a sugar and a phosphate group.
The sugar component in this particular molecule is called deoxyribose and makes up the letter D in DNA.
It is a cyclic carbon-based chemical with five carbon atoms arranged in a pentagon.
A singular hydrogen atom is attached to the second carbon atom in deoxyribose.
Additional oxygen may also be attached to this.
In this case, the oxygenated chemical then forms what is simply known as ribose, the R in RNA.
deoxy prefix literally means without oxygen.
Shape of RNA and DNA
Ribose can do almost everything that deoxyribose can do, as well as encode genetic information in some cells and organisms.
When oxygen is present, it drastically changes how chemicals bind to and sit next to other molecules.
When oxygen is present – in RNA – it can take on a variety of forms.
When oxygen is absent from that particular location—in the DNA—the molecule forms the iconic double helix.
Use of RNA
DNA is often broken down into RNA and read by cells to translate and decipher the genetic code to make proteins and other molecules necessary for life.
RNA uses the same base pairs as DNA: cytosine, guanine, adenine.
The other base pair, thymine, has been replaced in RNA by uracil.
RNA is also commonly found in simpler organisms such as bacteria.
Often it is also a virus, in hepatitis, influenza and HIV all forms of RNA.
All animal cells use DNA, with one notable exception: mitochondria.
Mitochondria are the powerhouses of the cell and convert glucose to pyruvate and then to adenosine triphosphate (ATP) through the Krebs cycle.
This entire process takes place in this single organelle in cells, and ATP is the universal form of energy and is used in all aerobic organisms.
Mitochondria contain a small strand of RNA that is unique to the animal kingdom.
It is transmitted exclusively from the mother (the father lives in the sperm but dissolves during fertilization) and allows people to trace their maternal lineage through time.
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