Some of the building blocks of life, known as nitriles, have been detected by scientists in the heart of our galaxy, the Milky Way.
They were discovered in a molecular cloud of gas and dust by a team of international researchers using two telescopes in Spain.
Nitriles are important building blocks for RNA, a DNA-like nucleic acid present in all living cells.
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 on RNA alone, with DNA and protein enzymes evolving later.
RNA can fulfill both functions: store and copy information like DNA and catalyze reactions like enzymes.
According to the ‘RNA World’ theory, nitriles and other building blocks for life need not have arisen on Earth itself.
Discovery: Scientists have detected some of the key building blocks of life, known as nitriles, at the heart of our galaxy, the Milky Way. They were seen in a molecular cloud of gas and dust (similar to this one in the photo) by a team of international researchers.
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 the nitriles could have originated in space and “hitch-hiked” to the young Earth inside meteorites and comets (stock image)
LIFE ON EARTH MAY HAVE STARTED THANKS TO A MODIFIED VERSION OF MODERN RNA
Life on Earth may have started thanks to a modified version of the sister molecule of modern DNA, scientists believe.
DNA is the backbone of life and almost everything on our planet depends on it, but on primordial Earth, a primitive version of its lesser-known sibling, RNA, was the focal point of evolution, experts say.
RNA is structurally similar to DNA, except that one of the four building blocks, thymine, is replaced with uracil.
This changes the shape and structure of the molecule, and researchers have long believed that this chemical was vital to the development of Earth’s first life forms.
An accidental discovery by Harvard academics published in December 2018 found that a slightly different version of RNA could have been the key ingredient that allowed life to flourish on Earth.
Scientists say that a chemical called inosine may have been present in place of guanine, allowing life to develop.
This slight change in bases, known as nucleotides, may provide the first known proof of the ‘RNA world hypothesis’, a theory that claims RNA was integral to early life forms, they say.
They could also have originated in space and ‘hitchhiked’ to the young Earth inside meteorites and comets during the ‘Late Heavy Bombardment’ period, between 4.1 and 3.8 billion years ago.
In support, nitriles and other nucleotide, lipid, and amino acid precursor molecules have been found within recent comets and meteorites.
The question is, where in space could these molecules have come from?
The main candidates are molecular clouds, which are cold, dense 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 around 100 K and is about three light-years across, with a mass 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 that it could evolve to become a stellar nursery in the future.
The team of experts detected a variety of nitriles including cyanoallene, propargyl cyanide, cyanopropyne, and possibly cyanoformaldehyde and glyconitrile, none of which had previously been found in the cloud, which is known as G+0.693-0.027.
Lead author of the study, Dr Víctor M. Rivilla, a researcher at the Center for Astrobiology of the Higher Council for Scientific Research in Spain, said: “Here we show that the chemistry that takes place in the interstellar medium is capable of efficiently forming multiple nitriles, which are key molecular precursors of the “RNA World” scenario.
He added: ‘The chemical content of G+ 0.693-0.027 is similar to that of other star-forming regions in our galaxy, and also to that of solar system objects such as comets.
“This means that their study can give us important information about the chemical ingredients that were available in the nebula that give rise to our planetary system.”
The researchers used the 30 m (100 ft) wide IRAM Granada telescope and the 40 m (130 ft) wide Yebes telescope in Guadalajara.
The team of experts detected a variety of nitriles, including cyanoallene, propargyl cyanide and cyanopropyne, which had not yet been found at G+ 0.693-0.027, although they had been reported in 2019 in the dark cloud TMC-1 in the constellations of Taurus. . and Auriga, a molecular cloud with very different conditions at G + 0.693-0.027.
The scientists also found possible evidence of cyanoformaldehyde and glycolonitrile.
Cyanoformaldehyde was first detected in the molecular clouds TMC-1 and Sgr B2 in the constellation Sagittarius, and glyconitrile in the Sun-like protostar IRAS16293-2422 B in the constellation Ophiuchus.
Two types of chemical building blocks, or nitrogenous bases, are needed for DNA and RNA to form.
Study author Dr. Miguel A Requena-Torres, a professor at Towson University in Maryland, said: “Thanks to our observations over the last few years, including the current results, we now know that nitriles are among the families most abundant chemicals in the universe.
“We have found them in molecular clouds in the center of our galaxy, protostars of different masses, meteorites and comets, and also in the atmosphere of Titan, Saturn’s largest moon.”
Author Dr Izaskun Jiménez-Serra, also a researcher at the Center for Astrobiology of Spain’s Higher Council for Scientific Research, said: “So far, we have detected several simple precursors of ribonucleotides, the building blocks of RNA.”
“But key molecules that are difficult to detect are still missing.
‘For example, we know that the origin of life on Earth probably also required other molecules such as lipids, responsible for the formation of the first cells.
“So we should also focus on understanding how lipids can be formed from simpler precursors available in the interstellar medium.”
The study has been published in the journal borders.
DNA AND RNA EXPLAINED: THE MOLECULES THAT CONTAIN THE GENETIC INFORMATION FOR LIFE
DNA – deoxyribonucleic acid – is widely known as the molecule found in the nucleus of all our cells, containing genetic information.
It is shaped like a double helix and is made up of small sections called nucleotides.
Each nucleotide contains a nucleobase, a sugar, and a phosphate group.
The sugar component in this particular molecule is called deoxyribose and it forms the D in DNA.
This is a cyclic carbon based chemical with five carbon atoms arranged like a pentagon.
On the second carbon atom there is a single attached hydrogen atom in deoxyribose.
This can also have an additional oxygen attached to it as well.
In this case, the oxygenated chemical forms what is known simply as ribose, the R in RNA.
the deoxyribonucleic prefix literally means without oxygen.
Form of RNA and DNA
RIbose can do almost everything that deoxyribose can and also encodes genetic information in some cells and organisms.
When oxygen is present, it drastically alters the way chemicals bind and sit next to other molecules.
When oxygen is present, in RNA, it can take a variety of forms.
When oxygen is not present at this specific location, in DNA, the molecule forms as the iconic double helix.
DNA is often broken down into RNA and read by cells to translate and transcribe the genetic code to make proteins and other molecules essential for life.
RNA uses three of the same base pairs as DNA: cytosine, guanine, and adenine.
The second base pair, Thymine, is exchanged in the RNA for Uracil.
RNA is also often found in simpler organisms, such as bacteria.
It is also often a virus, with hepatitis, influenza and HIV all forms of RNA.
All animal cells use DNA, with one notable exception: the mitochondria.
Mitochondria are the powerhouses of the cell and convert glucose to pyruvate and then to adenosine triphosphate (ATP) through the Krebs cycle.
All this process is done in this organelle in the cells and ATP is the universal form of energy and is used in all aerobic organisms.
In the mitochondria there is a short strand of RNA that is unique in the animal kingdom.
It is transmitted exclusively from the mother (the father lives in the sperm but dissolves during fertilization) and allows humans to trace their maternal lineage through time.
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