Some of the main building blocks of life – known as nitriles – have been detected by scientists in the heart of our galaxy, the Milky Way.
They were spotted in a molecular cloud of gas and dust by a team of international researchers using two telescopes in Spain.
Nitriles are important building blocks of RNA – a DNA-like nucleic acid found 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 solely on RNA, and that DNA and protein enzymes evolved later.
RNA can perform both of their functions: storing and copying information like DNA, and catalyzing reactions like enzymes.
According to the RNA World theory, nitriles and other building blocks of life need not all have originated on Earth itself.
Discovery: Some of the main building blocks of life, known as nitriles, have been detected by scientists in the heart of our galaxy, the Milky Way. They were spotted in a molecular cloud of gas and dust (similar to this one) 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 nitriles could come from space and ‘hitchhike’ to young Earth inside meteorites and comets (stock image)
LIFE ON EARTH MAY HAVE STARTED FROM AN MODIFIED VERSION OF MODERN RNA
Scientists say life on Earth may have started with a modified version of the sister molecule to modern DNA.
DNA is the backbone of life and almost our entire planet depends on it but, on primordial Earth, an early version of its lesser-known sister – 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 substituted for uracil.
This changes the shape and structure of the molecule and researchers have long believed that this chemical was vital for the development of early life forms on Earth.
An accidental discovery by Harvard scholars published in December 2018 revealed that a slightly different version of RNA may have been the key ingredient allowing life on Earth to flourish.
Scientists claim 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, could provide the first known evidence for the ‘RNA world hypothesis’ – a theory that claims RNA was an integral part of early life forms – say -they.
They could also have originated in space and ‘hitchhiked’ to young Earth inside meteorites and comets during the ‘late heavy bombardment’ period between 4 .1 and 3.8 billion years.
In support, nitriles and other nucleotide, lipid and amino acid precursor molecules have been found inside recent comets and meteors.
The question is, where could these molecules come from in space?
The main candidates are molecular clouds, which are dense and cold regions of the interstellar medium, and 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 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 inside G+0.693-0.027, although scientists suspect it may evolve into a stellar nursery in the future.
The expert team detected a range of nitriles including cyanoallene, propargyl cyanide, cyanopropyne and possibly cyanoformaldehyde and glycolonitrile, none of which had previously been found in the cloud, known as G+ 0.693-0.027.
The study’s lead author, Dr. Víctor M. Rivilla, a researcher at the Center for Astrobiology of Spain’s National Research Council, said: “Here we show that the chemistry that occurs in the interstellar medium is capable to effectively form several nitriles, which are essential. molecular precursors to 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, as well as that of solar system objects like comets.
“This means that his study can give us important information about the chemical ingredients that were available in the nebula and 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 expert team detected a range of nitriles including cyanoallene, propargyl cyanide and cyanopropyne, which had not previously been found in G+0.693-0.027, although they were reported in 2019 in the black cloud TMC-1 in the constellations of Taurus. and Auriga, a molecular cloud with conditions very different from G+0.693-0.027.
Scientists have also found possible evidence of cyanoformaldehyde and glycolonitrile.
Cyanoformaldehyde was first detected in molecular clouds TMC-1 and Sgr B2 in the constellation Sagittarius, and glycolonitrile in the sun-like protostar IRAS16293-2422 B in the constellation Ophiuchus.
For DNA and RNA to form, two types of chemical building blocks – or nucleobases – are needed
Study author Dr Miguel A Requena-Torres, a senior lecturer at the University of Towson in Maryland, said: “From our observations over the past several years, including the current results, we know now that nitriles are among the most abundant chemical families in the world. universe.
“We have found them in molecular clouds at the center of our galaxy, protostars of varying masses, meteorites and comets, and in the atmosphere of Titan, Saturn’s largest moon.”
Author Dr Izaskun Jiménez-Serra, also a researcher at the Spanish National Research Council’s Center for Astrobiology, said: ‘We have so far detected several simple precursors of ribonucleotides, the building blocks of RNA .
“But there are still key molecules missing that are difficult to detect.
“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.
“Therefore, we should also focus on understanding how lipids might be formed from simpler precursors available in the interstellar medium.”
The study was published in the journal Frontiers.
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 that contains 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 of this particular molecule is called deoxyribose and is the D in DNA.
It is a cyclic carbon-based chemical with five carbon atoms arranged in a pentagon.
At the second carbon atom, there is a singular hydrogen atom attached in deoxyribose.
This may also have additional oxygen attached as well.
In this case, the oxygenated chemical then forms what is simply called ribose – the R in RNA.
The deoxy prefix literally means without oxygen.
Shape of RNA and DNA
RIbose can do almost everything deoxyribose can do and also encodes genetic information in some cells and organisms.
When oxygen is present, it drastically changes the way chemicals bind and mix with other molecules.
When oxygen is present – in RNA – it can take various forms.
When oxygen is not present at that specific location – in DNA – the molecule forms as the iconic double helix.
Uses of RNA
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, adenine.
The other base pair, thymine, is exchanged in RNA for uracil.
RNA is also often found in simpler organisms, such as bacteria.
It is often also a virus, with 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 into pyruvate and then into adenosine triphosphate (ATP) via the Krebs cycle.
This process is done entirely in this organelle in the cells and ATP is the universal form of energy and is used in any aerobic organism.
Within the mitochondria there is a small strand of RNA which is unique in the animal kingdom.
It is transmitted exclusively by 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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