Important precursors for life on Earth abound in the interstellar molecular clouds and can reach Earth through comets and meteors.
Nitriles, a class of living molecules with a group of cyano (a carbon atom bound to a triple bond that is not filled with a nitrogen atom), are generally toxic. Ironically, however, they also form the primary precursor to life-sustaining cells on Earth, such as ribonucleotides, composed of nucleobases or ‘letters’ A, U, C, and G, bound by a group of ribose and phosphate, which combine to form RNA. . Now, a team of scientists from Spain, Japan, Chile, Italy, and the United States is showing that a wide range of nitriles occurs in the starry heavens within the molecular cloud G + 0.693-0.027, located near the center of the Milky Way, Galaxy.
“Here we show that the chemical reaction that occurs in the galaxy is capable of producing many nitriles, which can precede the major molecular markers of ‘RNA World’,” says Drs. Víctor M. Rivilla, a researcher at the Astrobiology Institute of the Spanish National Research Council (CSIC) and the National Institute of Aerospace Technology (INTA) in Madrid, Spain, and the first author of a new study.
Possible world for ‘RNA only.’
In this context, life on Earth was initially based solely on RNA, and protein and DNA enzymes emerged later. RNA can perform both functions: stimulating reactions as enzymes and storing and copying DNA-like information. According to RNA World theory, nitriles and other life-forms have not originated on Earth itself: they may also have originated in space and ‘climbed’ on the small Earth within comets and meteorites during the ‘Later Difficulty. The time of the bombing was between 4.1 and 3.8 billion years ago. In support, nitriles and other molecules precede nucleotides, lipids, and amino acids within meteors and comets.
Where did these molecules come from? Prime candidates are molecular clouds, dense and cold regions of the interstellar medium, and are suitable for forming complex molecules. For example, the molecular cloud G + 0.693-0.027 has a temperature of about 100 K, is about three light-years wide, and is a thousand times heavier than our Sun. Although scientists suspect it may evolve into an astronomical observatory in the future, there is no evidence that the stars are currently building within G + 0.693-0.027.
“The chemical composition of G + 0.693-0.027 is similar to that of other galaxies in our galaxy, as well as those of the solar system such as comets. This means that its research can provide us with valuable insights into the chemical elements found in the nebula that make up our planetary system,” explains Rivilla.
Vitu muhimu vinavyowezesha uhai duniani viko katika mawingu ya molekuli ya kati ya nyota na vinaweza kufika Duniani kupitia nyota za nyota na nyota za mwangaza. Nitriles ni aina ya molekuli ya hai na kundi la cyano (atomu ya kaboni iliyounganishwa na kiungo cha tatu ambacho hakijazishwa na atomu ya nitrojeni), kwa ujumla ni sumu. "Kwa kushangaza, hata hivyo, wao pia huunda kiambishi cha msingi cha seli za kuendeleza maisha duniani, kama vile ribonucleotides, iliyoundwa na nucleobases au ""habari"" A, U, C, na G, iliyounganishwa na kundi la ribose na phosphate, ambayo huungana kuunda RNA." . Sasa, timu ya wanasayansi kutoka Uhispania, Japan, Chile, Italia na Marekani inaonyesha kwamba nitriles mbalimbali hutokea katika anga nyota ndani ya wingu molekuli G + 0.693 - 0.027, iko karibu na kituo cha Milky Way. "Hapa tunaonyesha kwamba athari ya kemikali ambayo hutokea katika galaxy ni uwezo wa kuzalisha nitriles wengi, ambayo inaweza kabla ya alama kuu za molekuli ya ""RNA World""", anasema Drs. Víctor M. Rivilla, mtafiti katika Taasisi ya Astrobiolojia ya Baraza la Kitaifa la Utafiti la Uhispania (CSIC) na Taasisi ya Kitaifa ya Teknolojia ya Anga (INTA) huko Madrid, Uhispania, na mwandishi wa kwanza wa utafiti mpya. Ulimwengu unaowezekana kwa <unk>RNA tu.<unk> Katika muktadha huu, maisha duniani mwanzoni yalitegemea RNA tu, na protini na enzymes za DNA zilitokea baadaye. RNA inaweza kufanya kazi zote mbili: kuchochea athari kama enzymes na kuhifadhi na kunakili habari kama DNA. Kulingana na nadharia ya Dunia ya RNA, nitriles na aina nyingine za maisha hazikutoka duniani yenyewe: zinaweza pia kutokea katika nafasi na "kupanda" kwenye Dunia ndogo ndani ya kometi na meteoriti wakati wa Ugumu wa Baadaye. Wakati wa mlipuko huo ulikuwa kati ya miaka bilioni 4.1-3.8 iliyopita. Kwa kuunga mkono hilo, nitrili na molekuli nyinginezo hufuata kabla ya nukleotidi, lipidi, na asidi za amino ndani ya nyota na kometi. Molekuli hizo zilitoka wapi? Wagombea wakuu ni mawingu ya molekuli, maeneo yenye unene na baridi ya kati ya nyota, na yanafaa kwa kuunda molekuli tata. Kwa mfano, wingu la molekuli G + 0.693 - 0.027 lina joto la karibu 100 K, lina upana wa miaka mitatu ya mwanga, na ni nzito mara elfu moja kuliko Jua letu. Ingawa wanasayansi wanashuku inaweza kubadilika kuwa kituo cha uchunguzi wa nyota katika siku zijazo, hakuna ushahidi kwamba nyota zinajengwa ndani ya G + 0.693 - 0.027. Muundo wa kemikali ya G + 0.693 - 0.027 ni sawa na ile ya galaxies nyingine katika galaxy yetu, kama vile wale wa mfumo wa jua kama vile comets. Hii inamaanisha kwamba utafiti wake unaweza kutupa ufahamu muhimu juu ya elementi za kemikali zinazopatikana katika nebula ambazo huunda mfumo wetu wa sayari, <unk> anaelezea Rivilla.