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We believe of atomic number 8 as aliveness , sustenance , a literal breath of fresh atmosphere . But it ’s actually a very reactive element . Anyone who’sburned a loghas witnessed this firsthand . So why do so many life - forms breathe O ?
There are probably thousands of kinds of metabolic process , or chemical substance processes that maintain life , saidDonald Canfield , a geobiologist at the University of Southern Denmark , but " virtually all eukaryotes " ( life - course whose cells contain a nucleus ) and a vast regalia ofprokaryotes(life - forms that lack a nucleus ) , use oxygen .
Oxygen is a very reactive element, so why do so many lifeforms breathe it?
Canfield is talking in the first place about heterotroph — being , including humanity , that get their nutrients and energy by down other constitutive matter . Not all organisms do this alone . For example , " plants get their atomic number 6 from CO2 in the melody , " saidDan Mills , a postdoctoral research worker at the University of Munich .
Heterotrophs break down organic matter in food for thought by stripping electrons off of it . These are passed from one enzyme to another in the membrane of the mitochondria , generating a small-scale flow that pump protons across this barrier . And given its high electronegativity , O usually serves as the last place on thiselectron transport range , accepting the electrons and picking up two proton to form water .
The process essentially creates a reservoir of protons that then inundate through a protein communication channel in the membrane like a tiny hydroelectric dkm . And , like a turbine , the protein synthesise DOE in the form of adenosine triphosphate ( ATP ) as it spins , explainedNick Lane , a professor of evolutionary biochemistry at University College London , in apublic presentment . The prison cell can then expend this packaged muscularity or post it off into the body to do thing .
Oxygen is a very reactive element, so why do so many lifeforms breathe it?
life sentence can use manyother electron acceptors — like sulfate , nitrate and iron — but oxygen is the highest - energy acceptor available .
" The reducing of atomic number 8 bring home the bacon the big free energy release per negatron transferral , except for the reducing of F and chlorine , " University of Washington professorDavid Catlingand his co - author explain in apaperpublished in the journalAstrobiology .
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atomic number 17 and oxygen can generate similar amounts of energy . Fluorine could sure enough supply more energy than oxygen , but " atomic number 9 is [ … ] useless as a biological oxidant because it generates an plosion upon contact with constitutional affair , " they compose in the report . That ’s not a gas you ’d want to breathe .
Chlorine and fluorine are also poisonous , which spotlight another benefit of oxygen . Aerobic respiration does n’t produce any toxic compounds , just water and carbon dioxide . However , O ’s reactivity can be an issue if it builds up in tissues , where it can damage cellular part like desoxyribonucleic acid and protein . That ’s whyantioxidants , in moderation , are good for our wellness .
Oxygen is also far more abundant than fluorine , chlorine or the uncounted electron acceptor used in other forms of ventilation . Despite its propensity for take form chemical compound with other speck , a copious amount of atomic number 8 is always produce viaphotosynthesis . This enable it to accumulate in the atmosphere and fade out in piss , where it is pronto available to life . And , as a throttle , it ’s easy to transport across tissue layer , Canfield and Mills explain .
speak of abundance , why not utilize N , which consist 78 % of Earth ’s atmosphere ?
" The main problem with atomic number 7 is that it ’s triple bonded , " Canfield said . " And it ’s very , very difficult to unwrap . "
Nitrogen is an authoritative component of many biologic chemical compound , and there are whole mathematical group of organisms that specialize in the energy - intensive processes required to go against nitrogen ’s strong bonds to make it bioavailable , Canfield pronounce .
Oxygen ’s alone utility program comes down toquantum physics . Oxygen in its normal ground res publica can only accept negatron in the same spin body politic , not as an electron pair , which is the usual currentness ofchemistry .
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" So the real john to O is that it can collect to high levels without reacting , but releases a lot of free energy ( to pump protons ) when it is feed electrons one at a clip , " Lane told Live Science in an email .
So it seems atomic number 8 sits in a sweet spot of responsiveness and handiness . It ’s milder thanhalogenssuch as atomic number 17 and F , and it is n’t bound too strongly , like N . But it ’s much more responsive than other electron acceptors , like sulfate and nitrate .
Oxygen is well-off to adopt , and it does n’t father toxic compounds that necessitate further processing . What ’s more , plants grow copious amount of money of this reactive petrol through photosynthesis , enabling us to apply it to fuel our own bodies .
Periodic table of elements quiz: How many elements can you name in 10 minutes?
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