Nature's smallest factory: The Calvin cycle - Cathy Symington

Najmanja tvornica prirode: Calvinov ciklus - Cathy Symington

Prevoditelj: Irma Komljenović Recezent: Ivan Stamenković

You're facing a giant bowl

Pred tobom je ogromna zdjela

of energy packed Carbon Crunchies.

žitarica prepunih energijom.

One spoonful. Two. Three.

Jedan zalogaj. Dva. Tri.

Soon, you're powered up by the energy surge

Uskoro si pun snage

zbog energije koja dolazi iz tvog obroka.

that comes from your meal.

But how did that energy get into your bowl?

Kako se ta energija našla u tvojoj zdjeli?

Energy exists in the form of sugars

Energija postoji u obliku šećera

made by the plant your cereal came from,

kojeg rade biljke što čine tvoje žitarice,

like wheat or corn.

poput pšenice i kukuruza.

As you can see, carbon is the chemical backbone,

Kao što vidiš, ugljik je kemijski temelj,

and plants get their fix of it

a biljke svoju dozu dobivaju

in the form of carbon dioxide, CO2,

u obliku ugljikova dioksida, CO2,

from the air that we all breath.

iz zraka kojeg dišemo.

But how does a plant's energy factory,

Kako onda tvornica energije biljke,

housed in the stroma of the chloroplast,

koja se nalazi u stromi kloroplasta,

turn a one carbon gas, like CO2,

pretvori plin s jednim atomom ugljika, poput CO2,

into a six carbon solid, like glucose?

u krutinu sa šest ugljikovih atoma, poput glukoze?

If you're thinking photosynthesis, you're right.

Ako misliš na fotosintezu, u pravu si.

But photosynthesis is divided into two steps.

No fotosinteza je podijeljena u dva koraka.

The first, which stores energy from the sun

Prvi, u kojem se Sunčeva energija pohranjuje

in the form of adenosine triphosphate, or ATP.

u obliku molekule adenozin trifosfata, ili ATP-a.

And the second, the Calvin cycle, that captures carbon

I drugi, Calvinov ciklus, u kojem je ugljik uhvaćen

and turns it into sugar.

i pretvoren u šećer.

This second phase represents one of nature's

Drugi korak predstavlja jednu od

most sustainable production lines.

najodrživijih pokretnih traka prirode.

And so with that, welcome to world's most miniscule factory.

Time dolazimo do najmanje tvornice na svijetu.

The starting materials?

Početni materijali?

A mix of CO2 molecules from the air,

Kombinacija molekula CO2 iz zraka,

and preassembled molecules called

i prije nastalih molekula

ribulose biphosphate, or RuBP,

ribuloze difosfata, ili RuBP,

each containing five carbons.

od kojih svaka ima pet atoma ugljika.

The initiator? An industrious enzyme named rubisco

Pokretač? Vrijedan enzim rubisco

that welds one carbon atom from a CO2 molecule

koji vari atom ugljika iz molekule CO2

with the RuBP chain

s RuBP lancem

to build an initial six carbon sequence.

da bi izgradili primarni niz od šest atoma ugljika.

That rapidly splits into two shorter chains

On se brzo dijeli na dva kraća lanca,

containing three carbons each

tako da svaki ima tri atoma ugljika,

and called phosphoglycerates, or PGAs, for short.

koji se zovu fosfoglicerati, ili kraticom, PGA-i.

Enter ATP, and another chemical called

Sad se uključuje ATP i molekula

nicotinamide adenine dinucleotide phosphate,

nikotinamid adenin dinukleotid fosfat,

or just NADPH.

ili samo NADPH.

ATP, working like a lubricant, delivers energy,

ATP, koji djeluje kao lubrikant, oslobađa energiju

while NADPH affixes one hydrogen to each of the PGA chains,

dok NADPH dodaje atom vodika svakom lancu PGA-a,

changing them into molecules called

mijenjajući ih u molekule

glyceraldehyde 3 phosphates, or G3Ps.

gliceraldehid 3-fosfata, ili G3P-a.

Glucose needs six carbons to form,

Za stvaranje glukoze potrebno je šest atoma ugljika,

made from two molecules of G3P,

napravljenih od dvije molekule G3P-a,

which incidentally have six carbons between them.

koji slučajno međusobno imaju šest atoma ugljika.

So, sugar has just been manufactured, right?

Šećer je sad stvoren, zar ne?

Not quite.

Ne baš.

The Calvin cycle works like a sustainable production line,

Calvinov ciklus funkcionira kao održiva pokretna traka,

meaning that those original RuBPs

što znači da originalni RuBP-i

that kicked things off at the start,

koji su sve započeli,

need to be recreated by reusing materials

moraju biti stvoreni ponovnim korištenjem materijala

within the cycle now.

koji su još u ciklusu.

But each RuBP needs five carbons

Ali svaki RuBP treba pet atoma ugljika,

and manufacturing glucose takes a whole six.

a za stvaranje glukoze potrebno ih je šest.

Something doesn't add up.

Nešto nije u redu.

The answer lies in one phenomenal fact.

Odgovor leži u izvanrednoj činjenici.

While we've been focusing on this single production line,

Dok smo bili usredotočeni na jednu pokretnu traku,

five others have been happening at the same time.

pet se drugih događalo u isto vrijeme.

With six conveyor belts moving in unison,

Sa šest pokretnih traka koje se kreću u isto vrijeme,

there isn't just one carbon that gets soldered

ne lemi se samo jedan ugljik

to one RuBP chain,

na jedan RuBP lanac,

but six carbons soldered to six RuBPs.

već šest ugljika na šest RuBP-a.

That creates 12 G3P chains instead of just two,

To stvara 12 G3P lanaca, umjesto samo 2,

meaning that all together, 36 carbons exist:

što znači da sveukupno postoji 36 atoma ugljika:

the precise number needed to manufacture sugar,

i točno ih toliko treba za proizvodnju šećera

and rebuild those RuBPs.

i ponovnu izgradnju RuBP-a.

Of the 12 G3Ps pooled together,

Od 12 ujedinjenih G3P-a,

two are siphoned off to form

dva su odnesena da čine

that energy rich six carbon glucose chain.

lanac glukoze sa šest ugljika bogatog energijom.

The one fueling you via your breakfast. Success!

Onaj koji te pokreće preko tvog doručka. Uspjeh!

But back on the manufacturing line,

Vratimo se pokretnoj traci,

the byproducts of this sugar production

nusprodukti proizvodnje šećera

are swiftly assembled to recreate those six RuBPs.

brzo su sklopljeni tako da čine šest RuBP-a.

That requires 30 carbons,

Za to je potrebno 30 atoma ugljika,

the exact number contained by the remaining 10 G3PS.

a točno ih toliko i ima u ostalih 10 G3P-a.

Now a molecular mix and match occurs.

A sada će se molekule izmiješati i međusobno spajati.

Two of the G3Ps are welded together

Dva su G3P-a zavarena

forming a six carbon sequence.

i čine niz od 6 atoma ugljika.

By adding a third G3P, a nine carbon chain is built.

Dodatkom trećeg G3P-a, stvoren je lanac s 9 ugljika.

The first RuBP, made up of five carbons,

Prvi RuBP, građen od pet ugljika,

is cast from this,

maknut je odavde,

leaving four carbons behind.

ostavivši četiri atoma ugljika.

But there's no wastage here.

No ovdje nema rasipanja.

Those are soldered to a fourth G3P molecule,

Oni su zavareni, pa čine četvrtu molekulu G3P-a,

making a seven carbon chain.

tvoreći lanac sa 7 ugljika.

Added to a fifth G3P molecule,

Dodatkom pete molekule G3P-a

a ten carbon chain is created,

nastaje lanac s 10 ugljika;

enough now to craft two more RuBPs.

dovoljno za još dva RuBP-a.

With three full RuBPs recreated

S tri RuBP-a ponovno stvorenih

from five of the ten G3Ps,

s pet od deset G3P-a,

simply duplicating this process

jednostavno udvostručenje procesa

will renew the six RuBP chains

obnovit će šest lanaca RuBP-a

needed to restart the cycle again.

potrebnih za ponovno pokretanje ciklusa.

So the Calvin cycle generates the precise number

Calvinov ciklus, dakle, stvara točan broj

of elements and processes

elemenata i procesa

required to keep this biochemical production line

potrebnih za neprestano pokretanje

turning endlessly.

ove biokemijske pokretne trake.

And it's just one of the 100s of cycles

A samo je jedan u stotinama ciklusa

present in nature.

prisutnih u prirodi.

Why so many?

Zašto tako puno?

Because if biological production processes were linear,

Jer, da biološki procesi proizvodnje nisu linearni,

they wouldn't be nearly as efficient or successful

ne bi bili ni približno učinkoviti i uspješni

at using energy to manufacture the materials

u korištenju energije za proizvodnju materijala

that nature relies upon, like sugar.

o kojima priroda ovisi, poput šećera.

Cycles create vital feedback loops

Ciklusi stvaraju bitne petlje

that repeatedly reuse and rebuild ingredients

koje neprestano ponovno koriste i izgrađuju sastojke,

crafting as much as possible

stvarajući što je više moguće

out of the planet's available resources.

iz dostupnih resursa Zemlje.

Such as that sugar,

Poput onog šećera,

built using raw sunlight and carbon

izgrađenog pomoću Sunčeve svjetlosti i ugljika

converted in plant factories

pretvorenih u biljnim tvornicama

to become the energy that powers you

u energiju koja ti daje snagu

and keeps the cycles revolving in your own life.

i održava kretnju ciklusa u tvom životu.