The genes you don't get from your parents (but can't live without) - Devin Shuman

Prevodilac: Milena Petrovic Lektor: Milenka Okuka

Inside our cells, each of us has a second set of genes

Unutar naših ćelija, svako od nas ima drugi skup gena

completely separate from the 23 pairs of chromosomes

u potpunosti odvojenih od 23 para hromozoma

we inherit from our parents.

koje nasleđujemo od roditelja.

And this isn’t just the case for humans—

Ovo nije samo slučaj kod ljudi—

it’s true of every animal, plant, and fungus,

već i kod svake životinje, biljke, gljive,

and nearly every multicellular organism on Earth.

i približno svakog višećelijskog organizma na zemlji.

This second genome belongs to our mitochondria,

Ovaj drugi genom pripada našim mitohondrijama,

an organelle inside our cells.

tj. organelama unutar naših ćelija.

They’re not fully a part of us, but they’re not separate either—

One nisu u potpunosti deo nas, ali nisu ni odvojene—

so why are they so different from anything else in our bodies?

zbog čega su one toliko različite od svega ostalog u našim telima?

Approximately 1.5 billion years ago,

Otprilike pre oko 1,5 milijardi godina,

scientists think a single-celled organism engulfed the mitochondria’s ancestor,

naučnici misle da je jednoćelijski organizam progutao pretka mitohondrije,

creating the predecessor of all multicellular organisms.

stvarajući prethodnika svih višećelijskih organizama.

Mitochondria play an essential role:

Mitohondrije igraju važnu ulogu:

they convert energy from the food we eat and oxygen we breathe

one pretvaraju energiju iz hrane i kiseonika koji dišemo

into a form of energy our cells can use, which is a molecule called ATP.

u vid energije koju naše ćelije koriste, a to je molekul koji se zove ATP.

Without this energy, our cells start to die.

Bez ove energije, naše ćelije počinju da odumiru.

Humans have over 200 types of cells,

Ljudi imaju preko 200 vrsta ovih ćelija,

and all except mature red blood cells have mitochondria.

i sve, osim zrelih crvenih krvnih zrnaca, imaju mitohondrije.

That’s because a red blood cell’s job is to transport oxygen,

To je zato što je posao crvenih krvnih zrnaca prenos kiseonika,

which mitochondria would use up before it could reach its destination.

koji bi mitohondrije iskoristile pre nego što stignu do svog odredišta.

So all mitochondria use oxygen and metabolites to create energy

Znači, sve mitohondrije koriste kiseonik i metabolite da stvore energiju

and have their own DNA,

i imaju svoju DNK,

but mitochondrial DNA varies more across species than other DNA.

ali DNK mitohondrije više varira među vrstama od druge DNK.

In mammals, mitochondria usually have 37 genes.

Kod sisara, mitohondrije obično imaju 37 gena.

In some plants, like cucumbers, mitochondria have up to 65 genes,

Kod nekih biljaka, kao što su krastavci, mitohondrije imaju i do 65 gena,

and some fungal mitochondria have only 1.

a neke mitohondrije gljiva imaju samo jedan.

A few microbes that live in oxygen-poor environments

Nekoliko mikroba koji žive u sredinama osiromašenim kiseonikom

seem to be on the way to losing their mitochondria entirely,

izgleda da su na putu da izgube svoje mitohondrije u potpunosti,

and one group, oxymonad monocercomonoides, already has.

a jedna grupa, oxymonad monocercomonoides, ih je već izgubila.

This variety exists because mitochondria are still evolving,

Ova raznolikost postoji zato što mitohondrije još uvek evoluiraju,

both in tandem with the organisms that contain them,

zajedno sa organizmima koji ih sadrže,

and separately, on their own timeline.

kao i odvojeno, u svoje vreme.

To understand how that’s possible,

Da bismo shvatili kako je to moguće,

it helps to take a closer look at what the mitochondria inside us are doing,

pomoći će nam ako bliže pogledamo šta mitohondrije unutar nas rade,

starting from the moment we’re conceived.

počevši od trenutka kada smo začeti.

In almost all species, mitochondrial DNA is passed down from only one parent.

Kod većine vrsta, mitohondrijalna DNK se dobija od samo jednog roditelja.

In humans and most animals, that parent is the mother.

Kod ljudi i većine životinja, taj roditelj je majka.

Sperm contain approximately 50 to 75 mitochondria in the tail,

Sperma sadrži oko 50 do 75 mitohondrija u repu,

to help them swim.

kao pomoć pri plivanju.

These dissolve with the tail after conception.

One se rastvore zajedno sa repom nakon začeća.

Meanwhile, an egg contains thousands of mitochondria,

U međuvremenu, jajašce sadrži hiljadu mitohondrija,

each containing multiple copies of the mitochondrial DNA.

gde svaka sadrži više primeraka mitohondrijalne DNK.

This translates to over 150,000 copies of mitochondrial DNA

Ovo se prevodi u preko 150 000 primeraka mitohondrijalne DNK

that we inherit from our mothers,

koju nasleđujemo od svojih majki,

each of which is independent and could vary slightly from the others.

od kojih je svaki nezavisan i može neznatno da varira od drugih.

As a fertilized egg grows and divides,

Kako oplođeno jajašce raste i počinje da se deli,

those thousands of mitochondria are divvied up into the cells

tih hiljadu mitohondrija se dele na ćelije

of the developing embryo.

embriona koji se razvija.

By the time we have differentiated tissues and organs,

Do trenutka kada se tkiva i organi počnu razlikovati,

variations in the mitochondrial DNA are scattered at random throughout our bodies.

varijacije mitohondrijalne DNK su već nasumično razbacane po telu.

To make matters even more complex,

Da stvar bude složenija,

mitochondria have a separate replication process from our cells.

mitohondrije imaju zaseban proces replikacije od naših ćelija.

So as our cells replicate by dividing, mitochondria end up in new cells,

Kako se naše ćelije replikuju deobom, mitohondrije završe u novim ćelijama,

and all the while they’re fusing and dividing themselves,

dok se i same spajaju i dele,

on their own timeline.

u svoje vreme.

As mitochondria combine and separate,

Kako se mitohondrije spajaju i razdvajaju,

they sequester faulty DNA or mitochondria that aren’t working properly for removal.

one otklanjaju neispravnu DNK ili mitohondrije koje ne funkcionišu dobro.

All this means that the random selection of your mother’s mitochondrial DNA

Ovo znači da nasumična selekcija mitohondrijalne DNK majke

you inherit at birth

koju nasleđujete po rođenju

can change throughout your life and throughout your body.

može da se menja tokom života kao i duž tela.

So mitochondria are dynamic and, to a degree, independent,

Znači, mitohondrije su dinamične i, u nekoj meri, nezavisne,

but they’re also shaped by their environments: us.

ali ih isto tako oblikuje i sredina: mi.

We think that long ago,

Mislimo da su veoma davno,

some of their genes were transferred to their host’s genomes.

neki od njihovih gena premešteni u genome njihovog domaćina.

So today, although mitochondria have their own genome

Ali danas, iako mitohondrije imaju sopstveni genom

and replicate separately from the cells that contain them,

i replikuju se zasebno od ćelija koje ih sadrže,

they can't do this without instruction from our DNA.

one ovo ne mogu da urade bez instrukcija naše DNK.

And though mitochondrial DNA is inherited from one parent,

I iako se mitohondrijalna DNK nasleđuje od jednog roditelja,

the genes involved in building and regulating the mitochondria

geni koji učestvuju u građenju i regulisanju mitohondrija

come from both.

potiču od oboje.

Mitochondria continue to defy tidy classification.

Mitohondrije nastavljaju da prkose urednoj klasifikaciji.

Their story is still unfolding inside of each of our cells,

Njihova priča se još uvek odvija unutar svake naše ćelije,

simultaneously separate and inseparable from our own.

istovremeno bivajući odvojeni i neodvojivi deo naših ćelija.

Learning more about them can both give us tools

Učeći više o njima nam može dati alate

to protect human health in the future, and teach us more about our history.

da zaštitimo zdravlje ljudi u budućnosti, kao i da naučimo više o našoj istoriji.