Ba tarkibi hujayra taqriban 70 elementi khimiyavii Sistemai davrii elementhoi D.I.Mendeleev dokhil meshavand, ki onho dar tabiati gayrizinda niz duchor meoyand. In yake az dalelhoi yagonagii tabiati zinda va gayrizinda ast. Lekin tanosubi elementhoi khimiyavi va ahamiyati onho dar ofaridani moddahoi tashkilkunandai organizmi zinda, hamchunin, dar har kadom obekti tabiati gayrizinda tafovvut dorand.
Olimon va tadqiqotchiyon dar borai khususiyathoi khosi tashkilyobii khimiyavii organizmhoi zinda az zamonhoi pesh malumot dodani meshudand. Botadrij dar borai tarkibi khimiyavii hujayra malumoti ilmi ba vujud omad. Vobasta ba miqdori elementhoi khimiyavii tarkibi moddaho, ki organizmi zindaro tashkil medihand, chand guruh atomho judo karda shudaast. Guruhi yakum (qarib 98%-i massai hujayra)-ro chor element: gidrogen, oksigen, karbon va nitrogen ba vujud meorand. Onho makroelementho nomida meshavand.
Qismhoi asosii tarkibii hamai payvastagihoi organiki az hamin elementho iboratand. Guruhi duyumro dar yakjoyagi du elementi khimiyavi–sulfur va fosfor tashkil menamoyand, ki qismi zarurii tarkibii molekulai polimerhoi biologi (az yunoni, polys-bisyor; meros-qism) – safedaho va kislotahoi nukleinat meboshand; onhoro bioelementho menomand.
Ba tarkibi hujayra(Kletka ba russi) gayr az fosfor va sulfur, boz ba miqdori kam shash elementi digar: kaliy, natriy, kalsiy, magniy, ohan va khlor dokhil meshavand. Har yake az onho dar hujayra vazifai muhimro ijro menamoyand. Masalan, natriy, kaliy va khlor qobiliyati guzaronandagii membranai hujayraro baroi moddahoi gunogun va guzaronidani impulshoro ba nakhhoi asab tamin mesozand. Kalsiy va fosfor dar tashkili moddai baynihujayravii boftahoi ustukhon ishtirok mekunand. Ba gayr az in, kalsiy yake az omilhoest, ki az on lakhtabandii mutadili khun vobastagi dorad. Ohan ba tarkibi gemoglobin-safedai eritrosithoi khun dokhil ast.
On dar guzaronidani oksigen az shush ba boftaho ishtirok menamoyad. Magniy boshad, dar hujayrai rastani ba tarkibi khlorofill-pigmenti sabz, ki sababi fotosintez megardad, dokhil meshavad. Dar hayvonot magniy dar tarkibi katalizatorhoi biologi-fermentho, ki dar tabadduloti biokhimiyavi ishtirok menamoyand, vujud dorad.
Hamai elementhoi boqimonda (ruh, mis, yod, ftor va gayra) – guruhi seyumro tashkil namuda, dar hujayra ba miqdori khele kam mavjudand. Hissai umumii onho 0,02%-i massai hujayraro tashkil mekunad. Binobar in, onhoro mikroelementho nomidaand. Ammo in chunin mano nadorad, ki mikroelementho baroi organizm ahamiyati kam dorand.
Mikroelementho niz baroi organizmi zinda nihoyat muhimmand, vale ba tarkibi on khele kam dokhil meshavand. Masalan, ruh ba tarkibi molekulai gormoni gadudi zeri medainsulin dokhil shuda, dar tanzimi mubodilai angishtobhoishtirok menamoyad. Yod-qismi tarkibii zarurii tiroksingormoni gadudi siparshakl buda, surati mubodilai moddahoi hamai organizmro dar shakli tom va numui onro darravandi inkishof idora menamoyad.
Hamai elementhoi khimiyavii nomburda, dar bunyod namudani organizm ba shakli ionho yo ba tarkibi in yo on payvastagiho–molekulai moddahoi gayriorganiki va organiki ishtirok mekunand.