Kodhi yeMajini muNhaka yeHunhu
Nhaka inzira iyo hunhu hwemuviri hunopfuudzwa kubva kuvabereki kuenda kuvana vavo. Sei mwana angava neruvara rwemaziso rwakafanana nababa vake, ruvara rwebvudzi rwakafanana naamai vake, kana kutove nepfungwa yezvirwere zvakasiyana? Mhinduro iri mukodhi yemajini, "mutauro" wemuviri unochengetwa muDNA unodzora kukura, kukura, uye kushanda kwezvisikwa zvipenyu. Kuburikidza nekodhi iyi yemajini, ruzivo rwehunhu rwunonyorwa, kuverengwa, uye kupfuudzwa kubva kuchizvarwa kuenda kuchizvarwa.
DNA senzvimbo yekuchengetedza ruzivo rwemajini
Sero rega rega mumuviri wemunhu rine nucleus inochengeta DNA (deoxyribonucleic acid). DNA inogona kufananidzwa nebhuku remirayiridzo yehupenyu. Maumbirwo eDNA idenderedzwa repiri rakaumbwa nemayuniti madiki anonzi nucleotides. Nucleotide yega yega ine imwe yemabhesi mana ane nitrogenous: adenine (A), thymine (T), cytosine (C), uye guanine (G). Kutevedzana kwemabhesi aya mana kunova "mavara" anoumba mutauro wemajini.
Kubatana kwemasero muDNA kwakasimba: A pairs naT, ukuwo C pairs naG. Mutemo uyu wekubatanidza wakakosha nekuti unobvumira DNA kuzvikopa nemazvo kana masero akapatsanuka. Maitiro ekukopa (kudzokorodza) anoita kuti vana vemasero vagamuchire mirairo yakafanana yemajini kuitira kuti hunhu hwepakutanga hurambe huripo.
Majini, ma alleles, uye ma chromosomes: mirayiridzo yenhaka
Ruzivo rwemajini harugoverwe zvisina tsarukano, asi rwunorongwa kuita zvikamu zvinoshanda zvinonzi majini. Majini zvikamu zveDNA zvine mirairo yekugadzira zvigadzirwa zvakananga—kazhinji mapuroteni—izvo zvinozopesvedzera chimiro nekushanda kwemuviri. Mapoka emajini akarongwa mumachromosome, maumbirwo akafanana neshinda anowanikwa munucleus yesero.
Vanhu vane machromosomes makumi mana nematanhatu, kana kuti mapeya makumi maviri nematatu. Peya imwe neimwe ine chromosome imwe yakagara nhaka kubva kuna baba uye imwe kubva kuna amai. Ndokusaka munhu aine "mavhezheni maviri" emajini akawanda. Mavhezheni akasiyana ejini anonzi maallele. Semuenzaniso, kune gene rinokanganisa ruvara rwemaziso, panogona kuva nemaallele anowanzo buritsa pigment yakawanda (maziso matema) kana pigment shoma (maziso akareruka).
Chii chinorehwa nerondedzero yemajini?
Kunyange hazvo DNA ichichengeta ruzivo, muviri uchiri kuda "kushandura" ruzivo irworwo kuita chimwe chinhu chinobatika. Apa ndipo panopinda pfungwa yekodhi yemajini. Kodhi yemajini ndiyo mitemo inobatanidza kutevedzana kwemabhesi ari muDNA (kana RNA) nekutevedzana kwemaamino acids, mabhuroko ekuvaka mapuroteni. Mapuroteni ndiwo anokonzera hunhu hwakawanda hwezvinhu zvipenyu: kubva pakuumbwa kwebvudzi neganda, kusvika pakushanda kwema enzymes ekugaya, kusvika pakugadziriswa kwemahormone.
Kana jini "ravhurwa," DNA inonyorwa kuita RNA (ribonucleic acid), kunyanya mRNA (messenger RNA). mRNA inotakura meseji yemajini kuma ribosome, maindasitiri emapuroteni ari mukati memasero. Muma ribosome, meseji ye mRNA inoverengwa mabhesi matatu panguva imwe chete muzvikamu zvinonzi ma codons. Kodhoni yega yega inomiririra amino acid chaiyo kana chiratidzo chaicho.
Semuenzaniso, codon AUG mu mRNA inowanzo shanda se codon yekutanga uye ma code e amino acid methionine. Kunewo ma stop codons, akadai seUAA, UAG, uye UGA, anoratidza kuguma kwekugadzirwa kweprotein. Saka, kutevedzana kwema codons kunosarudza kutevedzana kwema amino acid, izvo zvinozopedzisira zvasarudza chimiro uye mashandiro eprotein.
Sei kodhi yemajini ichikosha pakugara nhaka kwehunhu?
Hunhu hunoonekwa hwechisikwa hunonzi phenotypes, dzakadai sehurefu, ruvara rweganda, kana rudzi rweropa. Phenotypes dzinoumbwa kubva pakubatana pakati pe genotype (musanganiswa wealleles) nenzvimbo yakakomberedza. Genetic code ndiyo inonyanya kubatana pakati pe genotype ne phenotype, sezvo ichisarudza kuti mapuroteni api anogadzirwa kubva muruzivo rwemajini.
Kana jini rikasangana nekuchinja kwebase sequence yaro—inonzi mutation—ma codon anogona kuchinja. Kuchinja kwe codon kunogona kuva nekadiki, kakuru, kana kusatombova nemhedzisiro zvachose, zvichienderana nerudzi rwemutation. Semuenzaniso:
1. Kuchinja kwakanyarara: kuchinja kwehwaro hakuchinje amino acid nekuti ma codon akati wandei anogona kunyora amino acid imwe chete.
2. Kuchinja kweMissense: kuchinja kwebase kunoburitsa amino acid yakasiyana, kuitira kuti puroteni igone kushandura mashandiro ayo.
3. Kuchinja kusina maturo: shanduko yebase inogadzira stop codon nekukurumidza zvekuti protein inochekwa uye kazhinji haishande.
Kuchinja kwemapuroteni aya kunogona kukonzera kusiyana kwehunhu kana kukonzera mamwe mamiriro ezvinhu emajini.
Maitiro enhaka: anotonga, anodzokorora, uye akaomarara
Gregor Mendel akatanga pfungwa yenhaka kuburikidza nekutsvaga kwake nezvepizi. Kubva ipapo, mazwi ekuti dominant nerecessive akatanga kuzivikanwa. Madominant alleles anowanzo vhara mhedzisiro yerecessive alleles pa phenotype. Kana munhu aine dominant allele imwe uye recessive allele imwe, hunhu hunotonga ndihwo hunowanzoonekwa. Zvisinei, nhaka muvanhu inowanzo kuve yakaoma kupfuura kungotonga-recessive.
Zvimwe zvezvivakwa zvinosanganisira:
– Codominance, sezviri muchirongwa cheboka reropa reABO, uko maallele A neB anogona kuratidzwa kuti agadzire rudzi rweropa reAB.
– Kutonga kusina kukwana, apo heterozygous phenotype iri "pakati" (pakati) pakati pema phenotype maviri e homozygous.
- Hunhu hwePolygenic, kureva hunhu hunodzorwa nemajini akawanda panguva imwe chete, semuenzaniso kureba, ruvara rweganda, uye huremu.
Kodhi yemajini inoramba iri hwaro hwemaitiro ese aya nekuti jini rega rega rinopedzisira rakanganisa kuumbwa kwemapuroteni kana kutonga kwemaitiro ehupenyu mumuviri.
Basa renharaunda mukutaura kwekodhi yemajini
Kunyange zvazvo kodhi yemajini ine mirairo, haisi mirairo yese inoshandiswa nguva dzose. Muviri une hurongwa hwekutonga hunosarudza kuti ndeapi majini anoshanda kana kuti asingashande chero nguva. Semuenzaniso, masero eganda nemasero etsinga ane DNA imwe chete asi anoratidza majini akasiyana, zvichikonzera mabasa akasiyana.
Pamusoro pezvo, zvinhu zvakaita sekudya kunovaka muviri, kupiswa nezuva, kushushikana, uye mararamiro zvinogona kukanganisa kuratidzwa kwemajini. Kudzidza nezvekuchinja kwekugadzirwa kwemajini pasina kuchinja kutevedzana kweDNA kunozivikanwa se epigenetics. Epigenetics inoratidza kuti kugara nhaka kwehunhu hakusi kungotaura nezve "mavara" eDNA chete, asiwo kuti mavara iwayo "anoverengwa" uye anoshandiswa sei nemasero.
Kodhi yemajini nehutano
Kunzwisisa kodhi yemajini kwakakosha muhutano hwemazuva ano. Zvirwere zvakawanda zvine chikamu chemajini, zvakaita semamwe marudzi ekushaya ropa, matambudziko ekugaya chikafu, kana kuti kubatwa nezvimwe zvirwere. Kuburikidza nekuongorora DNA, vanachiremba vanogona kuona shanduko dzinogona kukonzera chirwere, kuongorora njodzi, uye kutoona kurapwa kwakakodzera.
Kufambira mberi kwetekinoroji kwakadai sekutevedzana kweDNA uye kukura kwekurapa majini kwakavhura mikana mitsva yekudzivirira kana kurapa zvirwere zvemajini. Zvisinei, kushandiswa kweruzivo urwu kunomutsawo mibvunzo yetsika: maitiro ekuchengetedza zvakavanzika zve data remajini, kuve nechokwadi chekuti kuwanikwa kwakaenzana, uye kudzivirira rusarura rwakavakirwa paruzivo rwemajini.
Mhedziso
Kodhi yemajini ndiyo sisitimu huru inotsanangura kuti ruzivo rwuri muDNA runoshandurwa sei kuita mapuroteni anoumba uye anotonga hupenyu. Mukugara nhaka yehunhu, kodhi yemajini inoshanda senzira huru inobatanidza majini akagarwa nhaka kubva kuvabereki nehunhu hunoonekwa muvana. Kusiyana muzvikamu zvekutanga, kusanganiswa kwealleles, kutonga kwekutaura kwemajini, uye pesvedzero yezvakatipoteredza pamwe chete zvinoumba kusiyana kwehunhu muzvinhu zvipenyu. Nekunzwisisa kodhi yemajini, hatingonzwisisi chete mavambo ehunhu hwemhuri asiwo tinowana kiyi yakakosha yekufambira mberi mubiology, mushonga, uye kunzwisisa kwedu hupenyu pachahwo.
