Khodi ya Majini mu Cholowa cha Makhalidwe
Cholowa ndi njira yomwe makhalidwe a m'thupi amapatsidwira kuchokera kwa makolo kupita kwa ana awo. N'chifukwa chiyani mwana angakhale ndi mtundu wa maso wofanana ndi bambo ake, mtundu wa tsitsi wofanana ndi amayi ake, kapena ngakhale kukhala ndi matenda enaake? Yankho lili mu jini, "chilankhulo" cha m'thupi chomwe chimasungidwa mu DNA chomwe chimalamulira momwe zamoyo zimakulira, kukula, ndi kugwira ntchito. Ndi kudzera mu jini iyi pomwe chidziwitso cha makhalidwe chimalembedwa, kuwerengedwa, ndi kuperekedwa kuchokera ku mibadwomibadwo.
DNA ngati malo osungiramo chidziwitso cha majini
Pafupifupi selo lililonse m'thupi la munthu lili ndi nucleus yomwe imasunga DNA (deoxyribonucleic acid). DNA ingafanane ndi buku la malangizo a moyo. Kapangidwe ka DNA ndi double helix yopangidwa ndi mayunitsi ang'onoang'ono otchedwa nucleotides. Nucleotide iliyonse ili ndi imodzi mwa maziko anayi a nitrogenous: adenine (A), thymine (T), cytosine (C), ndi guanine (G). Mndandanda wa maziko anayi awa umakhala "zilembo" zomwe zimapanga chilankhulo cha majini.
Kugwirizanitsa maziko mu DNA kumakhala kokhazikika: A awiriawiri okhala ndi T, pomwe C awiriawiri okhala ndi G. Lamulo logwirizanitsa ili ndi lofunika chifukwa limalola DNA kudzikopa yokha molondola maselo akamagawikana. Njira yokopera (kubwerezabwereza) imatsimikizira kuti ana a selo amalandira malangizo ofanana a majini kuti makhalidwe oyambira asungidwe.
Majini, ma alleles, ndi ma chromosome: malangizo oyendetsera cholowa
Chidziwitso cha majini sichimagawidwa mwachisawawa, koma chimagawidwa m'magawo ogwira ntchito otchedwa majini. Majini ndi magawo a DNA omwe ali ndi malangizo opangira zinthu zinazake—nthawi zambiri mapuloteni—omwe amakhudza kapangidwe ndi ntchito ya thupi. Magulu a majini amakonzedwa mu ma chromosome, kapangidwe konga ulusi komwe kamapezeka mu selo.
Anthu ali ndi ma chromosome 46, kapena ma peya 23. Peya iliyonse imakhala ndi chromosome imodzi yochokera kwa abambo ndi imodzi yochokera kwa amayi. Ichi ndichifukwa chake munthu amakhala ndi "mitundu iwiri" ya majini ambiri. Mitundu yosiyanasiyana ya jini imatchedwa ma alleles. Mwachitsanzo, pa jini yomwe imakhudza mtundu wa maso, pakhoza kukhala ma alleles omwe nthawi zambiri amapanga utoto wambiri (maso akuda) kapena utoto wochepa (maso opepuka).
Kodi tanthauzo la majini ndi chiyani?
Ngakhale kuti DNA imasunga chidziwitso, thupi liyenerabe "kumasulira" chidziwitsocho kukhala chinthu chogwirika. Apa ndi pomwe lingaliro la code ya majini limalowa. Code ya majini ndi malamulo omwe amalumikiza dongosolo la maziko mu DNA (kapena RNA) ndi dongosolo la amino acid, zomwe zimamanga mapuloteni. Mapuloteni ndi omwe amachititsa zinthu zambiri zamoyo: kuyambira pakupanga tsitsi ndi khungu, mpaka kugwira ntchito kwa ma enzymes m'mimba, mpaka kusintha kwa mahomoni.
Pamene jini "ikuyatsidwa," DNA imasinthidwa kukhala RNA (ribonucleic acid), makamaka mRNA (messenger RNA). mRNA imanyamula uthenga wa majini kupita ku ribosomes, mafakitale a mapuloteni mkati mwa maselo. Mu ribosomes, uthenga wa mRNA umawerengedwa magawo atatu nthawi imodzi m'mayunitsi otchedwa codons. Kodoni iliyonse imayimira amino acid inayake kapena chizindikiro china chake.
Mwachitsanzo, codon AUG mu mRNA nthawi zambiri imagwira ntchito ngati codon yoyambira ndipo imapanga ma code a amino acid methionine. Palinso ma stop codon, monga UAA, UAG, ndi UGA, omwe amawonetsa kutha kwa kapangidwe ka mapuloteni. Chifukwa chake, mndandanda wa ma codon umatsimikiza mndandanda wa amino acid, womwe pamapeto pake umatsimikiza mawonekedwe ndi ntchito ya puloteni.
N’chifukwa chiyani majini ndi ofunikira pa cholowa cha makhalidwe?
Makhalidwe ooneka a chamoyo amatchedwa phenotypes, monga kutalika, mtundu wa khungu, kapena mtundu wa magazi. Ma phenotypes amapangidwa kuchokera ku mgwirizano pakati pa genotype (kuphatikiza kwa ma alleles) ndi chilengedwe. Khodi ya majini ndiye mgwirizano waukulu pakati pa genotype ndi phenotype, chifukwa imatsimikiza mapuloteni omwe amapangidwa kuchokera ku chidziwitso cha majini.
Ngati jini ikasintha maziko ake—otchedwa mutation—ndiye kuti ma codon amatha kusintha. Kusintha kwa ma codon kumatha kukhala ndi mphamvu yaying'ono, yayikulu, kapena yopanda mphamvu konse, kutengera mtundu wa mutation. Mwachitsanzo:
1. Kusintha kwa chete: kusintha kwa maziko sikusintha amino acid chifukwa ma codon angapo amatha kulemba amino acid yomweyo.
2. Kusintha kwa Missense: kusintha kwa maziko kumapanga amino acid yosiyana, kotero kuti puloteni ikhoza kusintha ntchito.
3. Kusintha kopanda pake: kusintha kwa maziko kumapangitsa kuti codon ikhale yoyima msanga kwambiri kotero kuti puloteniyo imadulidwa ndipo nthawi zambiri sigwira ntchito.
Kusintha kwa mapuloteniwa kungayambitse kusiyana kwa makhalidwe kapena kuyambitsa matenda enaake a majini.
Mapangidwe a cholowa: cholamulira, chobwerezabwereza, komanso chovuta kwambiri
Gregor Mendel adayambitsa lingaliro la cholowa kudzera mu kafukufuku wake pa nandolo. Kuchokera pamenepo, mawu akuti dominant ndi recessive adadziwika. Ma allele akuluakulu nthawi zambiri amabisa zotsatira za ma allele obwerezabwereza pa phenotype. Ngati munthu ali ndi allele imodzi yolamulira ndi allele imodzi yobwerera m'mbuyo, khalidwe lolamulira nthawi zambiri ndi lomwe limawonekera. Komabe, cholowa mwa anthu nthawi zambiri chimakhala chovuta kuposa kungolamulira-recessive.
Zina mwa zinthuzi zikuphatikizapo:
– Codominance, monga momwe zilili mu dongosolo la gulu la magazi la ABO, pomwe ma alleles A ndi B onse amatha kufotokozedwa kuti apange gulu la magazi la AB.
– Kulamulira kosakwanira, pamene heterozygous phenotype ili “pakati” (pakati) pakati pa mitundu iwiri ya homozygous phenotypes.
- Makhalidwe a Polygenic, omwe ndi makhalidwe omwe amalamulidwa ndi majini ambiri nthawi imodzi, mwachitsanzo kutalika, mtundu wa khungu, ndi kulemera.
Malamulo a majini akadali maziko a machitidwe onsewa chifukwa jini iliyonse pamapeto pake imakhudza kupangidwa kwa mapuloteni kapena kuwongolera njira zamoyo m'thupi.
Udindo wa chilengedwe pakufotokozera kwa majini
Ngakhale kuti malamulo a majini ali ndi malangizo, si malangizo onse omwe amagwiritsidwa ntchito nthawi zonse. Thupi lili ndi dongosolo lowongolera lomwe limasankha majini omwe akugwira ntchito kapena osagwira ntchito nthawi iliyonse. Mwachitsanzo, maselo a khungu ndi maselo amitsempha ali ndi DNA yofanana koma amatulutsa majini osiyanasiyana, zomwe zimapangitsa kuti ntchito zawo zikhale zosiyana.
Kuphatikiza apo, zinthu zachilengedwe monga zakudya, kukhudzidwa ndi dzuwa, kupsinjika maganizo, ndi moyo zimatha kukhudza momwe majini amagwirira ntchito. Kuphunzira kusintha kwa momwe majini amagwirira ntchito popanda kusintha DNA kumadziwika kuti epigenetics. Epigenetics ikusonyeza kuti cholowa cha makhalidwe sichimangokhudza "zilembo" za DNA, komanso momwe zilembozo "zimawerengedwa" ndikugwiritsidwa ntchito ndi maselo.
Malamulo a majini ndi thanzi
Kumvetsetsa malamulo a majini n'kofunika kwambiri pa chisamaliro chaumoyo chamakono. Matenda ambiri ali ndi gawo la majini, monga mitundu ina ya kuchepa kwa magazi m'thupi, matenda a kagayidwe kachakudya, kapena matenda enaake. Kudzera mu kusanthula kwa DNA, madokotala amatha kuzindikira kusintha kwa majini komwe kungayambitse matenda, kuwunika zoopsa, komanso kusankha chithandizo choyenera.
Kupita patsogolo kwa ukadaulo monga kusanthula DNA ndi chitukuko cha mankhwala a majini kwatsegula mwayi watsopano wopewera kapena kuchiza matenda a majini. Komabe, kugwiritsa ntchito chidziwitsochi kumadzutsanso mafunso okhudza makhalidwe abwino: momwe mungatetezere chinsinsi cha deta ya majini, kuonetsetsa kuti anthu akupeza mwayi wofanana, komanso kupewa kusankhana kutengera chidziwitso cha majini.
Mapeto
Khodi ya majini ndi dongosolo lofunikira lomwe limafotokoza momwe chidziwitso mu DNA chimasamutsidwira kukhala mapuloteni omwe amapanga ndikuwongolera moyo. Mu cholowa cha makhalidwe, khodi ya majini imagwira ntchito ngati njira yayikulu yolumikizira majini obadwa kuchokera kwa makolo ndi makhalidwe omwe amawonedwa mwa ana. Kusiyanasiyana kwa maziko, kuphatikiza kwa ma alleles, kulamulira kufotokozera kwa majini, ndi mphamvu zachilengedwe pamodzi zimapangitsa kuti pakhale kusiyana kwa makhalidwe m'zamoyo. Pomvetsetsa khodi ya majini, sitingomvetsetsa chiyambi cha makhalidwe a banja komanso timapeza chinsinsi chofunikira kwambiri pakupita patsogolo mu sayansi ya zamoyo, zamankhwala, komanso kumvetsetsa kwathu moyo wokha.
