Kumvetsa Kusiyanasiyana kwa Alleles
Ngati mwakhala mukuwerenga za chikhalidwe cha chibadwa, mwina mwapeza mawu akuti "homozygous" kapena "heterozygous"? Koma kodi mawu awa akutanthauza chiyani? Ndipo ndi zotsatira zotani zokhudzana ndi "homozygous" kapena "heterozygous" pa jini yeniyeni?
Gene Ndi Chiyani?
Asananene za homozygous ndi heterozygous, tiyenera kuyamba kuganizira za majini. Maselo anu ali ndi mbali yaitali kwambiri za DNA (deoxyribonucleic acid).
Izi ndizofunikira zomwe mumapeza kuchokera kwa makolo anu.
DNA imapangidwa ndi zigawo zingapo zomwe zimatchedwa nucleotides. Pali mitundu inayi yosiyanasiyana ya nucleotide mu DNA: adenine (A), guanine (G), cytosine (C), ndi thymine (T). M'kati mwa selo, DNA imapezeka kuti imakhala ndi ma chromosomes (omwe amapezeka awiri awiri awiri).
Zachibadwa ndi mbali zenizeni za DNA mwachindunji. Magulu awa amagwiritsidwa ntchito ndi makina ena mkati mwa selo kupanga mapuloteni enieni. Mavitamini ndizomwe zimagwiritsidwa ntchito pa maudindo ambiri m'kati mwa thupi, kuphatikizapo chithandizo chamagulu, kusindikiza maselo, kusakaniza mankhwala, komanso kuyenda. Selo limapanga mapuloteni (kunja kwa nyumba yake, amino acid) powerenga momwe magetsi amapezera mu DNA. Selo imagwiritsira ntchito mtundu wa kumasulira kuti ugwiritse ntchito chidziwitso mu DNA kupanga mapuloteni enieni omwe ali ndi mapangidwe ndi ntchito zinazake.
Majini ena enieni m'thupi amapanga maudindo osiyanasiyana. Mwachitsanzo, hemoglobini ndi molekyumu yamapuloteni yomwe imagwira ntchito yotengera mpweya m'magazi. Jini zingapo zosiyana (zomwe zimapezeka mu DNA) zimagwiritsidwa ntchito ndi selo kupanga mawonekedwe enieni a mapuloteni oyenera pa cholinga ichi.
Mumalandira DNA kuchokera kwa makolo anu.
Mwachidule, theka la DNA yanu imachokera kwa amayi anu, ndi theka lina la bambo anu. Kwa majini ambiri, mumalandira buku limodzi kuchokera kwa amayi anu ndi limodzi kuchokera kwa abambo anu. (Komabe, pali zosiyana ndi ma chromosomes awiri omwe amatchedwa chromosomes. Chifukwa cha njira zogonana zogonana, amuna amatha kukhala ndi mtundu umodzi wa majini ena.)
Kusiyanasiyana mu Genesis
Malamulo a anthu ali ofanana kwambiri: Makamaka 99 peresenti ya nucleotide yomwe ili mbali ya majini ndi ofanana ndi anthu onse. Komabe, pali kusiyana kosiyana pakati pa nucleotide m'magazi enaake. Mwachitsanzo, kusiyana kosiyana kwa jini kungayambe ndi kutsatira A T TGCT, ndipo kusiyana kwina kungayambitse A C TGCT m'malo mwake. Kusiyana kwakukulu kwa majini kumatchedwa alleles.
Nthawi zina kusiyana kumeneku sikumapangitsa mapuloteni kumapeto, koma nthawi zina amachita. Zingapangitse kusiyana kochepa mu mapuloteni omwe amachititsa kugwira ntchito mosiyana.
Munthu amati ndi ochepetsetsa kwa jini ngati ali ndi makope awiri ofanana ndi jini. Mu chitsanzo chathu, izi zikhoza kukhala makope awiri a jini omwe amayamba " T TGCT" kapena makope awiri a mawonekedwe omwe akuyamba "A C TGCT." Heterozygous amatanthauza kuti munthu ali ndi mitundu iwiri yosiyana ya jini kuchokera kwa kholo limodzi, ndi wina kuchokera kwa kholo lina).
Mu chitsanzo chathu, heterozygote ingakhale ndi mtundu umodzi wa jini kuyamba "A C TGCT" komanso kachilombo kena koyamba "A T TGCT."
Mitundu ya Matenda
Zambiri mwa kusinthaku sizinthu zazikulu, ndipo zimangopereka kusintha kwa anthu. Komabe, kusintha kwasintha kwina kungayambitse matenda aumunthu. Izi ndizo zomwe anthu akukamba ponena za "homozygous" ndi "heterozygous": kusintha kwa mtundu wina komwe kungayambitse matenda.
Chitsanzo chimodzi ndi kachilombo koyambitsa magazi . Mu kachilombo kamene kamayambitsa matenda, kamene kamasinthika mu nucleotide imodzi yomwe imayambitsa kusintha mu nucleotide ya jini (yotchedwa β-globin gene).
Izi zimapangitsa kusintha kwakukulu pa kasinthidwe kwa hemoglobini. Chifukwa cha ichi, maselo ofiira ofiira omwe amanyamula hemoglobin amayamba kutha msanga. Izi zingayambitse mavuto monga kuperewera kwa magazi ndi kupuma pang'ono.
Nthawi zambiri, pali njira zitatu zosiyana:
- Wina ali wochepetsetsa kwa β-globin gene (ali ndi makope awiri oyenera)
- Wina ndi heterozygous (ali ndi kachilendo kawirikawiri ndi yodabwitsa)
- Wina ndi wochepetsetsa chifukwa cha bzinjinasi yowopsa ya β-globin gene (ali ndi makope awiri osadziwika)
Anthu omwe ali heterozygous kwa sickle cell gene ali ndi kachilombo kamene kamakhala kosavomerezeka (kuchokera kwa kholo limodzi) ndi kabuku kamene kamakhudzidwa ndi jini (kuchokera kwa kholo lina). Anthu awa sapeza zizindikiro za matenda a anthia a sickle. Komabe, anthu omwe ali ovomerezeka pa jini wosachiritsika ya β-globin amapeza zizindikiro za matenda a sickle cell anemia.
Kodi Matenda a Heterozygotes Adzakhala ndi Matenda Achibadwa?
Inde, koma osati nthawi zonse. Zimatengera mtundu wa matenda. Mu mitundu ina ya matenda a majeremusi , munthu wodwalayo amatha kupeza matendawa.
Mu matenda omwe amachititsa zomwe zimatchedwa kuti majini akuluakulu, munthu amafunikira jini imodzi yokha ya jini kukhala ndi mavuto. Chitsanzo chimodzi ndi matenda a ubongo wa Huntington . Munthu yemwe ali ndi jini imodzi yokha (yomwe amachokera kwa kholo lililonse) adzalandira matendawa ngati heterozygote. (A homozygote amene amalandira mapepala awiri osasintha a makolo awo onse amathandizidwa, koma izi sizodziwika kwambiri ndi matenda opatsirana.)
Komabe, chifukwa cha matenda opatsirana, monga sickle cell anemia, heterozygotes sakhala ndi matendawa. (Komabe, nthawi zina akhoza kukhala ndi kusintha kwina kwina, malingana ndi matendawa.)
Nanga bwanji za Chromosomes za kugonana?
Chromosome ya kugonana ndi X ndi Y chromosomes zomwe zimawathandiza kusiyanitsa amuna ndi akazi. Azimayi amalandira ma X chromosomes, awiri kuchokera kwa kholo lililonse. Choncho, akazi amatha kuonedwa kuti ndi ochepetsetsa kapena oterewa pamtundu wina wa X chromosome.
Amuna ndi osokoneza pang'ono. Amalandira ma chromosomes awiri a kugonana: X ndi Y. Chifukwa chakuti ma chromosome awiriwa ndi osiyana, mawu akuti "homozygous" ndi "heterozygous" sagwiritsidwa ntchito pa ma chromosomes awiriwa pa amuna. Mwinamwake mwamva za matenda opatsirana pogonana, monga Duchenne muscular dystrophy . Izi zimapanga zosiyana zosiyana ndi zosiyana ndi matenda omwe amayamba kulandira kudzera mu ma chromosomes ena (otchedwa autosomes).
Heterozygote Phindu
Kwa matenda ena, ndizotheka kuti kukhala heterozygote kumapatsa munthu ubwino wake. Mwachitsanzo, zikuganiziridwa kuti kukhala heterozygote kwa galasi maselo a anemia geni angakhale otetezera malungo, poyerekezera ndi anthu omwe alibe chikhomo chosazolowereka.
Cholowa
Tiyeni tiganizire mitundu iwiri ya jini: A ndi. Pamene anthu awiri ali ndi mwana, pali zifukwa zingapo:
- Makolo onse awiri ndi AA. Ana awo onse adzakhala AA komanso (homozygous kwa AA).
- Makolo onse awiri ndi aa. Kenaka ana awo onse adzakhala aa (nayenso akugonjera kwa aa).
- Mmodzi kholo ndi Aa ndi kholo lina ndi Aa. Mwana wawo ali ndi mwayi wa 25% wokhala AA (homozygous), 50 peresenti yokhala Aa (heterozygous), ndipo 25 peresenti mwayi wokhala (homozygous)
- Mmodzi kholo ndi Aa ndipo winayo ndi aa. Mwana wawo ali ndi mwayi wa 50% wokhala Aa (heterozygous) ndipo 50 peresenti yokhala ndi (homozygous).
- Mayi mmodzi ndi Aa ndipo winayo ndi AA. Mwana wawo ali ndi mwayi wa 50% wokhala AA (homozygous) ndipo 50 peresenti yokhala Aa (heterozygous).
Mawu Ochokera
Kuphunzira za majini ndi zovuta. Ngati chibadwa chikuchitika m'banja lanu, musazengereze kukaonana ndi dokotala wanu za zomwe izi zikutanthauza kwa inu.
> Zotsatira:
> Berg JM, Tymoczko JL, Stryer L. Zamoyo Zamoyo. 6 th . New York, NY: WH Feedman ndi Company; 2007.
> Frenette PS, Atweh GF. Matenda a khungu la matenda: Zakafukufuku zakale, malingaliro atsopano, ndi lonjezo lam'tsogolo. Journal of Investigation Clinic . 2007; 117 (4): 850-858. lembani: 10.1172 / JCI30920.
> Nussbaum RL, McInnes RR, Willard HF, Hamosh A. Genetics mu Mankhwala 7 th . Philadelphia, PA: Sauders Elsevier; 2007.