Gani Bambanci a Alleles
Idan kun kasance kuna karatun game da yanayin kwayoyin halitta, kuna iya ganin kalmomin "homozygous" ko "heterozygous"? Amma menene waɗannan kalmomi suke nufi? Kuma menene sakamakon da ake samu na kasancewa "homozygous" ko "heterozygous" don takamaimai?
Mene ne Gene ?
Kafin muyi bayanin homozygous da heterozygous, dole ne mu fara tunani game da kwayoyin. Kowace ɓangarenku yana ƙunshe da DNA (deoxyribonucleic acid) mai tsawo.
Wannan abu ne mai kyau wanda ka samu daga iyayenka.
DNA ya ƙunshi jerin mutum wanda ake kira nucleotides. Akwai nau'o'i hudu na nucleotides a cikin DNA: adenine (A), guanine (G), cytosine (C), da kuma thymine (T). A cikin tantanin halitta, ana samuwa DNA da yawa zuwa cikin chromosomes (samo a cikin nau'i-nau'i 23).
Genes suna da ƙananan sassan DNA tare da manufar dalili. Wadannan sassan suna amfani da su a cikin tantanin halitta don yin sunadaran sunadarai. Sunadaran su ne ginshiƙan ginin da aka yi amfani da su a cikin matsayi mai mahimmanci a cikin jiki, ciki har da goyon bayan tsarin, siginar tantanin halitta, haɓakar haɓakar haɗari, da motsa jiki. Sel ɗin yana sa sinadaran (daga gininsa, amino acid) ta hanyar karanta jerin nucleotides da ke cikin DNA. Tantanin yana amfani da irin tsarin fassara don amfani da bayani a cikin DNA don gina wasu sunadarai masu mahimmanci tare da ƙayyadaddun tsari da ayyuka.
Musamman kwayoyin jiki a jiki sun cika matsayi. Alal misali, hemoglobin wata kwayar sunadaran gina jiki ce wadda ke aiki don ɗaukar oxygen cikin jini. Dabbobi daban-daban (samuwa a cikin DNA) suna amfani da tantanin halitta don samar da siffofin gina jiki musamman don wannan dalili.
Za ka gaji DNA daga iyayenka.
Yayin da yake magana, rabi na DNA ta fito ne daga mahaifiyarka, da sauran rabi daga mahaifinka. Ga mafi yawan kwayoyin halitta, ka sami kaya daga mahaifiyarka kuma ɗaya daga mahaifinka. (Duk da haka, akwai wani banda ya shafi wani nau'i na chromosomes da ake kira jima'i na chromosomes. Saboda hanyar jima'i na chromosomes ke aiki, maza zasu sami gado ɗaya daga wasu kwayoyin.)
Bambanci a cikin Yanayin
Kwayoyin halittar kwayoyin halitta sunyi kama da juna: Kusan kashi 99 cikin dari na nucleotides da ke cikin kwayoyin halitta iri daya ne a cikin dukan mutane. Duk da haka, akwai wasu bambanci a cikin jerin nucleotides a cikin wasu kwayoyin. Alal misali, bambancin jinsin iya farawa da jerin A T TGCT, kuma wani bambancin zai fara A C TGCT maimakon. Wadannan bambancin bambancin kwayoyin an kira su.
Wani lokaci wadannan bambancin ba sa bambanci a furotin na ƙarshe, amma wani lokaci sukanyi. Suna iya haifar da ƙananan bambanci a cikin furotin wanda ya sa ya yi aiki kaɗan daban.
An ce mutum ya zama homozygous don jinsin idan suna da nau'i guda biyu na mahaifa. A cikin misalinmu, wannan zai zama nau'i biyu daga cikin jigon halittar fara "A T TGCT" ko biyu kofe daga cikin fasalin fara "A C TGCT." Harshen Heterozygous yana nufin cewa mutum yana da nau'i daban daban na jinsin (wanda aka gaji daga iyaye ɗaya, da ɗaya daga iyayensa).
A cikin misalinmu, mai amfani da harshe yana da nau'i daya daga cikin jigon halittar "A C TGCT" da kuma wani nau'i na jigon fara "A T TGCT."
Cututtuka na cututtuka
Da yawa daga cikin wadannan maye gurbin ba babban abu ne ba, kuma suna taimakawa ne kawai ga bambancin mutum na al'ada. Duk da haka, wasu ƙayyadaddun takamaimansu na iya haifar da cututtukan mutum. Wannan shine sau da yawa abin da mutane ke magana game da lokacin da suka ambaci "homozygous" da "heterozygous": wani nau'i na mutation wanda zai iya haifar da cutar.
Ɗaya daga cikin misalai shi ne anemia mai sikila . A cikin ƙwayar cutar sikila, akwai maye gurbi a cikin wani nucleotide guda daya wanda ke haifar da canji a cikin nucleotide na wata (mai suna β-globin gene).
Wannan yana haifar da muhimmin canji a cikin daidaituwa na haemoglobin. Saboda wannan, jinin jinin dauke da haemoglobin fara fara karya. Wannan zai haifar da matsalolin kamar anemia da rashin ƙarfi na numfashi.
Kullum magana, akwai hanyoyi uku daban-daban:
- Wani mutum homozygous ne don nau'in β-globin na al'ada (yana da nau'i biyu na al'ada)
- Wani mutum ne heterozygous (yana da al'ada ɗaya da ɗaya kwafi)
- Wani mutum ne homozygous ga mahaifa β-globin mahaukaci (yana da nau'i guda biyu)
Mutanen da suke heterozygous don raunin sikila suna da nau'i daya daga cikin mahaifa (daga iyaye daya) da kuma daya daga cikin nau'in mahaifa (daga sauran iyaye). Wadannan mutane ba su samo alamar cututtuka na anemia ba. Duk da haka, mutanen da suke homozygous don nau'in β-globin mahaukaci suna samun alamun cututtuka na anemia sickle cell.
Shin Hanyoyin Harshen Harshen Tsira Sun Samu Kwayoyin Halitta?
Ee, amma ba koyaushe ba. Ya dogara da irin cutar. A wasu nau'o'in cututtuka na kwayoyin halitta , mutum mai suna heterozygous kusan ya sami cutar.
A cikin cututtuka da abin da ake kira jinsuna masu rinjaye, mutum yana buƙatar guda ɗaya kawai ne kawai don samun matsalolin. Ɗaya daga cikin misalai shi ne cutar rashin lafiya na cutar Huntington . Mutumin da ke da kwayar cutar daya (wanda aka gado daga iyaye ɗaya) zai kusan samun cutar a matsayin heterozygote. (Yarin da zai sami nau'i biyu na cututtukan cutar daga iyaye duka za a shawo kan su, amma wannan bai zama na kowa ba saboda yawan kwayoyin cututtuka.)
Duk da haka, don cututtuka na sake dawowa, kamar anemia na sickle cell, heterozygotes ba sa samun cutar. (Duk da haka, wani lokaci ana iya samun wasu canje-canje masu kyau, dangane da cutar.)
Menene Game da Chromosomes da Jima'i?
Kwayoyin jima'i sune X da Y sunadarai da ke taka muhimmiyar bambancin jinsi. Mata suna da kwakwalwa guda biyu na X, daya daga kowane iyaye. Saboda haka mace za a iya daukan homozygous ko heterozygous game da takamaimai kan X chromosome.
Maza suna da rikicewa. Suna haɗu da jinsin jima'i biyu na chromosomes: X da Y. Saboda wadannan chromosomes biyu sun bambanta, kalmomin "homozygous" da "heterozygous" ba su dace da waɗannan chromosomes biyu akan maza ba. Kila ka ji labarin cututtuka da aka danganta da jima'i, kamar Duchenne muscular dystrophy . Wadannan suna nuna nau'in haɗin gine-gine fiye da nagartaccen cututtuka ko ƙananan cututtuka wanda aka gada ta sauran chromosomes (wanda ake kira autosomes).
Hanyoyin amfani da Hurorozygote
Ga wasu kwayoyin cututtuka, yana yiwuwa yiwuwar kasancewa a heterozygote ya ba mutum wani amfani. Alal misali, anyi tunanin cewa kasancewa a heterozygote don raunin anemia na sickle cell zai iya kasancewa mai mahimmanci don cutar malaria, a kwatanta ga mutanen da basu da kwafi mara kyau.
Gida
Bari mu ɗauka nau'i biyu na wata: A da. Lokacin da mutane biyu suna da yaro, akwai hanyoyi masu yawa:
- Duk iyaye biyu ne AA. Dukan 'ya'yansu za su kasance AA da (homozygous na AA).
- Duk iyaye biyu ne. Sa'an nan kuma dukan 'ya'yansu za su kasance aa da (homozygous ga aa).
- Ɗaya iyaye ne Aa kuma wani iyaye ne Aa. Yaron ya sami damar kashi 25 cikin kasancewa na AA (homozygous), kashi 50 bisa dari na kasancewar Aa (heterozygous), da kuma kashi 25 cikin dari na kasancewa (homozygous)
- Ɗaya iyaye ne Aa kuma ɗayan yana da aa. Yaransu yana da kashi 50 cikin dari na kasancewar Aa (heterozygous) da kuma damar kashi 50 bisa dari na kasancewa (homozygous).
- Ɗaya iyaye ne Aa kuma ɗayan yana AA. Yaransu yana da damar kashi 50 bisa dari na kasancewar AA (homozygous) da kuma damar kashi 50 na kasancewar Aa (heterozygous).
Kalma Daga
Nazarin kwayoyin halitta yana da hadari. Idan yanayi na kwayar halitta ke gudana a cikin iyalinka, kada ka yi shakka ka tuntuɓi likitanka na kiwon lafiya game da abin da wannan ke nufi a gare ka.
> Sources:
> Berg JM, Tymoczko JL, Stryer L. Biochemistry. 6 th ed. New York, NY: Manyan Ma'aikata da Kamfani; 2007.
> Siffar labarai PS, Atweh GF. Cutar cutar sikila: tsohuwar binciken, sababbin ra'ayoyi, da alkawurran gaba. Jaridar Clinical Bincike . 2007; 117 (4): 850-858. Doi: 10.1172 / JCI30920.
> Nussbaum RL, McInnes RR, Willard HF, Hamosh A. Genetics in Medicine 7th ed. Philadelphia, PA: Sauders Elsevier; 2007.