Duba wurin da ke ƙasa sannan ka amsa tambayar daga baya a cikin harshe ɗaya kamar yadda wurin yake:  Passage: Kwayar halittar wani kwayar halitta tana dauke da dubban kwayoyin halitta, amma ba duk wadannan kwayoyin halittar ba ne suke bukatar su kasance masu aiki a kowane lokaci. Ana bayyana kwayar halitta lokacin da ake fassara shi zuwa mRNA kuma akwai hanyoyin salula da yawa na sarrafa maganganun kwayoyin halitta irin wannan cewa ana samar da sunadarai ne kawai lokacin da sel ke buƙata. Abubuwan da aka fassara sune sunadarai masu sarrafawa waɗanda ke ɗaure zuwa DNA, ko dai inganta ko hana fassarar kwayar halitta. A cikin kwayoyin halittar kwayoyin Escherichia coli, alal misali, akwai jerin kwayoyin halittar da ake buƙata don hada amino acid tryptophan. Koyaya, lokacin da aka riga aka sami tryptophan ga tantanin halitta, ba a buƙatar waɗannan kwayoyin don haɗin tryptophan. Kasancewar tryptophan kai tsaye yana shafar ayyukan kwayoyin halitta <unk> kwayoyin tryptophan suna haɗuwa da mai hana tryptophan (wani abu mai fassara), canza tsarin mai hanawa ta yadda mai hanawa ya haɗu da kwayoyin halitta. Mai hana tryptophan yana toshe rubutun da kuma bayyanar da kwayoyin halittar, ta haka ne ya haifar da mummunan tsari na tsari na tryptophan.  Tambaya: Kwayoyin halittar mutum guda nawa ne suke cikin kwayoyin halittar mutum?
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