Kalmar "karshen m" yawanci tana nufin takamaiman halayen ƙwayoyin DNA waɗanda ke haifar da aikin wasu enzymes, musamman ƙuntatawa enzymes. A cikin ilmin halitta, ƙuntatawa enzymes sunadaran sunadaran da ke ganewa kuma suna ɗaure ga takamaiman jerin DNA, kuma suna manne DNA a ko kusa da waɗannan jeri. Lokacin da enzyme na ƙuntatawa ya yanke DNA, sau da yawa yakan haifar da gajeriyar rataye guda ɗaya a ƙarshen ɓangarorin DNA da aka yanke. a sauƙaƙe samar da haɗin gwiwar hydrogen tare da ƙarin jeri. Za a iya amfani da sakamakon haɗin ginin tushe don haɗa gutsuttsuran DNA tare da madaidaitan ƙarewa tare, yana ba da damar ƙirƙirar ƙwayoyin DNA na sake haɗawa. Ana amfani da wannan tsari sosai a cikin ƙwayoyin ƙwayoyin cuta, injiniyan kwayoyin halitta, da sauran dabarun sarrafa kwayoyin halitta. yana manne da wani abu, sau da yawa yana yin wahalar rabuwa ko rabuwa. Duk da haka, farkon kuma mafi takamaiman amfani da kalmar yana cikin fagen ilimin ƙwayoyin cuta don bayyana rataye guda ɗaya da aka samar ta hanyar hana enzymes yayin tsagewar DNA.