Deoxyribonucleic acid. Model Crick and Watson

Ulwazi lokuqala malunga iimpawu eekhemikhali deoxyribonucleic acid abala kunyaka 1868. Kwinkulungwane yama-20 ukuya ekuqaleni novalo, oko kwabonisa ukuba molecule a Polymer yomgama. Njengoko nucleotides iiyunithi monomer isenzo iqulathe isiseko nitrogen, i pentose kunye neqela phosphate (a iswekile carbon ezintlanu-).

Deoxyribonucleic acid usenokuba isiseko kweentlobo ezimbini: a pyrimidine (thymine (T) kunye cytosine (C)) kunye purine (adenine (A) kunye guanine (G)). Umchiza ikhutshwa phandle usebenzisa nucleotide phosphodiester bond.

Izazi Watson and Crick kunyaka 1953, ukuthatha njengesiseko uhlalutyo X-ray ziikristale DNA bagqiba ukuba molecule lweenkobe ibandakanya iperi amatyathanga Polymer, emenza abe Helix kabini. Polynucleotide chain isilonda enye kwenye, zibanjwa kunye ngokusebenzisa iibhondi hydrogen akha phakathi edibanayo iziseko (macala ahambelanayo) ngemixokelelwane esahlukileyo. Xa iplagi abunjwe kuphela ngolu hlobo lulandelayo: adenine-thymine, guanine-cytosine. Ukuqina ikhutshwa phandle ngambini ezimbini yokuqala neyesibini - izitropu ezintathu hydrogen.

I deoxyribonucleic acid kabini-ndixakene linobude kubalwa inani leeperi nucleotides ngokufanayo ahambelanayo (BP). Kuba ezo molekyuli, enamakhulu ezigidi kunye amawaka leeyunithi ezitshatileyo m.n.p. athathwe kunye KB, ngokulandelelana kwazo. Ngenxa yoko, deoxyribonucleic chromosome yabantu acid imelwe omnye Helix kabini. Ubude bayo ngu 263 Mb ku

DNA nokuguqulwa (yokunyibilika) yinkqubo apho rhoqo double kweleli yomgama molecule singena coil karhulumente. Phezu yokunyibilika, kabini-molecule yahlulwe kwisekethe eyahlukileyo. Lobushushu apho isiqingatha deoxyribonucleic acid zanyibilika, kukho indawo yokunyibilika. Kuya kuxhomekeka kumgangatho ubume eziphilayo.

Njengoko sele kukhankanyiwe ngentla apha, ezi ngababini G-C ukuba yazinza bathathu, kunye iperi A-T - imixokelelwane ezimbini hydrogen. Ngako oko, ayanda umlinganiselo ngababini yokuqala, esitalini kokukhona kuya kuba molecule. Xa nokuguqulwa of a ngamaza 260 NM kwandisa ukufunxeka ukukhanya. Le isiphumo hyperchromic kwenza kube lula ukubonelela ukulawula imeko beemolekyuli lobume eziziisekondari. Ukuba isisombululo ngokucotha zipholile etyhidiweyo acid phakathi imisonto oluncedisanayo zamakhonkco thathaka kuyilwa kwakhona, inokuba isakhiwo ezijikeleze iyafana kusini na lokuzalwa (original). Le amandla DNA nokuguqulwa kunye iimolekyuli renaturation esekelwe indlela hybridization. Lusetyenziswa ukufunda isakhiwo nucleic.

Kabini-kweleli molecule, ekubeni umdlali ophethe lwe data yemfuza, kufuneka ihlangabezane neemfuno ezimbini eziphambili. Okokuqala, kufuneka lwenziwe (kukhutshelwe) ngokuchanileyo eliphezulu, yaye okwesibini, uku encoder i Yindibanisela iimolekyuli protein. Deoxyribonucleic acid, leyo imodeli iye yachazwa yi Watson kunye Crick, elihambelana ezi mfuno. Kufumaniseke ukuba ngokungqinelana nomgaqo complementarity, nomxokelelwane ngamnye molecule kunokuba isizalo ukuze kwakhiwe isekethi omtsha macala engqinelanayo. Ngenxa yoko, omnye ibakala phindana oko kwenzeka ukumatanisa iimolekyuli intombi ukuba ukulandelelana nucleotide efana naleyo kweyoqobo DNA. Ngaphezu koko, lo mxokelelwane gene nenesakhiwo kwiproteni ukulandelana acid acid ekhowudiweyo litshona.

Ekubeni, njengoko yenziwe DNA kawonke ukuvulwa kunye complementarity siseko, iinkqubo emiselweyo banoxanduva data ukucazulula ilifa kunye nokulawulwa kwezinto gene yokuqaphela. Ukongeza, le ngcamango saphuhliswa kwaye molekyuli amayeza.