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ÁÎËÜØÀß ËÅÍÈÍÃÐÀÄÑÊÀß ÁÈÁËÈÎÒÅÊÀ
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ÌÅÍÞ
ðåôåðàòû Ãåòåðîöèêëû ñ êîíäåíñèðîâàííîé ñèñòåìîé ÿäåð. Íóêëåîçèäû è èõ ïðîèçâîäíûå ðåôåðàòû

ÁÎËÜØÀß ËÅÍÈÍÃÐÀÄÑÊÀß ÁÈÁËÈÎÒÅÊÀ - ÐÅÔÅÐÀÒÛ - Ãåòåðîöèêëû ñ êîíäåíñèðîâàííîé ñèñòåìîé ÿäåð. Íóêëåîçèäû è èõ ïðîèçâîäíûå

Ãåòåðîöèêëû ñ êîíäåíñèðîâàííîé ñèñòåìîé ÿäåð. Íóêëåîçèäû è èõ ïðîèçâîäíûå

Ñîäåðæàíèå

 

Ãåòåðîöèêëû ñ êîíäåíñèðîâàííîé ñèñòåìîé ÿäåð

Ïóðèíîâûå îñíîâàíèÿ:

Íóêëåîçèäû

Íóêëåîòèäû

Íóêëåèíîâûå êèñëîòû

Ñòðóêòóðà ÐÍÊ:

Ñòðóêòóðà ÄÍÊ:

Áèîëîãè÷åñêàÿ ðîëü ÄÍÊ è ÐÍÊ

Ñïèñîê èñïîëüçîâàííîé ëèòåðàòóðû


Ãåòåðîöèêëû ñ êîíäåíñèðîâàííîé ñèñòåìîé ÿäåð


Ñþäà îòíîñÿòñÿ ñëåäóþùèå ñîåäèíåíèÿ:

1. Èíäîë

ÑÍ ßäðî èíäîëà ñîñòîèò èç àðîìàòè÷åñêîãî ÿäðà, ñêîíäåíñèðîâàííîãî ñ ïèððîëüíûì ÿäðîì.

 

             ÑÍ

   ÍÑ                 Ñ                 ÑÍ

                                                            

   ÍÑ                Ñ                  ÑÍ        

              ÑÍ             NH                 

 

2. Ñêàòîë - ïðîèçâîäíàÿ èíäîëà

ÑÍ Ñêàòîë è èíäîë ñîäåðæàòñÿ â îðãàíèçìå æèâîòíûõ. Îáðàçóþòñÿ ïðè ãíèåíèè , ïðè ïèùåâàðåíèè è îáëàäàþò íåïðèÿòíûì çàïàõîì, ïðè èõ îêèñëåíèè îáðàçóåòñÿ èíäîêñèë è ñêàòîêñèë:


             ÑÍ

   ÍÑ                 Ñ                 Ñ – ÑÍ3

 

   ÍÑ                Ñ                  ÑÍ        

              ÑÍ             NH                 

             ÑÍ                                       

   ÍÑ                 Ñ                 Ñ – ÎÍ             

                                                           -  Èíäîêñèë 

   ÍÑ                Ñ                  ÑÍ        

              ÑÍ             NH                 


             ÑÍ                                       

   ÍÑ                 Ñ                 Ñ – ÑÍ3            

                                                                -  Ñêàòîêñèë

   ÍÑ                Ñ                 Ñ – ÎÍ         

              ÑÍ             NH                 


ßäðî èíäîêñèëà âõîäèò â ñîñòàâ êðàñèòåëåé òèïà èíäèãî.

Ïóðèí – ñîñòîèò èç êîíäåíñèðîâàííûõ ãåòåðîöèêëîâ: ïèðèìèäèíà è èìèäàçîëà. Ïóðèí ýòî ñëàáîå îñíîâàíèå, óñòîé÷èâîå ê äåéñòâèþ îêèñëèòåëåé, õîðîøî ðàñòâîðèìîå â âîäå.

Ñàì ïóðèí áèîëîãè÷åñêîãî çíà÷åíèÿ íå èìååò, èìåþò îêñè è àìèíîïðîèçâîäíûå óðèíà, òàê íàçûâàåìûå ïóðèíîâûå îñíîâàíèÿ. Îíè âõîäÿò â ñîñòàâ íóêëåîòèäîâ è íóêëåèíîâûõ êèñëîò.


             ÑÍ

      N                Ñ                  N


   ÍÑ                Ñ                  ÑÍ        

                N             NH                 


Ïóðèíîâûå îñíîâàíèÿ:


1. Àäåíèí – 6 –àìèíîïóðèí

2. Ãóàíèí – 2 – àìèíî- 6- îêñèïóðèí

3. Ãèïîêñàíòèí – 6 – îêñèïóðèí – ïðîâîäèò îêèñëåíèå àäåíèíà

4. Êñàíòèí – 2,6 –äèîêñèïóðèí – ïðîâîäèò îêèñëåíèå ãóàíèíà.

5. Ìî÷åâàÿ êèñëîòà – 2,6,8 –òðèîêñèïóðèí

Ìî÷åâàÿ êèñëîòà ÿâëÿåòñÿ êîíå÷íûì ïðîäóêòîì îáìåíà ïóðèíîâûõ îñíîâàíèé â æèâûõ îðãàíèçìàõ è âûâîäèòñÿ èç îðãàíèçìà ñ ìî÷îé.  ïî÷âå ìî÷åâàÿ êèñëîòà ðàçëàãàåòñÿ ñ îáðàçîâàíèåì NH3. Ó æèâîòíûõ è ÷åëîâåêà ïðè íàðóøåíèè îáìåíà âåùåñòâ ìî÷åâàÿ êèñëîòà îòêëàäûâàåòñÿ â ñóñòàâàõ è âîçíèêàåò áîëåçíü ïîäàãðà. Ïóðèíîâûå îñíîâàíèÿ òàêæå ñóùåñòâóþò â äâóõ ôîðìàõ: åíîëüíàÿ è êåòîííàÿ, òî åñòü îáëàäàþò êåòî-åíîëüíîé òàóòîìåðèåé.

Àäåíèí

 

       Àäåíèí

               Ñ – NH2                                                                  C = NH

      N                 Ñ                N                                 HN                 C                  N

                                                                                                                                

   ÍÑ                Ñ                  ÑÍ                               HC                C                  CH

               N              NH                                                        N               NH

        Åíîëüíàÿ ôîðìà                                                      Êåòîííàÿ ôîðìà


Ãóàíèí

 

                           Ñ – ÎH                                                                  C = O

                N                 Ñ                N                                 HN                 C                  N

                                                                                                                                

     NH2 – C                 Ñ                  ÑÍ                      NH2 – C                C                  CH

                          N              NH                                                        N               NH

        Åíîëüíàÿ ôîðìà                                                      Êåòîííàÿ ôîðìà

 

Ãèïîêñàíòèí


               Ñ – OH                                                                   C = O

      N                 Ñ                N                                 HN                 C                  N

                                                                                                                                

   ÍÑ                Ñ                  ÑÍ                               HC                 C                 CH

               N              NH                                                        N               NH

        Åíîëüíàÿ ôîðìà                                                    Êåòîííàÿ ôîðìà

 

Êñàíòèí

 

                           Ñ – ÎH                                                                  C = O

                N                Ñ                 N                                  HN                 C                  N

                                                                                                                                

       HO – C                Ñ                  ÑÍ                          O = C                C                  CH

                          N              NH                                                      NH              NH

                 Åíîëüíàÿ ôîðìà                                                     Êåòîííàÿ ôîðìà

 

Ìî÷åâàÿ êèñëîòà

 

                           Ñ – ÎH                                                                  C = O

                N                Ñ                 N                                  HN                 C                  NÍ

                                                                                                                                

       HO – C                Ñ                 Ñ – ÎÍ                     O = C                C                  C = Î

                          N              NH                                                      NH              NH

                 Åíîëüíàÿ ôîðìà                                                     Êåòîííàÿ ôîðìà

Íóêëåîçèäû


Ýòî ñîåäèíåíèÿ, ñîñòîÿùèå èç ïóðèíîâûõ èëè ïèðèìèäèíîâûõ îñíîâàíèé (îñíîâàíèÿ áåðóòñÿ â êåòîííîé ôîðìå), ñâÿçàííûõ ñ ðèáîçîé èëè äåçîêñèðèáîçîé ( ôîðìà β,d- ôóðàíîâàÿ). Àçîòèñòûå îñíîâàíèÿ ñâÿçàíû ñ ãëèêîçèäíûì ãèäðîêñèëîì ðèáîçû èëè äåçîêñèðèáîçû ÷åðåç àòîì àçîòà â ïîëîæåíèè 9 ïóðèíîâîãî êîëüöà è à ïîëîæåíèè 3 ïèðèìèäèíîâîãî êîëüöà. Ýòè ñîåäèíåíèÿ â äàëüíåéøåì îáðàçóþò íóêëåîòèäû. Íàçâàíèå íóêëåîçèäà ñêëàäûâàåòñÿ èç íàçâàíèÿ ñîîòâåòñòâóþùåãî îñíîâàíèÿ, ñ îêîí÷àíèå «çèí». Íóêëåîçèä, â êîòîðûé âõîäèò àäåíèí, íàçûâàåòñÿ àäåíîçèíîì, ãóàíèí - ãóàíîçèíîì. Åñëè íóêëåîçèä ñîäåðæèò öèòîçèí, îí íàçûâàåòñÿ – öèòèäèíîì, óðàöèë – óðèäèíîì, åñëè òèìèí – òèìèäèíîì. Åñëè â íóêëåîçèä âõîäèò äåçîêñèðèáîçà, òî ê íàçâàíèþ äîáàâëÿåòñÿ ïðèñòàâêà «äåçîêñè», íàïðèìåð, äåçîêñèàäåíîçèí è òä. Íàïèøåì ðåàêöèþ îáðàçîâàíèÿ íóêëåîçèäà èç àäåíèíà è ðèáîçû:


               Ñ – NH2                                                                                                                  C – NH2                             

      N                 Ñ                N                                                                                     N                 C                N

                                                     

   ÍÑ                Ñ                  ÑÍ                       - ÍÎÍ                                               HC                 C                 CH

               N              NH                                                                                                         N               N

                              +                                   

ÑÍ2ÎÍ                   Π                      ÎÍ                                 CH2OH                     O                          

  Ñ          Í                              Í         Ñ                                      C          H                                   H         C

 Í          Ñ                               Ñ         Í                                     H           C                                   C          H

            ÎÍ                            ÎÍ                                                          OH                                 OH

             β-d-ðèáîôóðàíîçà                                                                             àäåíîçèí


Îáðàçîâàíèå íóêëåîçèäà èç öèòîçèíà è äåçîêñèðèáîçû:


                   Ñ – NH2                                                                                                                              C – NH2 

       N                   CH                                                                                                         N                   CH

                                                                                                                                                                       

O = C                  CH                                          - HOH                                              O = C                   CH

                  N                                                                                                                                  N

                           +                                                                                                                                  

CH2OH               O                   OH                                            CH2OH                O                             

   C         H                       H        C                                                C          H                       H         C

  H         C                        C         H                                               H         C                         C         H

            OH                      H                                                                     OH                        H

                                                                                                                   äåçîêñèöèòèäèí

 

Íóêëåîòèäû


Ýòî ñîåäèíåíèÿ íóêëåîçèäà ñ ôîñôîðíîé êèñëîòîé. Â ñîñòàâ íóêëåîòèäà ìîæåò âõîäèòü îäèí, äâà è òðè îñòàòêà ôîñôîðíîé êèñëîòû. Íóêëåîòèä, ñîäåðæàùèé ðèáîçó, íàçûâàåòñÿ ðèáîíóêëåîòèä, à ñîäåðæàùèé äåçîêñèðèáîçó – äåçîêñèðèáîíóêëåîòèä. Åñëè íóêëåîòèä èìååò îäèí îñòàòîê ôîñôîðíîé êèñëîòû, òî åñòü ÿâëÿåòñÿ ìîíîíóêëåîòèäîì, òî òàêèå ñîåäèíåíèÿ íàçûâàþòñÿ êèñëîòàìè è íàçûâàþò èõ â çàâèñèìîñòè îò íàçâàíèÿ îñíîâàíèÿ. Åñëè â èõ ñîñòàâ âõîäèò îñíîâàíèå:

Àäåíèí – àäåíèëîâàÿ êèñëîòà,

Ãóàíèí – ãóàíèëîâàÿ êèñëîòà,

Óðàöèë – óðèäèëîâàÿ êèñëîòà,

Òèìèí – òèìèäèëîâàÿ êèñëîòà,

Öèòîçèí – öèòèäèëîâàÿ êèñëîòà.

Åñëè â íóêëåîòèä âõîäèò äåçîêñèðèáîçà, òî ê ýòèì íàçâàíèÿì äîáàâëÿåòñÿ ïðèñòàâêà «äåçîêñè», íàïðèìåð, äåçîêñèàäåíèëîâàÿ êèñëîòà, äåçîêñèãóàíèëîâàÿ êèñëîòà è òä.

Íóêëåîòèäû ñ äâóìÿ è òðåìÿ îñòàòêàìè ôîñôîðíîé êèñëîòû íàçûâàåòñÿ òðåìÿ çàãëàâíûìè áóêâàìè: ïåðâàÿ áóêâà – íàçâàíèå îñíîâàíèÿ, âòîðàÿ áóêâà – ÷èñëî îñòàòêîâ ôîñôîðíîé êèñëîòû, òðåòüÿ áóêâà – ôîñôîðíàÿ êèñëîòà. Íàïðèìåð, ÀÄÔ: À- àäåíîçèí, Ä – äè(äâà), Ô – ôîñôàò, òî åñòü àäåíîçèíäèôîñôàò; ÀÒô – À- àäåíîçèí, Ò – òðè, Ô – ôîñôàò , òî åñòü àäåíîçèíòðèôîñôàò. Äè è òðè íóêëåîòèäû ÿâëÿþòñÿ àêêóìóëÿòîðàìè õèìè÷åñêîé ýíåðãèè â îðãàíèçìå.  ìîëåêóëàõ ýòèõ íóêëåîòèäîâ îñòàòêè ôîñôîðíîé êèñëîòû âÿçàíû ìåæäó ñîáîé ìàêðîýðãè÷åñêèìè ñâÿçÿìè. Îáîçíà÷àþòñÿ ìàêðîýðãè÷åñêèå ñâÿçè òàê – ~. Ïðè îòùåïëåíèè îñòàòêà ôîñôîðíîé êèñëîòû îò ýòèõ íóêëåîòèäîâ âûäåëÿåòñÿ áîëüøîå êîëè÷åñòâî ýíåðãèè, çà ñåò ðàñùåïëåíèÿ ìàêðîýðãè÷åñêèõ ñâÿçåé 34-46êÄæ/ìîëü (îáû÷íàÿ ñâÿçü äàåò 8-12 êÄæ/ìîëü). Âàæíåéøèìè èñòî÷íèêàìè ýíåðãèè â îðãàíèçìå ÿâëÿþòñÿ ÀÄÔ è ÀÒÔ.

Ñòðîåíèå ÀÒÔ:

 


                                                                                                                                                              C – NH2 

                                                                                                                                           N                  C                N

                                                                                                                                                                       

                                                                                                                                          HC               C                 CH

                                                                                                                                                      N              N

                                                          O           O           O                                                                                                   

                                                 HO – P ~ O – P ~ O – P ~ O – H2C                     O                             

                                                         OH        OH        OH            C         H                        H        C

                                                                                                     H         C                         C         H

                                                                                                               OH                      OH 

                                                                                                                                             Àäåíîçèí

                                                                                                                       Àäåíèëîâàÿ êèñëîòà

                                                                                                                                 ÀÄÔ

                                                                                                                       ÀÒÔ


Ïðè äåôîñôîðèëèðîâàíèè ÀÒÔ îáðàçóåòñÿ ÀÄÔ (è ÀÌÔ). Äåôîñôîðèëèðîâàíèå ÀÒÔ ñîïðîâîæäàåòñÿ îñâîáîæäåíèåì ýíåðãèè, êîòîðàÿ èñïîëüçóåòñÿ â êëåòêàõ äëÿ ðàçëè÷íûõ ïðîöåññîâ ñèíòåçà è äðóãèõ âèäîâ ðàáîò.  ñâîþ î÷åðåäü ÀÄÔ çà ñ÷åò ýíåðãèè, îñâîáîæäàþùåéñÿ ïðè îêèñëåíèè îðãàíè÷åñêèõ âåùåñòâ, ôîñôîðèëèðèóåòñÿ â ÀÒÔ.  êëåòêàõ îðãàíèçìà ïîñòîÿííî ïðîèñõîäèò ïðîöåññ ôîñôîðèëèðîâàíèÿ ÀÒÔ è ôîñôîðèëèðîâàíèÿ ÀÄÔ è ÀÌÔ. Ïîäîáíûì îáðàçîì ïðîèñõîäèò ôîñôîðèëèðîâàíèå è äðóãèõ íóêëåîòèäîâ. Âñå ýòè ñîåäèíåíèÿ â îðãàíèçìå èãðàþò âàæíóþ ðîëü â îáìåíå âåùåñòâ è ýíåðãèè, è, â ÷àñòíîñòè, â áèîñèíòåçå ëèïèäîâ è óãëåâîäîâ.



Íóêëåèíîâûå êèñëîòû


Ýòî âûñîêîìîëåêóëÿðíûå ïîëèìåðû, ìîíîìåðàìè êîòîðûõ ÿâëÿþòñÿ ìîíîíóêëåîòèäû, òî åñòü â ñîñòàâ íóêëåèíîâûõ êèñëîò â âèäå îòåëüíûõ çâåíüåâ âõîäÿò íóêëåîòèäû ñ îäíèì îñòàòêîì ôîñôîðíîé êèñëîòû. ×èñëî íóêëåîòèäíûõ çâåíüåâ äîñòèãàåò ó íèõ äåñÿòêîâ è ñîòåí òûñÿ÷. Íóêëåèíîâûå êèñëîòû äåëÿòñÿ íà äâà âèäà: ðèáîíóêëåèíîâûå êèñëîòû – ÐÍÊ (â èõ ñîñòàâ âõîäèò ðèáîçà); äåçîêñèðèáîíóêëåèíîâûå êèñëîòû – ÄÍÊ (â èõ ñîñòàâ âõîäèò äåçîêñèðèáîçà). Îòëè÷àþòñÿ îíè è ïî ñîäåðæàíèþ àçîòèñòûõ îñíîâàíèé.  ñîñòàâ ÐÍÊ âõîäÿò: àäåíèí, ãóàíèí, öèòîçèí è óðàöèë.  ñîñòàâ ÄÍÊ âõîäÿò: àäåíèí, ãóàíèí, öèòîçèí è òèìèí. Âñå íóêëåèíîâûå êèñëîòû ïîñòðîåíû îäíîòèïíî, à èìåííî: ïåðâîå íóêëåîòèäíîå çâåíî ñâÿçàíî ñ âòîðûì, âòîðîå ñ òðåòüèì, òðåòüå ñ ÷åòâåðòûì è òàê äàëåå; ÷åðåç êèñëîðîä îò ôîñôîðíîé êèñëîòû, òî åñòü ÷åðåç ôîñôîðíîýôèðíóþ ñâÿçü ìåæäó 3 óãëåðîäíûì àòîìîì ïåíòîçû îäíîãî ìîíîíóêëåîòèäà è ïÿòûì óãëåðîäíûì àòîìîì ïåíòîçû ñîñåäíåãî íóêëåîòèäà. ÄÍÊ ÿâëÿåòñÿ íîñèòåëåì ãåíåòè÷åñêîé èíôîðìàöèè. ÐÍÊ - ÿâëÿåòñÿ ïåðåíîñ÷èêîì èíôîðìàöèè ìåæäó ñèíòåçèðóþùèìèñÿ áåëêàìè.


Ñòðóêòóðà ÐÍÊ

                                      Ñ = O

                        HN                  CH

                     O =C                   CH                                                             Ó

                                     N

  –O – H2C        O                                    C – NH2

               C   H         H   C              N                                 N  

               H  C           C   H           HC                                 CH                                              À

                    O         OH                            N            N

          HO – P ~ O – H2C                    O                                     C = O

O                 C           H              H         C     HN                 CH     

                                       H         C               C          H       C                  CH                                                  Ó

  O             OH                  O       N

                                         HO – P ~O – H2C              O                                        C = O

                                                   O              C     H             H       C              N                                 N    

                                                                    H    C              C       H    NH2 –C                                 CH                            Ã

                                                                          O             OH                                N            N

                                                                HO – P ~ O – H2C                       O                                            C – NH2

                                                                         O                 C             H                H             C        N                  CH      Ö

                                                                                             H            C                 C              H  O=C                  CH

                                                                                                           O                OH                                N

                                                                                                 HO – P ~ O – H2C                O                    

                                                                                                          O                 C        H             H         C

                                                                                                                              H        C             C         H

                                                                                                                                         Î           ÎÍ


Ñòðóêòóðà ÄÍÊ

 

                                      Ñ = O

                        HN                  C – CH3

                     O =C                   CH                                                             Ò

                                      N

  –O – H2C        O                                    C – NH2

               C   H          H   C              N                                 N  

               H  C           C   H           HC                                 CH                                              À

                    O          H                              N            N

          HO – P ~ O – H2C                    O                                     C = O

O                 C           H              H         C     HN                 C – CH3     

                                       H         C               C          H       C                  CH                                                  Ò

  O               H                   O       N

                                         HO – P ~O – H2C              O                                        C = O

                                                   O              C     H             H       C              N                                 N    

                                                                    H    C              C       H    NH2 –C                                 CH                            Ã

                                                                          O              H                                  N            N

                                                                HO – P ~ O – H2C                       O                                            C – NH2

                                                                         O                 C             H                H             C        N                  CH      Ö

                                                                                             H            C                 C              H  O=C                  CH

                                                                                                           O                 H                                  N

                                                                                                 HO – P ~ O – H2C                O                    

                                                                                                          O                 C        H             H         C

                                                                                                                              H        C             C         H

                                                                                                                                         O            H


Áèîëîãè÷åñêàÿ ðîëü ÄÍÊ è ÐÍÊ


 ñîñòàâ êëåòîê âõîäèò òðè òèïà ÇÍÊ:

1. Èíôîðìàöèîííàÿ ÐÍÊ (è -ÐÍÊ) èëè ìàòðè÷íàÿ ÐÍÊ (ì-ÐÍÊ) . Îíà ñèíòåçèðóåòñÿ â ÿäðå è åå íóêëåîòèäíûé ñîñòàâ áëèçîê ê íóêëåîòèäíîìó ñîñòàâó ÄÍÊ. È-ÐÍÊ ñíèìàåò ñ ÄÍÊ èíôîðìàöèþ è ïåðåíîñèò åå ê ìåñòó ñèíòåçà áåëêà â ðèáîñîìó. Ïîòîìó îíà âûïîëíÿåò ðîëü ìàòðèöû äëÿ ñèíòåçà áåëêà. Ñóùåñòâóþò ðàçíîîáðàçíûå ôóíêöèè è-ÐÍÊ êàê ïî íóêëåîòèäíîìó ñîñòàâó, òàê è ïî âåëè÷èíå ìîëåêóë, òàê êàê êàæäûé áåëîê äëÿ ñâîåãî ñèíòåçà òðåáóåò ñâîåé ìàòðèöû, òî åñòü ñâîåé ÐÍÊ.

2. Òðàíñïîðòíûå ÐÍÊ (ò-ÐÍÊ) – âûïîëíÿþò ðîëü ïåðåíîñ÷èêà àìèíîêèñëîò ê ìåñòó ñèíòåçà áåëêà. Îäíà ñïåöèôè÷åñêàÿ ò-ÐÍÊ îñóùåñòâëÿåò òðàíñïîðò îäíîé àìèíîêèñëîòû.

3. Ðèáîñîìàëüíûå ÐÍÊ (ð- ÐÍÊ) – âõîäÿò â ñîñòàâ ðèáîñîì (ñóáêëåòî÷íûõ îáðàçîâàíèé), â êîòîðûõ ïðîèñõîäèò áèîñèíòåç áåëêà. Ñ÷èòàåòñÿ, ÷òî ð – ÐÍÊ âûïîëíÿåò ñòðóêòóðíóþ ðîëü: â ñî÷åòàíèè ñ ñîîòâåòñòâóþùèìè áåëêàìè îíà îáðàçóåò ñòðóêòóðó ðèáîñîìû.

ÄÍÊ ñîäåðæèò èíôîðìàöèþ íàñëåäñòâåííîñòè. Îòäåëüíûå ó÷àñòêè äëèííîé öåïè ÄÍÊ ñîäåðæàò àçîòèñòûå îñíîâàíèÿ â îïðåäåëåííîé ïîñëåäîâàòåëüíîñòè. Ýòè ó÷àñòêè è ÿâëÿþòñÿ íîñèòåëÿìè îïðåäåëåííûõ íàñëåäñòâåííûõ ïðèçíàêîâ.

Ïåðåäà÷à íàñëåäñòâåííûõ ïðèçíàêîâ ïðîèñõîäèò ïðåèìóùåñòâåííî ñ ïîìîùüþ ÄÍÊ ïðè äåëåíèè ÿäåð êëåòîê. Ïðè ïîìîùè ÄÍÊ â êëåòêå èäåò ñèíòåç ÐÍÊ, êîòîðûé îáåñïå÷èâàåò ñèíòåç ñïåöèôè÷åñêèõ áåëêîâ.

Ìîëåêóëà ÐÍÊ ïðåäñòàâëÿåò ñîáîé îäíîöåïî÷å÷íóþ ñïèðàëü, òî åñòü èìååò òîëüêî ïåðâè÷íóþ ñòðóêòóðó, êîòîðàÿ ïîêàçûâàåò ïîñëåäîâàòåëüíîñòü íóêëåîòèäíûõ çâåíüåâ. Ìîëåêóëà ÄÍÊ èìååò åùå è âòîðè÷íóþ è òðåòè÷íóþ ñòðóêòóðó. Âòîðè÷íàÿ ñòðóêòóðà ÄÍÊ èìååò äâóõöåïî÷å÷íóþ ñïèðàëü. Êàæäàÿ öåïü ïðåäñòàâëÿåò ñîáîé ïîëèíóêëåîòèä, â êîòîðîì äèýôèðíîé ñâÿçüþ ñâÿçàíû äðóã ñ äðóãîì ìîíîíóêëåîòèäû.  öåïè ìîíîíóêëåîòèäû ðàñïîëîæåíû òàêèì îáðàçîì, ÷òî àçîòèñòûå îñíîâàíèÿ èõ íàõîäÿòñÿ âíóòðè, à ïåíòîçà è ôîñôîðíàÿ êèñëîòà – ñíàðóæè.

Äâå ïàðàëëåëüíî èäóùèå öåïè, îáâèòûå âîêðóã îáùåé îñè, ñâÿçàíû äðóã ñ äðóãîì ñâîèìè àçîòèñòûìè îñíîâàíèÿìè âäîëü âñåé ìîëåêóëû ÄÍÊ ñ ïîìîùüþ âîäîðîäíûõ ñâÿçåé.

Ïîñëåäîâàòåëüíîñòü ðàñïîëîæåíèÿ àçîòèñòûõ îñíîâàíèé â êàêîé-ëèáî îäíîé èç äâóõ öåïåé ìîæåò áûòü ëþáàÿ, íî ïîñëåäîâàòåëüíîñòü ðàñïîëîæåíèÿ àçîòèñòûõ îñíîâàíèé â äðóãîé öåïè áóäåò íàõîäèòüñÿ â ñòðîãîé çàâèñèìîñòè îò ïîñëåäîâàòåëüíîñòè îñíîâàíèé â ïåðâîé öåïè. Òî åñòü äîëæíî ñîáëþäàòüñÿ ïðàâèëî ×àðãîôà, êîòîðîå çàêëþ÷àåòñÿ â òîì, «÷òî ñîäåðæàíèå â ÄÍÊ ïóðèíîâ ðàâíî ñîäåðæàíèþ ïèðèìèäèíîâ», à èìåííî ñîäåðæàíèå àäåíèíà ðàâíî ñîäåðæàíèþ òèìèíà (À=Ò), ñîäåðæàíèå ãóàíèíà – ñîäåðæàíèþ öèòîçèíà (Ã=Ö). Ïàðû àäåíèí-òèìèí è ãóàíèí - öèòîçèí ÿâëÿþòñÿ êîìïëåìåíòàðíûìè (äîïîëíÿþùèìè) äðóã äðóãó. Ýòè ïàðû ñîåäèíåíû âîäîðîäíûìè ñâÿçÿìè. Èç ýòîãî ñëåäóåò, ÷òî ìàêðîìîëåêóëà ÄÍÊ ñêëàäûâàåòñÿ èç äâóõ êîïëåìåíòàðíûõ äðóã äðóãó öåïåé.

Òðåòè÷íàÿ ñòðóêòóðó ÄÍÊ ñâÿçàíà ñ ïðîñòðàíñòâåííûì ðàñïîëîæåíèåì äâîéíîé ñïèðàëè, îíà íå ìîæåò áûòü çàêðó÷åíà â êëóáîê èëè áûòü â âèäå êîìïàêòíîé ïàëî÷êè.

Íóêëåèíîâûå êèñëîòû – âåùåñòâà áåëîãî öâåòà, âîëîêíèñòîãî ñòðîåíèÿ, ïëîõî ðàñòâîðèìû â âîäå â ñâîáîäíîì ñîñòîÿíèè, íî õîðîøî ðàñòâîðèìû â âèäå ñîëåé ìåòàëëîâ, îíè òàêæå õîðîøî ðàñòâîðèìû â ñîëåâûõ ðàñòâîðàõ.

ÄÍÊ íàõîäèòñÿ ïðåèìóùåñòâåííî â ÿäðå êëåòêè (â ñîñòàâå õðîìîñîì), îäíàêî íåñêîëüêî ïðîöåíòîâ îáùåé êëåòî÷íîé ÄÍÊ ñîñðåäîòî÷åíî â ìèòîõîíäðèÿõ, õëîðîïëàñòàõ ðàñòèòåëüíûõ êëåòîê. ÐÍÊ âñòðå÷àåòñÿ êàê â ÿäðå, òàê è â öèòîïëàçìå.


Ñïèñîê èñïîëüçîâàííîé ëèòåðàòóðû

 

1) Áèîëîãè÷åñêàÿ õèìèÿ./Ïîä ðåä.Þ.Á.Ôèëèïïîâè÷à,Í.È.Êîâàëåâñêàÿ,Ã.À.Ñåâàñòüÿíîâîé . - Ì., 2005

2) Áèîõèìèÿ./Ïîä ðåäàêöèåé Â.Ã.Ùåðáàêîâà. - ÑÏá., 2003

3) Âîëüõèí Â.Â. Îáùàÿ õèìèÿ. Èçáðàííûå ãëàâû. - ÑÏá, Ì, Êðàñíîäàð., 2008


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