DNA synthesis molec DNA-replication.pptx

Describe Molecular path of replication

1. C e ntral do g ma R e pli cat i o n Transcrip t io n Tra n s l at i on PROTEIN Revers e t ranscri pt ion

2. DNA replication is a biological process that occurs in all living organisms and copies their exact DNA. It is the basis for biological inheritance. is the process of synthesis d a ug h t e r DNA fr o m p a r e n t a l D NA b y of the e n z y m e D NA P o l m e r ase. PPi (dNMP) dNTP - (dNMP ) D NA Le n gthe n e d DNA

3. D NA Replication Par e ntal s trand Daughter s tand

4. D NA R e pli ca ti o n • A reaction in which daughter DNAs are synthesized using the parental DNAs as the template. • • Transferring the the d e s c e nd a n t g e n e r a t i o n fidelity. R e plic a t ion to with a high P ar e n t a l DNA D a u g h t e r D NA

5. Three possible replication patterns: Semiconservative replication Conservative replication Dispersive replication

6. Aft e r one r o u n d of r eplica t ion Semi c on s ervativ e r e pli c ation (A) 0MK -< (8 ) C on se rvativ e r e pli c ation VO0MK • Di s p e r s iv e r e pli c ation

7. Each parent strand serves as a template for a new strand and the two new DNA s t r a n d s e a c h have one old strand and one new • € • € • • • • • e • -- • � P a r e nt stra nd s € • • e • • C �

8. • • • • Semi-conservative replication Bidirectional replication Semi-continuous replication High fidelity

9. [1958] demonstrated Semiconservative replication DNA o r treted a n d centrifuged to utitrurn n €CT dnatty grad int origin 8 al parent t no.cul M ytr@ D N A MN I4N » ct» torti-on dug h tr roe l o 3 tlco # n de 3 ten 8 tion daug h ter molecu l e L e DNA ( ' N t e Hybrid DN A

10. » S e m i c o n s er va t i v e R e p l i c a t i o n H alf of the pare nt a l D NA m o l ec ul e is co n se r ve d i n eac h n ew doubl e h e li x , p aire d w ith a n ew l y s yn th es i ze d co m p l e m e nt ary s tr a nd . Thi s i s ca ll e d s e mi co n s e r va ti ve re pli ca ti o n.

11. Bidirectional Replication • Repli ca tion s tart s from un w indin g th e d s D N A at a particular point ( c a ll e d ), f o llow e d by th e sy nth e s i s o n e a c h s trand . Th e p a r e ntal d s DN A a nd t w o n ew l y f o rm e d d s DNA form a Y - s hap e s tru c tur e c all e d •

12. 3' 5 ' " Lea din g str and ' g r 5 ' 3' Direction o f movement o f rep li ca tion fork s ' Oka za ki • fragme n ts \_ g · 3' ' " "" 3 ' Lagging 5 · str an d

13. Replication Enzymes & Proteins • D NA P o l ymerase - M a t c h es th e c orr ec t nu c l e otid es th e n j o in s / pol y m e ri zes a dj ace nt nu c l e otid es to eac h o th er. • Helicase - U n w ind s th e D N A a nd m e lt s . 1t . • P rimase - P r o v i d e s a n s tart pol y meri za tion. A prim e r to

14. � S in g le Strand Bindin g Prot e in s - K ee p th e D N A s in g l e s trand e d a ft e r it h as b ee n m e lt e d b y h e li c a se • G y ra s e - A topi s om e r ase that R e li eves tor s ional s train in th e DNA mol ec ul e . • Li g a s e - Join s a d j a c e n t DNA s t r a n d s t o g e t h e r (fixe s " n i c k s " ) • Telomera s e - Fini s he s off the end s of s tr a nd s in Eukar y ot es DNA

15. DNA Polymera s e s of Prokar y ote s DNA Pol merase-1 • The first (DNA Pol -I ) was discovered in 1958 by Arthur Kornberg who received Nobel Prize in physiology & medicine 1959. in • DNA Polymerase is considered as K o r n b e r g E n z v m e .

16. • Later , were identified . and • All of th e m po ss e ss the biolo g ical acti v it y . following 1.5'-)3 ' Pol y m e r se acti v it y 2. E xonucl e a se activity

17. Exo n uc l ease f un ct i o n s 3 » 5 ' e xo nu c l ea s e a c ti v i ty exc i s e mi s mat c h e d nul eo tid e s 5 ' » 3' exo nu c l ease ac ti v i ty r e mo ves p r i m e r e x c i se mu t at e d seg m e nt or

18. D NA Polm e ra se - I • Mainly responsible for repairing DNA damage

19. D NA Pol y m e ra se - I I • T e m p o r a r i l y f un c ti on a l wh e n D NA - p o l and D NA -pol III are not functional. • Still capable for doing I • Participat es in proce ss .

20. DNA Polymerase - III • A he t e r o d im e r enzyme c o mpo s e d o f ten d i f f e r e nt s u b uni t s • Having the polymerization activity (10 nt/min) • T h e t r u e enzyme r e s p o n s i b l e f o r th e p r o c e ss

21. Structure of DNA-pol III h as 5 ' » 3 ' : p o lym e ri zi n g act i vity & : h as 3 ' » 5 ex onu c lea se ac t i v it y a nd p l ays a k ey rol e t o e n s ur e t h e r e pli c ati o n fid e li ty. () : m a intain h e t e r od im e r s tru c tu re

22. DNA Replication , like al l bio l ogical po l ymer i zation processes, proceeds i n t hr ee enzy m atica l ly catalyzed and coord i nated steps : init i at i on elongatio n and ter m ina t ion

23. D N A Rep l i cation D NA r e p l ica ti on in cl u d e s : -- i n i tiat i on -- r ep l i c at i on beg i ns at an ori gi n of replication - elongation - n e w s tr an d s o f DNA a r e sy n t hesized by DNA po l ymerase t erm i nation re p l i cat i o n is t e rm i n a t e d d i ffere n tl y i n p r o k ary o tes and euk a r y o t es

24. Initiation

25. Cont .. The separation of the two s ingle strand s of DNA creates 'fork'. a'Y' shape called a replication • • F t a $ as° " .. - • dd " Replicat i on Fork Form i ng

26. A Prima s e • • Al s o c alled Prim ase u s i n g t h e i s able to sy nthe s iz e primers a s the s ub s trat e and as the t e mp l ate . ar e s hort RNA fra g ment s of a nucleotide s lon g. s ev e ral

27. A P ri ase • • Al s o c alled Prim ase i s abl e to sy nthe s i z e primer s NTPs a s th e s ub s trate a nd u s in g free th e ssDNA a s the t e mpl a t e. a r e s hort RNA fra g m e nt s o f a seve r a l nu c l eo tid es l o n g.

28. l pri me r 5 5 5 5 N ew DNA DNA te m pla t e 5' 5 5 5 ! Pti mase 5' 3 R . NA ONA polym trasc 11 1

29. DNA replication fork l eadi n g strand 3' DNA unzips continuous 3 , 5 discontinuous okazaki fragment > ' ' lagg i ng strand s ·

30. 3 5 ' 5 N ewly Sy nth e si z e d DNA St ra nd 3 ' } a s s ' hhhlhhhhhl ldhdlllll, Di rec t i on o f R e p li c at i o n F o r k M oveme nt O k a z a k i F ragme nt s Oka zali 'ragme n t s

31. ZIZIISEIEESZI3 I3L. C h romosome F ree nucleotides T DNA poly me ra s e l ead i n g s tr a n d H elicas e lagging st r and Original ( t e m p l a t e ) DN A 7 7 ! Re p li cation f o r k a Adenin e c T hymin e - Cytosin e - Gua n i n e D NA polymerase O riginal ( t e mplat e) D N A strand C ) r

32. Once all of the bases are matched up (A with T, C with G), an enzyme called exonuclease strips away the primer(s). The gaps where the primer(s) were are then filled by yet more complementary nucleotides .