DNA REPLICATION

DNA REPLICATION SUMMARY

-To summarize, DNA replication is a semiconservative process, which means there is one parent strand and one daughter strand in the replicated DNA.
-Each parent strand is a template for ordering nucleotides to make a new complimentary strand.
-There are many sites of replication on a strand of DNA called "replication bubbles", with replication forks on each ends.
-The strands in the double helix are antiparallel, so one strand runs in 5' -> 3' direction, while the other runs in 3'->5' direction  (A new DNA strand can only elongate in the 5'->3' direction)

Leading Strand: (continous replication)
 -form a continuous complimentary strand
 -5' -> 3' using DNA polymerase III.
 -into the fork

Lagging strand:
-From 5' ->3', it forms pieces from Okazaki fragments.
-strand are copied away from the fork.
-First RNA primase lace down the RNA primer, the DNA polymerase III (a.k.a. the little brother) lace down new DNA. This process repeats again and again continously. Then DNA Plymerase I (the bigger brother) replaces RNA primer with DNA. Fnally DNA ligase comes and link OKAZAKI fragmets.

 

 

Definition of key ENZYMES:

 

DNA helicase unwinds the double helix.
DNA gyrase (bacterial enzyme) relieves the tension (produced from unwinding of DNA).
Single-stranded binding proteins (SSBs) keeps separated strands of DNA apart.
Primase (RNA polymerase) makes primer, which signals Polymerase III to make complementary strand.
DNA Polymerase III then grabs nucleotides to make complementary strands of DNA.
DNA Polymerase I then replaces the RNA primer with DNA.
DNA ligase join all the gaps that are present on the daughter strands.



 DNA REPLICATION VIDEO WEBSITES:

1) http://www.youtube.com/watch?v=4jtmOZaIvS0&feature=related2) http://www.youtube.com/watch?v=teV62zrm2P0&feature=related