1.When a cell divides, an exact copy of DNA must be created prior to cell division. Any errors represent genetic mutations.
2.Helicase untwists the DNA strand, and create 'bubbles' where A-T pairs are rich.
3.SS(single strand) binding proteins stabilize the single stand of DNA.
4.Gyrase releases tension on the DNA. (The bubbles create tension at the ends of DNA)
5.RNA primase insert RNA primers as soon as the bubbles open up. This signals the Polymerase III
6. Pol. III recognizes the RNA primers and binds a complementary 'leading' strand of DNA nucleotides at the 3' end of the RNA primer.
7. The 'lagging' strands begin to form as the bubble opens up more. They also grow from 5' to 3' and are called okazaki fragments. Pol III is also what initiated the lagging strands.
8.DNA Polymerase I replaces RNA primers with DNA. It also functions as a proof-reader to insure there aren't any mistakes.
9. Ligase inserts phosphate into any remaining gaps in the sugar-phosphate backbone
10.Each of the two new strands of DNA are composed of one new and one old chain of nucleotides.
* 1-5 = Initiation
* 6-7 = Elongation
* 8-9 = Termination
see animation: http://www.johnkyrk.com/DNAreplication.html
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