- Helicase: The enzyme splits and unwinds the 2-strnaded DNA molecules.
- DNA Polymerase III : Extends RNA primer with short length of complementary DNA.
- RNA Polymerase: Synthesizes a short RNA primer which is later removed.
- DNA Polymerase I: Digests RNA primer and replaces it with DNA.
- DNA Ligase: Joins neighbouring fragments together into longer strands.
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Leading strand
•Leading strand is the new strand that grows continuously toward the replication fork.
• The new strand is 5’–>3’ direction. It is also complementary to 3’–>5’ parent strand.
•DNA polymerase reads the parent strand in 3’ to 5’ direction, while building the new strand in opposite (5’–>3’) direction.
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Lagging strand
Okazaki Fragment: The lagging strand is formed in fragments, between 1000 and 2000 nucleotides long – called Okazaki fragments.
•Since new nucleotides can only be added at the 3’end, each new half-strand is synthesized in the 5’–>3’ direction.
•At the 5’end of the old strand, the new strand is synthesized in separate bits called Okazaki fragments. These grow addition at their 3’ends and are then joined up by DNA ligase.
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You should be able to explain the steps involved in DNA Replication & role of the enzymes in DNA replication.
To help you with the understanding of this concept watch this Youtube video: http://www.youtube.com/watch?v=teV62zrm2P0