DNA Replication

• When DNA is replicating, each original DNA strand serves as a template for the nucleotides to form a new complimentary strand.

• DNA Replication is a semi-conservative replication which means that when a double helix DNA replicates, each of the new formed daughter DNA will have one old strand and one newly made strand.
• DNA strand opens up at different locations on one DNA and form replication bubbles at each site with 2 replication fork at each end of the bubble.
• The strands in the double helix DNA are anti-parallel, means they run in opposite directions (one runs 5'-->3' direction, the other one runs 3'-->5' direction).
• A new strand of DNA can only elongate in the 5' --> 3' direction.

DNA REPLICATION PROCESS:

1. DNA HELICASE untwist and separates the template DNA strand
2. DNA GYRASE ( type II topoisomerase, bacterial enzyme ) massages the DNA and release tension from untwisting the double helix
3. SINGLE-STRAND BINDING PROTEINS stabilize the single strand DNA that just been untwisted from the double helix
4. DNA PRIMASE, an RNA polymerase, creates primer which signal the DNA polymerase III to elongate
5. DNA POLYMERASE III recognize the RNA primers then grab nucleotides to elongate to make complementary DNA strand
6. One of the new DNA can grow continuously, only needing one primer which is called the LEADING STRAND, growing towards the replication fork  
7. On the opposite of the leading strand in the same fork is always the strand called the LAGGING STRAND, it's made out of many RNA primers connected to many OKAZAKI FRAGMENT growing in the direction of DNA 5'-->3'
8. DNA POLYMERASE I then replace the RNA primers with DNA
9. DNA LIGASE close up all the gaps like glue between each okazaki fragment that's been created during the replication