Dna replication steps
Step 8
An enzyme called DNA Ligase seals up the sequence into 2 continuous double strands.
Step 4
An enzyme called PRIMASE puts an RNA primer at the beginning of the replication
Step 6
DNA polymerase binds to the LEADING strand and then "walks" along it, elongating it, adding new complimentary nucleotide bases (A,C,G,T ) to the DNA strand at the 3' end going in the 5' to 3' direction.
Dna replication:
DNA replication is the process by which DNA makes a copy of itself during cell division. This happens at the "S" phase of the cell cycle. DNA is a double helix, one strand going 5' to 3'(leading) and the other going 3' to 5'(lagging).
Step 1
Helicase opens up the two strands of the double helix.
Step 5
One strand is oriented in the 3' to 5' direction toward the replication fork this is called the LEADING strand( the new strand will go 5' to 3', DNA polymerase can ONLY go 5' to 3' SEE STEP 6). The other strand is orientated in the 5' to 3' direction away from the replication fork this is called the LAGGING strand ( the new strand has to go 3' to 5' and this can not happen so it goes 5' to 3' in small fragments, SEE STEP 7). Due to their different orientations the 2 strands are replicated differently.
Step 2
Single strand binding proteins keep the 2 strands open
Step 7
The LAGGING strand goes 5' to 3' in fragments backwards. Each fragment needs a primer. These are called Okazaki fragments. Once several Okazaki fragments have formed they need to join together. An enzyme kicks the primers out and fills the fragment gaps.
Final result of DNA replication
The result of DNA replication is two DNA molecules consisting of one new and one old chain of nucleotides. This is why DNA replication is described as semi-conservative, half of the chain is part of the original DNA molecule, half is brand new. DNA automatically winds up into a double helix
Step 3
Topoisomerase unwinds the strands. Keeping them from twisting. The separation of the two strands makes a Y shape called a replication fork. The two separate strands act as templates for making new strands of DNA.
