DNA Replication Steps and Process

DNA replication is the basis of biological inheritance. The term DNA replication implies replicating DNA strands or making a copy of the existing DNA strand during cell division. DNA replication occurs in multiple steps with the use of multiple proteins called enzymes. The process of DNA replication is carried out with the help of enzymes called helicase. The helicase enzyme breaks down the hydrogen bond while holding the complementary bases of DNA as it is. It is important as it takes part in growth, reproduction, and creating variation in organisms. In eukaryotic organisms, the process of DNA replication occurs in the S phase of the interphase which is itself a part of the cell cycle.

DNA Replication Processes

 DNA replication processes are segregated into 3 main steps.

1. Initiation:

This is the first step of the DNA replication process. DNA is a double standard structure that is formed of 4 bases called cytosine thymine adenine guanine, hence before we start its replication we must separate the two strands individually. 

The basis reacts with each other in the following relation:

• Adenine pairs with thymine.
• Guanine pairs with cytosine.

Before we initiate the process of replication these interactions between the bases are meant to be broken. The breaking of bonds between the bases is done by an enzyme called DNA helicase. Helicase enzyme breaks down the hydrogen bond present in between the base and forms to avoid shape structure which is also referred to as the replication fork. These stunts will be used for reference to form a replica of the existing strand. DNA is a directional strand, which means both the stands show direction indicated by a 5′ and a 3′ end. The notations signify the group which is attached to the end. The phosphate group lies at the 5′ end, hydroxyl group lies at the 3′ end. Directional nature is important for DNA because replication only takes place from 5′ to 3′ orientation. At the end of the strands separation process, lagging and leading strands are formed. Both these trends are replicated by different processes because of their different directional nature. 

The leading strand is the most convenient strand for replication. Once the strands are separated a short piece of RNA also referred to as primer, binds to the 3′ end. The primer is also stated as the beginning point of replication. The primers are formed by an enzyme called DNA Primase.

2. Elongation:

This is the second step of the DNA replication process. New trends of DNA are formed by the process of elongation with the help of enzymes called DNA polymerase. Five different types of DNA polymerase are seen in human and bacterial cells. In bacterias polymerase 2 enzyme is the main replicating enzyme whereas the rest is for polymerase enzymes to help in checking defects arising in replication. The newly formed DNA stand is found to be continuous as a result of replication which proceeds from a 5′ to 3′ direction.

Now the lagging strand begins replication. It does so by binding to multiple primers where each primer is located at a gap of a few bases. The enzyme DNA polymerase adds New pieces of DNA called Okazaki fragments in between the primers. Here the process of stand formation is discontinuous.

3. Termination:

This is the third and final step of the process of DNA replication. After the discontinuous and continuous DNA strands are formed, an enzyme exonuclease removes the RNA primers located at the original strand. The RNA primers which are terminated are replaced by bases. Another part of exonuclease enzymes checks whether the bases which are formed as a replacement of RNA primer are correctly placed or not. Another enzyme DNA ligase after the discontinuous strands and joins the Okazaki fragments. 

At the end of the parents’ strand lies tell me which are repeated DNA sequences. The function is to protect the ends of chromosomes by preventing them from being used with other chromosomes present nearby. Enzyme telomerase fastens the process of telomerase synthesis. Once the process of DNA replication is complete the parent’s strands and their complementary strand coils again form a double helix structure. Aunty and two DNA molecules are replicated and formed.

Conclusion 

From the above information, it can be concluded that the replication of DNA is an important process because it plays an important role in many biological processes and it is also an important part of biological inheritance. There are three major steps involved in the process of DNA replication. The three steps are initiation elongation and termination, where first the parent DNA is separated and forms a single-stranded DNA structure, followed by replication with the help of enzymes.