MicroBiology

Have you ever wondered that how life continues in human beings? How do we all human beings share the same characteristic features? Yes, DNA is the answer to all your questions. The most significant mechanism for all the life cells that plays an important role in producing off springs is the DNA replication. DNA replication is the process that duplicates the DNA of a cell.

Each cell in our body consists of one or more than one DNA polymer molecules. These molecules need to be duplicated, so that the process of cell duplication takes place. This is what we call as DNA replication. In living organisms, the formation of DNA takes place in two strands. Each strand contains units of nucleotides. These two strands of DNA appear like two chains forming the DNA Double Helix. The process of DNA replication opens up the Double Helix and separates them into two strands. These two strands are then copied, and the result is that two new molecules of DNA are formed.

Steps involved in the replication of DNA

The first step in the DNA replication process is the breaking of the hydrogen bonds. This is the starting point where the two strands are unwounded. The enzyme that brings about the splitting between the two strands is Helicase and the structure thus created is referred as “Replication Fork”. The next step in the process is binding the RNA primase. The RNA nucleotides are attracted by the RNA Primase that gets bound to the DNA nucleotides because of the presence of hydrogen bonds between the bases. The RNA Primers are very vital for the DNA polymerase for binding the nucleotides, and the result is that the daughter strand is elongated because of this.

The DNA polymerase in the outer strand reads the fragments and thus, the RNA Primers are detached from there. The action of DNA polymerase closes the gaps formed by adding complimentary nucleotides, whereas the DNA Ligase closes the gaps by adding phosphates. Finally, the last step of the process is the termination. This process takes place only after the DNA polymerase reaches towards the end of the strands. DNA replication process is completed only after a repair mechanism fixes all the errors taken place during the replication process. There are enzymes such as DNA polymerase that fills up the gaps and nucleases that eliminates the improper nucleotides.

The speed of DNA replication in human beings is approximately 50 nucleotides/ second/ replication fork. It is relatively low when compared with the speed of DNA replication in bacteria’s. Nevertheless, human genome can be copied in just a few hours as a number of replication forks occur at the same time. This is also known as multiple initiation sites.

DNA replication is also performed artificially with the use of same enzymes that are used within the cell. Artificial DNA Primers and DNA Polymerases are used for initiating the synthesis of DNA at known sequences in a molecule of a template. Common laboratory method and polymerase chain reactions makes use of artificial synthesis rapidly in a cyclic form and particularly intensify the targeted fragment of DNA from the DNA pool.