DNA molecules, or deoxyribonucleic acid molecules, are the unique molecules which possess the ability of replicating themselves in a process referred to as DNA replication. It is one of the most important mechanisms in life cells. The complex process of DNA replication involves various biochemical reactions, enzymes, specialized proteins, etc. Before we move on to the actual working process, let's have a brief look at DNA replication.
DNA replication is a process wherein copies of DNA molecules are produced within the cell nucleus. This replication process is vital because it facilitates the transfer of genetic information from one generation to another. DNA possesses the genetic information for the cell, and DNA replication process just helps in duplicating this information, so that the information transfer continues from generation to generation. The process has the ability to produce exact replicas of the said genetic material. So how does the entire process take place?
What is the DNA Replication Process?
Like all other cellular activities in living organisms, even DNA replication process requires specialized proteins. As one of the very first DNA replication process steps, helicase, a specialized protein in the cells, facilitates the splitting of the two strands of DNA which make up the double helix. Often found in a coiled state and being highly stable, it is a bit difficult to split the DNA double helix. The splitting part is facilitated by DNA gyrases, which relaxes and uncoil the DNA molecule. While this uncoiling is being carried out by DNA gyrases, another enzyme starts unzipping the molecule, by breaking the hydrogen bonds between the base pairs.
This is followed by binding between a molecule of DNA polymerase to one of the split strands of DNA. The free nucleotides in the nucleus pairs with the matching bases of the split strands. These nucleotides are eventually joined together in order to form a new complementary strand of DNA. A single-strand binding proteins helps in binding the separated strands and facilitates DNA replication. This results in producing two copies of the DNA molecule, each featuring one new strand and one strand from the original molecule. The replication process is semi-conservative, as half part of each molecule is new, while the other half is conserved from the original DNA molecule.
Replication Control Mechanism
Basically, there are two DNA replication control mechanisms - one positive and one negative. Each replication site, referred to as 'origins', has to be bound by a set of proteins to facilitate the initiation of DNA replication. This set of proteins, referred to as Origin Recognition Complex, remains attached to the DNA molecules throughout the entire process of replication. Another set of proteins, referred to as licensing factors, is also required for initiation of replication. When the replication process is complete, these proteins are destructed in order to prevent further replication cycles.
This was the basic information about the replication process of DNA in the cells of various living organisms. DNA replication process is undoubtedly a complex process, which requires deep understanding about various scientific concepts and DNA research. To make it more simple, in a DNA replication process, two complementary strands forming a DNA molecule are separated and used as templates to produce new strands by nucleotides combining to their complementary bases.