In which cell stage does DNA replicate? The process of DNA replication is a complicated problem. It involves a series of proteins and enzymes that collectively gather nucleotides in a predestined sequence. In response to the molecular signs accepted during cell furcation, these molecules replicate DNA and synthesize 2 new strands using the available strands as templates. Each produces two, identical DNA molecules consisting of one new strand and one old DNA. Therefore, the DNA replication process is called semi-conservative.
DNA replication is the process of doubling the DNA double chain. In cells, DNA replication occurs before the DNA division. The DNA replication process is also able to be carried out in a process which is called Polymerase Chain Reaction or PCR.
The materials of DNA are molecules called nucleotides, which consists of a deoxyribose sugar, a nitrogen case attached to a sugar, and a phosphate group. There are 4 types of nucleotides molecules depending on the type of nitrogen base installed. Those 4 nucleotides are Guanosine, Adenosine, Cytidine, and Thymidine.
If you really want to know in which cell stage does DNA replicate, check these steps of the process of DNA replication in order to know the answer.
The DNA replication starts in a specific location which is called as an origin of replication, that has a particular sequence that can be acknowledged by a protein called as initiator DNA. They bind DNA molecules at the place of origin, thus loosening to assemble other proteins and enzymes essential for DNA replication. An enzyme named helicase is enlisted to the site for unwinding, which is a decomposition process, of the helix in a single groove.
The helicase releases the hydrogen bonds between base pairs, in a way which depends on the energy. This DNA area of point is now known as a replication fork, which is a structure formed when DNA replicates. After an open helix, a protein called as a single strand binding protein binds open areas and prevents them from sticking back. The process of replication then starts, then the replication fork continues in 2 opposite ways along the DNA molecule.
A new synthesis, the complementary DNA strand using the existing strand as a template carried by an enzyme known as DNA polymerase. Besides the replication, they also play an essential role in improving DNA and recombination. But DNA polymerase cannot initiate DNA synthesis independently, and requires 3 hydroxyl groups to initiate the complementary nucleotides. This is supplied by an enzyme named DNA primase which is a type of DNA-dependent RNA polymerase. This synthesizes a short stretch of RNA to the existing DNA strand.
This low section is named primary and composed of 9 to 12 nucleotides. This gives the DNA polymerase the platform needed to start copying a DNA strand. After the primer is built on both strands, DNA polymerase can extend this primer to a new DNA strand.
The DNA zipper opening is able to cause a supercoiling, which is a disturbing spiral-like formation, in the following fork area. This supercoil DNA is disclosed by a specific enzyme named topoisomerase which binds to the stretch of DNA in the front of the replication fork. This creates a cut on the DNA strand in order to ease the supercoil.
Synthesis Leading Strand
DNA polymerase can enhance new nucleotides only to the 3’ end of the available strand, and therefore can synthesize DNA in the direction of 5’ to 3’ only. But the DNA strands run in the opposite direction, and therefore DNA synthesis one strand can occur constantly. It is known as a leading strand.
Here, DNA polymerase III acknowledges 3’ OH end of RNA primary and enhances new complementary nucleotides. When the replication fork goes on, new nucleotides are enhanced regularly, resulting in a new strand.
Synthesis Lagging Strand
On the contrary strand, DNA is synthesized interrupted by producing a series of tiny fragments of new DNA in the direction of 5’ to 3’. This fragment is called the Okazaki fragment, which then joins to form a perpetual chain of nucleotides. This strand is known as a lagging strand since the process of DNA synthesis in this strand yields at a lower level.
Here, primase adds primers in some areas along the open strands. DNA polymerase III prolongs the primers by adding new nucleotides and falls when it gathers a preformed fragment. This is why it is important to free the DNA strand, then move further to the peak to start the expansion of other RNA primers. A sliding clamp keeps the DNA in place when moving through the replication process.
Although the new DNA strands synthesized RNA primers provides on the newly built strand must be displaced by DNA. This activity is carried out by the DNA polymerase I enzyme. This is specifically to eliminate RNA primers through 5’ to 3’ exonuclease activity and replace them with new deoxyribonucleotides with 5’ to 3’ DNA polymerase activity.
After the primary removal, the left strand still conceives a slit between the contiguous Okazaki fragments. The ligase enzyme identifies and clogs the gap by making a phosphodiester bond between 5 phosphates and 3 hydroxyl groups of adjacent fragments.
This DNA replication stops at a special termination site consisting of the unique nucleotide sequence. This sequence is acknowledged by a particular protein named tus that ties to the site, thus physically blockade the helicase pathway. When the helicase converge the protein, it falls along with the single strand of the closest binding protein. This is the end of the process of DNA replication.
Those are the steps of DNA replication which is able to be your information if you were wondering about in which cell stage does DNA replicate. As it is said before and you can see, the DNA replication is pretty complex and may hard to be understood. By knowing those steps, hopefully, you are able to have the answer of in which cell stage does DNA replicate