Replication in biology is an important molecular process of body cells
Nucleic acids play an important role inmaintenance of vital activity of cells of living organisms. An important representative of this group of organic compounds is DNA, which carries all the genetic information and is responsible for the manifestation of the necessary characteristics.
What is replication?
In the process of cell division, it is necessary to increasethe number of nucleic acids in the nucleus, so that there is no loss of genetic information in the process. In biology, replication is the duplication of DNA by the synthesis of new chains.
The main goal of this process is to transfer the genetic information to the daughter cells in an unchanged form without any mutations.
Enzymes and proteins of replication
Doubling a DNA molecule can be compared to anymetabolic process in a cell for which appropriate proteins are needed. Since in biology replication is an important component of cell division, accordingly, many auxiliary peptides are involved here.
- DNA polymerase is the most important reduplication enzyme,which is responsible for the synthesis of the daughter chain of deoxyribonucleic acid. In the cytoplasm of cells during the replication process, the presence of nucleic triphosphates, which bring all nucleic bases, is mandatory.
These bases are nucleic acid monomersacid, so the whole chain of the molecule is constructed from them. DNA polymerase is responsible for the assembly process in the correct order, otherwise inevitable occurrence of all kinds of mutations.
- Prymaza is a protein that is responsible forformation of a primer on the template DNA strand. This primer is also called a primer, it has the structure of RNA. For the DNA polymerase enzyme, the presence of initial monomers is important, from which further synthesis of the entire polynucleotide chain is possible. This function is performed by the primer and its corresponding enzyme.
- Helicase (Helicase) forms a replication fork, which is the discrepancy of the matrix chains by breaking the hydrogen bonds. So it is easier for polymerases to approach the molecule and start synthesis.
- Topoisomerase. If we imagine a DNA molecule in the form of a twisted rope, when the polymerase moves along the chain, a positive voltage will form due to strong twisting. This problem is solved by topoisomerase, an enzyme that breaks the chain for a short time and unfolds the whole molecule. After that the damaged site is sewn up again, and DNA does not experience tension.
- Ssb proteins, like clusters, attach to DNA strands in a replication fork to prevent the re-formation of hydrogen bonds before the end of the reduplication process.
- Ligase. The function of the enzyme is to crosslink the fragments of Ozakaki onto the lagging chain of the DNA molecule. This occurs by cutting out the primers and inserting in their place the native monomers of deoxyribonucleic acid.
In biology, replication is a complexa multistep process, which is extremely important in cell division. Therefore, the use of various proteins and enzymes is necessary for efficient and correct synthesis.
There are 3 theories that explain the DNA doubling process:
- Conservative argues that one daughter nucleic acid molecule is of a matrix nature, and the second is completely synthesized from scratch.
- The semiconservative is suggested by Watson and Crick and confirmed in 1957 in experiments on E. Coli. This theory says that both daughter DNA molecules have one old chain and one newly synthesized.
- The dispersive mechanism is based on the theory that daughter molecules have on the entire length of alternating sections, consisting of both old and new monomers.
Now a semiconservative model has been scientifically proved. What is replication at the molecular level? At the beginning of the helicase, the hydrogen bonds of the DNA molecule breaks, thus opening up both chains for the polymerase enzyme. The latter, after formation of the primers, begin the synthesis of new chains in the 5'-3 'direction.
The property of antiparallelism of DNA is the mainthe cause of formation, leading and lagging chains. On the leading chain, the DNA polymerase moves continuously, and on the lagging it forms fragments of Okaucasia, which in the future will be combined with ligase.
Features of replication
How many DNA molecules in the nucleus after replication? The process itself involves the doubling of the genetic set of the cell, so in the synthetic period of mitosis, the diploid set has twice as many DNA molecules. Such an entry is usually marked as 2n 4c.
In addition to the biological meaning of replication, scientistsfound application of the process in various fields of medicine and science. If in biology replication is a duplication of DNA, then in the laboratory, multiplication of nucleic acid molecules is used to create several thousand copies.
This method was called polymerase chain reaction (PCR). The mechanism of this process is similar to replication in vivo, therefore similar enzymes and buffer systems are used for its course.
Replication has an important biological significancefor living organisms. The transfer of genetic information in cell division is not without the doubling of DNA molecules, therefore, the coordinated work of enzymes is important at all stages.