What is the interphase, or the most important part of the cell cycle

What is Interphase? The term originated from the Latin word "inter", translates as "between", and the Greek "phase" - period. This is an important period during which the cell grows and stores nutrients, preparing for the next division. Interphase occupies the most part of the entire cell cycle, up to 90% of the entire life of the cell falls on it.

What is Interphase

As a rule, the main part of the components of cells grows over the length of the whole phase, therefore it is rather difficult to single out some separate stages in it. Nevertheless, biologists divided the interphase into three parts, focusing on the time of replication of deoxyribonucleic acid (DNA) in the nucleus of the cell.

Interphase periods: phase G (1), phase S, phase G (2). The presynthetic period (G1), whose name originated from the English gap, translated as an "interval", begins immediately after division. This is a very long period, lasting from ten hours to several days. It is during this time that there is accumulation of substances and preparation for the doubling of the genetic material: the synthesis of RNA begins, the necessary proteins are formed.

What is the interphase in its last period? In the presynthetic phase, the number of ribosomes increases, the surface area of the rough endoplasmic reticulum increases, and new mitochondria appear. The cell, consuming a lot of energy, is growing rapidly.

Differentiated cells, no longer able to divide, are in a rest phase called G0.

Main Interphase Period

Regardless of what processes occur in the cell in the interphase, each of the subphases is important for general preparation for mitosis. However, the synthetic period can be called a turning point, because during it chromosomes are doubled and direct preparation for division begins. RNA continues to be synthesized, but immediately connects to the proteins of the chromosomes, beginning DNA replication.

Interphase cells in this part lasts from six to ten hours. As a result, each of the chromosomes doubles and already consists of a pair of sister chromatids, which then disperse at the poles of the spindle of division. In the synthetic phase centrioles are doubled, if they are, of course, present in the cell. During this period, the chromosome can be seen in a microscope.

The third period

Genetically, chromatids are exactly the same, because one of them is maternal, and the second is replicated with matrix RNA.

As soon as the full duplication of all genetic material has occurred, the post-synthetic period preceding the division begins. Then follows the formation of microtubules, from which the fission spindle will subsequently form, and the chromatids will disperse at the poles. Also energy is stored, because during the period of mitosis, the synthesis of nutrients decreases. The duration of the postsynthetic period is not high, usually lasts only a few hours.

Checkpoints

During the cell cycle, the cell must pass through unique control points-important "marks", after which it passes into another stage. If, for some reason, the cell could not pass the control point, the whole cell cycle freezes, and the next phase does not begin until the problems that prevented it from passing through the checkpoint have been removed.

There are four main points, most of which are just in the interphase. The first control point of the cell passes in the presynthetic phase, when the intactness of the DNA is checked. If all is true, then the synthetic period begins. In it, the point of verification is the verification of accuracy in DNA replication. The control point in the post-synthetical phase is the check of damages or omissions at the two preceding points. In this phase, it is also checked how fully replication and cells have taken place. Those who do not pass this test are not allowed to mitosis.

Problems in interphase

Violation of the normal cell cycle can lead not only to malfunctions in mitosis, but also to the formation of solid tumors. Moreover, this is one of the main reasons for their appearance. The normal course of each phase, however short, determines the successful completion of subsequent stages and the absence of malfunctions. Tumor cells have changes in the check points of the cell cycle.

For example, in a cell with damaged DNA, the synthetic period of the interphase does not occur. There are mutations that result in loss or changes in the genes of the p53 protein. Cells do not block cell cycle, and mitosis begins prematurely. The result of such problems is a large number of mutant cells, most of which are not viable. However, those that can function, give rise to malignant cells, which can be divided very quickly by reducing or missing the rest phase. The characteristic of the interphase contributes to the fact that malignant tumors consisting of mutant cells have the ability to divide so rapidly.

Interphase duration

Here are a few examples of how much longer the cell lives in the interphase period, compared with mitosis. In the epithelium of the small intestine of ordinary mice, the "rest phase" takes at least twelve hours, and the mitosis itself lasts from 30 minutes to an hour. Cells that make up the root of horse beans are divided every 25 hours, and the phase M (mitosis) lasts about half an hour.

What is the interphase for the life of a cell? This is an important period, without which it would be impossible not only for mitosis, but for cellular life in general.