Cell growth refers to the increase in size and volume of all individual cells. It is genetically controlled and takes place before and between cell division. The prerequisite is the cellular metabolism, also called metabolism, where the cells process nutrient molecules.
In a living organism, cells are constantly dying. In humans, there are several hundred million cells whose loss necessitates the formation of a new cell. When the cell rebuilds, cell division occurs. To this signal cascades, messengers and hormones are necessary, which also cause cell growth.
When a single cell grows, the process is extremely complex. When growing a bacterial cell find z. For example, about two thousand chemical reactions occur at once. These include energy release processes, biosynthesis of small molecules to bind macromolecules, or polymerization reactions. During cell growth, all cellular structures are formed, including the cell walls, ribosomes or flagella.
During cell growth, each additional cell receives a complete chromosome and thus enough information about all monomers, ions, and macromolecules to allow another self-contained cell to exist.
In turn, multicellular organisms grow by replication of these self-formed cells. To propagate cells need stimuli. This can z. B. growth hormones.
Until the first division of a cell begins, cell growth always occurs. The time cycle of cell growth depends on genetic factors and the environment. The functions of the cells and activity of the genes are controlled by genetic circuits and also influence the growth effects.
Different speeds of cell growth can, for. As in microorganisms cause certain processes run more slowly. At the same time, a natural selection takes place, which favors cells that grow faster than others.
Cell growth is also differentiated once again into the cycle that takes place in the organism, and in the creation of cell cultures.
For example, while bacteria can re-divide after just twenty minutes, the time span of a human cell and its division is just over ten hours.
The growth of a cell is calculated in the ratio of surface area to volume. Due to this ratio, the cell soon no longer has enough surface to eliminate enough pollutants and absorb nutrients. Therefore, their growth is limited, both in unicellular organisms and in the development of multicellular organisms.
Cell growth occurs conditionally in the body, but is also operated as a cell culture. In this regard, cells are replicated and reused at a particular stage, e.g. For example, for various experiments on the study of diseases.
A single cell has an individual cell age, which begins after mitosis and at the next division reaches a maximum value that corresponds to the doubling time. The division of one into two, two into four cells, and so on, is called exponential growth.
For cell growth, certain nutrients and minerals are important, including potassium. This regulates cell growth, which in turn maintains the balance of acids and bases in the body and the release of hormones.
Basically, cells produce proteins that regulate cell growth and also affect the genes. So the cell growth also determines the better evaluation of the genes.
Changes in a cell affect the concentration of proteins formed. In fast-growing cells, there are more polymerases that allow transcription of genes. However, the fact that the activity of genes depends on cell growth makes it difficult to measure genetic circuits. The measures that characterize an activity of genes depend on the protein concentration and the growth rate. The growth rate is understood to mean the increase in size over a certain period of time. It is calculated by the growth factor.
Cell growth is of particular interest in oncology, whose research focuses on the growth of cancer cells. The number of cells plays an important role in addition to cell growth.
If the genome of a cell is disturbed, it can change morbidly. In a small number of such cells, the body's immune system reacts with destruction or renewal. It is only when cells of this species grow and divide uncontrollably that benign or malignant growths called tumors form.
In a malignant tumor, the tissue limit is soon exceeded by growth. The surrounding tissue is destroyed and new tumors are formed. The cancer cells behave like normal cells in this process. They do not know when to stop sharing or dying. Likewise, they do not stick together so they can separate and migrate from their cell structure. In this way, they can then continue to grow elsewhere. This is then a metastasis.
In turn, as the cells continue to grow, they soon form their own blood vessels to produce oxygen, hormones, and glucose. As a result, the tumor can then penetrate into surrounding tissue.