Somatal Cell Reproduction

Plato having defined man to be a two-legged animal without feathers, Diogenes plucked a cock and brought it to the Academy, and said, This is Plato s man. On which acconnt this addition was made to the definition, with broad flat nails . 

There is another common form of asexual reproduction that is clearly important to all multicellular organisms, and that is reproduction of somatal (or body) cells. These cells do not form gametes (or germ cells), and die when the organism dies. However, they reproduce in order to support growth or heal wounds. 

Somatal cell reproduction does not happen without interaction from other cells and tissues. Growth factors are proteins released by certain body cells that stimulate other cells to divide. Thus we find that platelet-derived growth factor (PDGF) is made by blood cells called platelets in response to a wound. Connective tissue cells called fibroblasts are stimulated to divide by PDGE The result is that the wound begins to heal (Campbell et al., 1999). 

There are many other growth factors present in BU, and they regulate growth of cells, some quite distant from the emanating tissues. 

Density-dependent inhibition is a term describing the phenomenon in which crowded cells stop dividing (Campbell et al., 1999). When cells divide to the point that they touch each other and fill the available space, they automatically stop dividing. When cells die and cause a hole to form, adjacent cells begin to divide until they again fill the space. This occurrence is apparently due to inadequate amounts of nutrients and growth factors when the cells are crowded (Campbell et al., 1999). 

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Somatic cells All the body cells except the reproductive (germ) cells. [NIH]... 

Cells can be divided into germ cells and somatic cells. Germ cells are reproductive cells, for example, ova or sperm. Germ cells contain genetic characteristics that are passed on to the next generation. Somatic cells do not contribute their genes to future generations they are the tissue cells such as nerve cells and muscle cells. 

Telomerase is an enzyme in eukaryotes used to maintain the telomeres. It contains a short RNA template complementary to the DNA telomere sequence, as well as telomerase reverse transcriptase activity (hTRT). Telomerase is thus able to replace telomere sequences that would otherwise be lost during replication. Normally telomerase activity is present only in embryonic cells, germ (reproductive) cells, and stem cells, but not in somatic cells. 

Somatic cells—All cells in the body, except the germ (reproductive) cells, that can divide to produce more cells like itself. 

The nuclei of eukaryotic cells contain multiply coiled DNA bound with proteins in bodies called chromosomes. The number of chromosomes varies with the organism. Humans have 46 chromosomes in their body cells (somatic cells) and 23 chromosomes in each germ cell, the eggs and sperm that fuse to initiate sexual reproduction. During cell division, each chromosome is duplicated and the DNA in it is said to be replicated. The production of duplicates of a molecule as complicated as DNA has the potential to go wrong and is a common mode of action of toxic substances. Uncontrolled cell duplication is another problem that can be caused by toxic substances and can result in the growth of cancerous tissue. This condition can be caused by exposure to some kinds of toxicants. 

The purpose of cell division is to provide growth and repair in body (somatic) cells and to replenish or create sex cells for reproduction. There are two forms of cell division. Mitosis is the division of somatic cells and meiosis is the division of sex cells (eggs and sperm). 

Nevertheless, the question can be answered. An organism, such as a chicken, is composed of many cells, each with its own DNA. The DNA in most of these cells is identical to the DNA in all the other cells. The exceptions are the reproductive cells (gametes) that have only one-half the DNA complement of the somatic cells, and damaged somatic cells that may have DNA mutations caused by physical or chemical exposure. Some of these damaged cells may grow uncontrollably, forming a cancer, whereas others may not. In any case, the chicken still r ains a chicken, no matter how many cells have DNA mutations. 

For each somatal cell division, an equal copy of genetic material is passed from the mother cell to the daughters. This complete genetic reproduction comes about through the process of mitosis. During mitosis, eukaryotic cells duplicate both sets of chromosomes before dividing. 

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