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Somatic cell

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Title: Somatic cell  
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Subject: Germ cell, Partial cloning, Barr body, Somatic fusion, 1990s
Collection: Cells, Cloning, Developmental Biology, Genetics
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Somatic cell

A somatic (Greek: σὠμα/soma = body) or vegetative cell is any gamete, germ cell, gametocyte or undifferentiated stem cell.[1]

In contrast, gametes are cells that fuse during spermatozoa and ova which fuse during fertilization to produce a cell called a zygote, which divides and differentiates into the cells of an embryo. There are approximately 220 types of somatic cells in the human body.[1]

The word "somatic" is derived from the Greek word sōma, meaning "body".

Contents

  • Evolution 1
  • Genetics and chromosome content 2
  • Cloning 3
  • Somatic cell Modifications 4
  • References 5
  • See also 6

Evolution

As multicellularity evolved many times, sterile somatic cells did too. The evolution of an immortal germline producing specialized somatic cells involved the emergence of mortality, and can be viewed in its simplest version in volvocine algae.[2] Those species with a separation between sterile somatic cells and a germ line are called Weismannists. However, Weismannist development is relatively rare (e.g., vertebrates, arthropods, Volvox), as great part of species have the capacity for somatic embryogenesis (e.g., land plants, most algae, many invertebrates).[3][4]

Genetics and chromosome content

Like all cells, somatic cells contain zygote. Due to the fusion of the two gametes, a human zygote contains 46 chromosomes (i.e. 23 pairs).

However, a large number of species have the chromosomes in their somatic cells arranged in fours ("tetraploid") or even sixes ("hexaploid"). Thus, they can have diploid or even triploid germline cells. An example of this is the modern cultivated species of wheat, Triticum aestivum L., a hexaploid species whose somatic cells contain six copies of every chromatid.

Cloning

In recent years, the technique of ovum of the same species which has had its own genetic material removed. The ovum now no longer needs to be fertilized, because it contains the correct amount of genetic material (a diploid number of chromosomes). In theory, the ovum can be implanted into the uterus of a same-species animal and allowed to develop. The resulting animal will be a nearly genetically identical clone to the animal from which the nucleus was taken. The only difference is caused by any mitochondrial DNA that is retained in the ovum, which is different from the cell that donated the nucleus. In practice, this technique has so far been problematic, although there have been a few high profile successes, such as Dolly the Sheep and, more recently, Snuppy, the first cloned dog.

Somatic cell Modifications

Development of Biotechnology has allowed for the genetic manipulation of somatic cells.This biotechnology deals with some ethical controversy in Human genetic engineering.

References

  1. ^ a b Campbell, Neil A.; Reece, Jane B.; Urry, Lisa A.; Cain, Michael L.; Wasserman, Steven A.; Minorsky, Peter V.; Jackson, Robert B. (2009). Biology (9th ed.). p. 229.  
  2. ^ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098969/
  3. ^ Ridley M (2004) Evolution, 3rd edition. Blackwell Publishing, p. 29-297.
  4. ^ Niklas, K. J. (2014) The evolutionary-developmental origins of multicellularity.

See also

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