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Genetic Mutations

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In genetics, mutation may be small scale (affecting the nucleotide sequence of a gene) or large scale (involving a change in the chromosome). It may arise from faulty deletions, insertions, or exchanges of nucleotides in the genetic material, as caused by exposure to ultraviolet or ionizing radiation, chemical mutagens, viruses, etc. Such a change may result in the creation of a new character or trait. Somatic mutations occur in non-reproductive cells and won't be passed onto offspring. It is recognized that mutations that occur in the body or in somatic cells have no effect on an organism. Most mutations are recognized as 'foreign' by the organism's immune system and are subsequently destroyed. ...read more.


Melanoma is a cancer which usually starts in the skin, either in a mole or in normal-looking skin. As the mutation took place in a somatic cell the subsequent cancer will not be passed on genetically to the ensuing generation. Most mutations are harmful to the organism concerned. However, beneficial mutations to occur; though they are very rare and they may give a selective advantage to an organism. A mutation that occurs in a germinal cell affects the gametes produced by the organism. In most cases, such mutations wouldn't even be noticed by the individual. However, these mutations, in contrast to the somatic mutations, will be passed on to the next generation, because they occur in the cells that could potentially form a zygote with another gamete. ...read more.


Mendel also studied flower colour in peas, of which there were two distinct phenotypes, purple and white. These are caused by two different alleles of a single gene for color: the purple allele stands for the ability to make purple pigment, and the white allele stands for a lack of ability to form purple pigment, resulting in whiteness. Indeed in general it is often found that contrasting phenotypes are determined by different alleles of a single gene, as Mendel found for petal color. The specific set of alleles carried by an individual is called the genotype, which is the hereditary underpinning of the phenotype. Mendle's research highlighted the colossal differnces a solitary allele can have on the phenotype of an organism; and how such a slight disparity can have extensive effects i.e. colour or height of the organism. ...read more.

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