Final Draft Essay 2

Types of mutations and their inheritance: Somatic and Germ line

In genetics, a gene mutation is known as a change in the DNA sequence.   A mutation can be of small or large proportions, and cause a gene to lose its function and therefore prevent the organism from working correctly (Mutations involve). It can change only a single DNA base, or a big piece of DNA sequence in a chromosome (Mutations involve).  Some mutations can be silent, having no effect on the organism’s phenotype but other s can cause great changes in the organism’s physical traits (When genes go bad). There are two ways in which gene mutations occur: it can be inherited or can develop throughout lifetime.  While somatic mutations are not inherited, are caused by mutations in the individual cells and have no effect on the overall organism’s phenotype, germ line mutations are inherited, every cell has the mutation, and has effects on the phenotype; it is evident that these two types of mutations play a key role in evolution.

Somatic mutations affect somatic cells: regular cells that make up tissues of the body.  Somatic mutations occur while a cell is undergoing regular cell division, or mitosis (Inheritance pattern).  They can be found by comparing DNA from different cells from the same individual. These mutations occur after fertilization and throughout life; therefore they cannot be inherited. There are two general categories of mutations: point and chromosomal mutations (Types and causes). Point mutations are ones that change one nucleotide either by a deletion or substitution of a nucleotide in the DNA sequence (Types and causes). Chromosomal mutations change the DNA sequence with insertions, inversions or translocations of more than nucleotide (Types and causes). Usually somatic mutations are caused by point mutations and changes can go unnoticed or silent having no effect on the phenotype.  For example, if the mutation is cancerous then the body will keep producing these cells until the person dies.  Somatic mutations can cause damages in the bladder, liver and kidney function.  Among somatic mutations the most dangerous are the ones that occur in the regulation of growth and cellular division.  Cells start reproducing without control and start forming cancerous cells (Somatic mutations).

Germ cells or sexual reproductive cells are developed either into a sperm or an egg. The process of creating reproductive cells is known as meiosis and it is in this process that germ line mutations occur (Inheritance patterns). If a germ line mutation occurs all the germ cells in the body will contain this mutation.  Most dangerous germ line mutations are the ones that interfere with the function of the organism.  Such mutations may change the way we interact with diseases, or the environment. For example, red-greed blindness (Daltonism) affects your ability to distinguish colors (When genes go bad), and type 1 diabetes is a mutation that prevents you from producing insulin and digesting sugar (Type 1 Diabetes). However, there are germ line mutations that increase your chances of getting cancer.  If an individual carries such mutation in all its cells, fewer somatic mutations are needed to change it to the cancerous state.  For example, BRCA1 mutation is known to greatly increase the chances of breast cancer (BRCA1 and BRCA2).  This explains why cancers tend to run in certain families but not in others.

Not all the mutations are the same: they are different by type, effect, mechanism, and location.  Fortunately, there is repair mechanism: cells can fix mutations, otherwise there would be too many of them.  However, not all mutations are harmful.  Some of germ line mutations are neutral, or can actually improve your body.  These mutations are rare, but they happen often enough to contribute to the variation between individuals, or serve as material for evolution of the species.  The evolutionary roles of these two types of mutations are critical but different. Evolution of development tries to control all somatic cells from deviating from the original pattern from the first embryonic cell. Therefore, the evolutionary forces are keeping somatic cells similar. On the other hand, while most of the germ line mutations are disadvantageous for the development of the organisms, there are precious few that provide positive traits that can benefit the individual and promote evolution.

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