genetics

Genetics (from the "Gen", which comes from the Greek word γένος and means "descent") is a discipline of biology is the science of heredity and variation in living organisms. The fact that living things inherit their parents' character has been used since prehistoric times to improve crops and animals through selective breeding. However, the modern science of genetics, which aims to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century. Although he did not know the physical basis of heredity, Mendel observed that organisms inherit characteristics of separately-these basic units of inheritance are now called genes. Genes are regions of DNA, a molecule composed of a chain of four different types of nucleotides-the sequence of these nucleotides is the genetic information organisms inherit. DNA exists naturally as a double-stranded, ie, two chains in which nucleotides in a chain complement each other. Each string can make a template for the creation of a new complementary strand-this is the method for creating physical copies of genes can be inherited. The nucleotide sequence of a gene is translated by the cells to produce a string of amino acids, creating proteins-the order of amino acids in a protein corresponds to the order of the nucleotides of the gene. This is called the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape, this structure is responsible, in turn, the functioning of the protein. Proteins perform most functions that cells need to live. A change in the DNA of a gene can change the amino acids in a protein, changing its form and function, which can have a dramatic effect on the cell and the organism as a whole. Two other factors that can change the shape of the protein are pH and temperature. Although genetics plays a significant role in the appearance and behavior of organisms is the combination of genetics with the experiences of the body that determines the outcome. For example, while genes play a role in determining a person's height, nutrition and health of this person during childhood also play an important role. The genome is the totality of genetic information has a particular organism. Generally, speaking of eukaryotic genome beings we refer only to the DNA in the nucleus, organized into chromosomes. But we must not forget that the mitochondria contain genes (see mitochondrial genome). The term was coined in 1920 by Hans Winkler, Professor of Botany at the University of Hamburg, Germany, as an acronym of the words gene and Chromosoma. [1]
The term indicates that a diploid organism has two copies of the genome in their cells, due to the presence of pairs of homologous chromosomes. The genome does not analyze the genetic diversity or polymorphism of the genes of a species. For example, in the human genome sequence in principle could be determined with only half the DNA of a cell of an individual. To find a particular variation or diseases requires comparisons between individuals.