Intro -The concept of gene has been the subject of several hundred years of work to establish the basis of heredity, but there is no simple answer to the question of what exactly a gene is. Genes have a variety of different functions. A gene is a DNA sequence that carries information representing a protein. The DNA sequence can be identified as a continuous stretch of nucleotides and chromosomes. Genes are made of DNA and serve as instructions for making the molecule called proteins. Medal's definition law states that when producing two gametes through reproduction, the two copies of each hereditary factor separate so that the offspring acquire one factor from each parent. Mendal has three laws of gene types, inheritance, dominance and segregation, Mendal's second law summarizes the independent assortment of different genes, for example when a plant is dominant for two different characteristics is crossed with a parent recessive for both, for example if a human or plant has recessive traits or characteristics, meaning they are hidden but derived from their parents, then the recessive shows up as dominant when that human or plant reproduces their offspring . Structure of a Gene - To understand a gene, we must first understand the importance of chromosomes in cells. Chromosomes are responsible for inheritance. Early experiments showed that a typical cell consists of a dense nucleus separated by a membrane from the surrounding less dense cytoplasm within the nucleus, the granular region of chromatin. Chromosomes can be seen in most cells during the process of cell division. They are threadlike structures of nucleic acids and proteins found in the nucleus of most living cells carrying genetic elements...... middle of paper ...... n like unstable alleles. Examples of this type of disease are Huntington's disease and the myotonic form of muscular dystrophy. The process of gene expression occurs throughout the life of any organism, starting from the beginning, when an organism develops first as a zygote and then as an embryo. . Genes activate to regulate this process, cells start out exactly the same but this process quickly changes their characteristics, cells that have the ability to transform into any type of tissue are totipotent. Cells receive instructions from their DNA to turn into certain tissue types, such as skin and bone, once the tissue type has been decided, some genes in the cells become active and others are permanently turned off. This is because gene expression is highly tissue specific, meaning that certain genes are only active in certain tissues or at a particular stage of their development..