Genetic Disorder

Genetic Disorders

There are millions of people in the world today and not one person is the same. Even identical twins may look similar but have a distinguish trait to tell them apart. Just from a quick observation you can always tell that a child may look more like one parent but after close observation and understanding you will come to realize that there is more than the outside looks that makes a person who they really are. In this paper, I will try to briefly explain the role genetics play in human development, how genes of two parents determine the physical makeup of a child, and how certain abnormalities may cause chromosomal disorders such as Fragile X and Tay- Sachs disease.

Genes can sometimes be difficult to understand, they contain conflicting information and in most cases one gene will win the battle over dominance. When a sperm or ovum is formed, the number of chromosomes may divide unevenly, causing the organism to have more or less than normal 23 chromosomes. When one of these abnormal cells joins with a normal cell, the resulting zygote will have an uneven number of chromosomes. Researchers suggest that as many as half of all zygotes that form have more or less than 23 chromosomes, but most of these are spontaneously aborted and never develop into a full-term baby. (Kirk, M)

The entire genetic code of a human is determined by the unique combination of a mother's single ovum (egg) and a father's single sperm. These cells are the sex or reproductive cells. The one cell that is formed after the sperm and egg unite contains instructions on replication that will eventually turn one cell into trillions with each of which contains the identical genetic code of the original. (Kirk, M)

Within each cell are chromosomes, which store the genetic information. The ovum and the sperm first carry the genetic information that will direct development. These sex cells are the only cells in the body that contain 23 chromosomes. (Interestingly, ova are the largest cells in the human body and sperm are the smallest.) When the two sets of 23 chromosomes unite, they form 46 chromosomes (23 pairs). (Mossler, R) Half of each pair is from the father and half is from the mother. Each set of chromosomes contains deoxyribonucleic acid (DNA), a molecule that contains instructions on how to build those trillions of cells. (Mossler, R)

Cells contain a central structure called the nucleus, which holds the chromosomes. Along the short segments of DNA are genes, which specifically carry hereditary information and are therefore located at specific sites on the chromosome. (Mossler, R)One way to look at the relationship between the terms is by this analogy: Chromosomes are like books, DNA is the words, and genes are the letters. Each chromosome carries hundreds or thousands of genes. The complete set of instructions for making a human would be like having an entire library. (Mossler,