Chromosone Abnormalities

Chromosomal Abnormalities

Chromosomes are tiny like structures in the nucleus of the cell. They contain an estimated 30,000 to 35,000 human gene pairs that determine traits. A gene is a sequence of nucleotides that provides cells with the instructions for the synthesis of proteins. The entire set of genes in an organism’s DNA is called a genome. By controlling the proteins produced by a cell, genes influence how tissues and organs appear both phenotypically and geneotypically. These inherited appearances are called traits. We inherit traits from our parents by virtue of DNA contained in our cells, like eye and hair color as well as direct the growth and development of every part of our physical and biochemical systems. Each person normally has 23 pairs of chromosome 46 in all. We normally inherit one set of chromosomes pair from our mother and the other set from our father.

In human sexual reproduction, two distinct gametes fuse to form a zygote. Gametes are reproductive cells produced by a tube of cell division called meiosis. They contain only one set of chromosomes and are said to be haploid. The largest Chromosome is chromosome 1. Chromosome pairs 1 through 22 are known as autosomes, while chromosomes X and Y are known as sex chromosomes. (Human Genome project pg. 2) The sex chromosomes contain genes that influence sex traits and the development of reproductive organs, and the autosomes primarily contain genes that affect other body features related to sex. When the haploid male and female gametes unite in a process called fertilization, they form what is called a zygote. The zygote is diploid, meaning that it contains two sets of chromosomes. Scientists have numbered the chromosome pairs from 1 to 22, with the 23rd pair labeled as X’s or Y’s, depending on the structure. The first 22 pairs of chromosomes are called “autosomes”. The 23rd pair of chromosomes is known as the “sex chromosomes”, because they determine whether someone will be born male...