What Are the Different Types of Chromosome Disorders?
Most human cells contain 46 chromosomes, or 23 pairs of homologous chromosomes. Each chromosome of the pair is the same shape and size and has the same genes in the same location. Chromosome disorders occur due to two types of alteration in the chromosomes. Chromosome disorders can be caused by an alteration in the number of chromosomes in the nucleus, or by an alteration in the structure of a chromosome.
Most human cells contain 46 chromosomes, or 23 pairs of homologous chromosomes. Each chromosome of the pair is the same shape and size and has the same genes in the same location. Chromosome disorders occur due to two types of alteration in the chromosomes. Chromosome disorders can be caused by an alteration in the number of chromosomes in the nucleus, or by an alteration in the structure of a chromosome. Sex cells, or gametes, have only 23 chromosomes. When the sex cells are produced, chromosomes separate and move to opposite ends of the cell. Sometimes a chromosome moves to the same end of the cell as its pair, instead of the opposite end. This extra chromosome is incorporated into the nucleus of the daughter cell, causing it to have an extra chromosome, a nondisjunction. As a result, one of the gamete cells will have two copies of the chromosome and the other will have none.
