Genetics For Dummies, 3rd Edition

Chapter 13

Chromosome Disorders: It’s All a Numbers Game

IN THIS CHAPTER

Understanding how things can go wrong with chromosomes

Learning about the more common chromosome disorders

Learning how chromosomes are examined

The study of chromosomes is, in part, the study of cells. Geneticists who specialize in cytogenetics, the genetics of the cell, often examine chromosomes as the cell divides because that’s when the chromosomes are easiest to see. Cell division is one of the most important activities that cells undergo; it’s required for normal life, and a special sort of cell division prepares sex cells for the job of reproduction. Chromosomes are copied and divvied up during cell division. Getting the right number of chromosomes in each cell as it divides is critical. Most chromosome disorders, such as Down syndrome, occur because of mistakes during meiosis (the cell division that makes sex cells).

This chapter helps you understand how and why chromosome disorders occur. You see some of the ways geneticists study the chromosome content of cells. Knowing how many chromosomes are in each cell allows scientists to decode the mysteries of inheritance, especially when the number of chromosomes ...