122 Introduction
![Electron micrograph shows a long, thin chromosome that has a banding pattern.](https://louis.pressbooks.pub/app/uploads/sites/26/2022/09/General-Biology-I-Lecture-Lab-1657046460_Page_617_Image_0001-1024x421.jpg)
The gene is the physical unit of inheritance, and genes are arranged in a linear order on chromosomes. Chromosome behavior and interaction during meiosis explain, at a cellular level, inheritance patterns that we observe in populations. Genetic disorders involving alterations in chromosome number or structure may have dramatic effects and can prevent a fertilized egg from developing.