In the former case, it's called a trisomy, in the latter case, it's called anosomy. So a monosomic cell is a cell that lacks a chromosome, while a trisomic cell is a cell that has an extra copy of a chromosome. Now, we said that anuploid is commonly a result of something called nondisjunction that can take place either in mitosis or meiosis. So now we're going to focus on other types of chromosomal abnormalities that can arise due to different types of conditions. For example, excessive exposure to X ray. So if the cells of our body, for example, are exposed to X ray radiation, then what can happen is a segment of the chromosome can actually break off.