Cell division

All living things, including you, are made up of cells. Find out how cells divide through mitosis and meiosis, how the cell cycle is controlled, and how problems in cell cycle control can lead to cancer.
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One of the major goals of dividing cells is to split up their DNA as perfectly as possible. (Incorrect division of DNA = chance of a nonfunctional cell, or even cancer!) Learn how DNA combines with proteins to form chromosomes, why different types of cells have different chromosome numbers, and what the parts of a chromosome are.

Imagine scraping your elbow. Ouch! In addition to being a little uncomfortable, you just lost a bunch of skin cells. How does your body make new cells to replace ones that are damaged or lost? Some of the remaining cells can divide (undergo mitosis) to produce new, healthy replacement cells. Learn more about mitosis and how cells divide.

Normal human body cells have two complete sets of chromosomes, while sperm and egg cells have just one set each. How, then, does a normal body cell give rise to sperm or eggs? The answer lies in a two-step division process called meiosis. Learn more about meiosis and how it contributes to genetic variation in humans (and other sexually reproducing organisms).

Cells in your body are dividing all the time. If they're healthy cells, they divide in a carefully controlled way, proceeding with division only when conditions are right. Cancer cells, on the other hand, divide in an uncontrolled way. Learn more about cell cycle control, cancer cells, and stem cells.