WHY DO CELLS DIVIDE ?
Every day , every hour , every second , cells are dividing . When cells divide , they make new cells . A single cell divides to make two cells and those two cells then divide to make four cells , and so forth .
Cells divide for three main reasons : 1 . To maintain tissue : cells divide to replace old or dead cells .
2 . To repair tissue : when you skin your knee , cells divide to replace damaged cells .
3 . To grow : when organisms grow , it isn ’ t because cells get larger ; organisms grow because cells divide to produce more cells - in humans , nearly two trillion cells divide every day . We all begin as a single cell , an egg . By adulthood , we are made up of an average of 37 trillion cells .