From normal cell to cancer cell. All organs in your dog are composed of cells. Cells are tiny units that can only be seen with a microscope. Thousands of cells make up each organ in your dog's body. The energy for all cells is supplied by organelles called mitochondria.
All cells manufacture proteins using organelles called ribosomes.
The nucleus of every cell contains between 60,000 and 100,000 genes. Among those 60,000-plus genes are approximately 100 genes that control cell division. Think about the union of the egg and the sperm giving rise to a single cell. That single cell and the many generations of daughter cells, divide thousands of times over 63 days to produce the normal puppy with bones, muscles, skin, hair, heart, kidneys for example. Over the next several weeks to months those generations of cells composing the puppy must divide thousands of more times in order for the puppy to grow into the adult dog.