The living cells of every organism constantly use energy to survive and grow. Cells break down complex carbohydrates into simple sugars that the cell can use for energy. Muscle cells may consumer energy to build long muscle proteins from small amino acid molecules.
Cells need to divide for your body to grow and for body tissue such as skin to continuously renew itself. When a cell divides, the outer membrane increasingly pinches inward until the new cells that are forming separate from each other. This process typically produces two new (daughter) cells from one (parent) cell.