Cells produce offspring by the process of mitosis. First the parent cell DNA is replicated so there are two identical copies. Fibers pull the two sets of chromosomes to opposites ends of the cell, and then the cellular membrane pinches together in the center to make two identical cells. The director of the MIT Community Outreach and Education Program developed a series of LEGO models to help kids learn about biology, including this mitosis animation. These models, joined together under Sciene Builders, Inc. were at one time available for sale through LEGO Education, though it doesn't look like they are available any more. Don't worry, though. These are pretty simple constructions, so you could easily build your own based on their inspiration. If you need LEGO bricks, check out BrickLink.