In the heart of the cell lies the nucleus, surrounded by its own separate membrane, where the chromosomes are stored. In between the nucleus and outer membrane is the cytoplasm, where the cell's metabolic work is done. These enzymes, called ribosomes, translate the mRNA code into proteins of all sorts. These proteins are then passed along to another multi-layered organelle called the Golgi apparatus, which folds them up into the right shapes and sends them off to their proper destinations in the cell. Mitochondria are very common organelles, with enzymes inside that break down sugar and fat to produce ATP, an energy-carrying molecule that fuels all the reactions in the cell.
Mitochondria are unique in having their own sets of DNA, separate from the nucleus .
Other important parts of the cytoplasm are the lysosomes, which break down and recycle proteins and fats, and the microtubules, which are proteins that are both a girder system, giving the cell structure, and a sort of internal railroad system for routing proteins around the cell. It's still not clear what goes wrong in cases like Maureen Ott, where the cytoplasm in her eggs was granular and lumpy. Maybe it's the microtubules not providing proper structure, or perhaps the ER isn't working right. Whatever it is, a shot of donor cytoplasm, containing all the enzymes and organelles mentioned above, provides the jump start that makes conception possible.