Mitochondria is the "power house" where oxygen and glucose are converted into energy.
Nucleus is the control center and holds all of the cells information (DNA)
Ribosomes are the protein production centers which are then sent off to the golgi body to be packed up and sent out of the cell for use by the body.
Lysosomes are the trash receptacles and keep the unwanted clutter and garbage out of the cell.
Endoplasmic reticulum is the transportation highway by which material travels through the cell.
Cytoplasm is the jelly like filling inside of the cell that all of the organelles float around in.
Cell membrane's job is to allow materials to pass both in and out of the cell.
Chloroplasts and cell walls are found in plant cells. Chloroplasts are where energy is produced within the plant cell by obtaining energy from the sun. Cell walls act as protective barriers and maintain the cell structure.
That's pretty much it. The organelles inside of the cells each play a critical role in keeping the cell alive and producing more cells to replace old, dying ones.