Eukaryotes are cells that have nucleus' and Prokaryote have no nucleus'. I will be writing about the Prokaryote cells.
The cell walls' main job is to protect everything inside of it, although, another very important job it has is to let things out and in as they are needed. The very outside layer of the cell wall is called the cellular membrane.
Inside the cell is the nucleus which appears dark in color under a microscope. The nucleus contains the DNA for the cell and the nucleolus. The nucleus is the sometimes called the "headquarters" of the cell because it seems to be at the central location.
Dotted all throughout the cell fluid, the Cylosol, are little Ribosomes. The Ribosomes make the proteins for the cell. They embed themselves throughout the rough endoplasmic reticlulum(E.R.), making it appear bumpy and rough. Anywhere there is not a Ribosome attached is called a smooth E.R.
When the Ribosomes are making so much protein, something has to package it. This is where the golgi body comes in. It fills a little bubble with proteins and then squeezes it out. It is then packaged in a nice little bubble and can float around until used or sent to another cell.
Source: Khan Academy Lecture