You can click to find out more about cell division . Nuclei also have a nucleolius . The nucleus and ribosomes work together in the cell to synthesise proteins. You can click to find out more about protein synthesis . Mitochondria Mitochondria are large organelles which are shaped a bit like fat sausages.
Most cells contain many mitochondria.
Mitochondria are sometimes called the 'power stations' of the cell because they burn up food molecules, in the presence of oxygen, to release energy in a process called aerobic respiration . The inner membrane of the mitochondria is folded into cristae which give a large surface area for attachment of some of the enzymes involved in respiration. All eukaryotic cells contain endoplasmic reticulum. The ER of a cell often takes up more than a tenth of the total cell volume. The membrane structure of both are identical, but rough ER has lots of attached ribosomes and so looks 'spotty'.