What is a ribosome and what does it do?

Ribosomes are composed of a large subunit and a small subunit. When these two subunits combine, they form a complete ribosome that is capable of converting genetic code found in RNA into a sequence of amino acids. The ending result is a protein structure. Under a microscope, ribosomes appear to be tiny bead-like structures. read more

When a ribosome begins to synthesize proteins that are needed in some organelles, the ribosome making this protein can become "membrane-bound". In eukaryotic cells this happens in a region of the endoplasmic reticulum (ER) called the "rough ER". read more

Those floating ribosomes make proteins that will be used inside of the cell. Other ribosomes are found on the endoplasmic reticulum. Endoplasmic reticulum with attached ribosomes is called rough ER. It looks bumpy under a microscope. The attached ribosomes make proteins that will be used inside the cell and proteins made for export out of the cell. read more