Ribosomes are made of protein and ribosomal RNA. A ribosome is composed of two sub units, a smaller on and a larger one (sizes will vary depending on cell type), these sub units only come together in the presence of mRNA. Ribosomes are around 10-30nm and are found in both prokaryotic and eukaryotic cells as free floating ribosomes. In only eukaryotic cells we can also find ribosomes attached to the nuclear evelope as well as the Endoplasmic Reticulum, usually there are thousands of ribosomes in a cell.
Cells need to make proteins. Those proteins might be used as enzymes or as support for other cell functions. When you need to make proteins, you look for ribosomes. Ribosomes
are the protein builders or the protein synthesizers of the cell.
1.DNA is transcribed into mRNA.
2. mRNA goes out of the
nucleus through the nuclear pores and then the 2 subunits attach.
3. mRNA in the ribosome attracts the tRNA (which itself attracts amino acids).
4. Using the code in the mRNA the tRNA will bring in the amino acids to form a polypeptide chain in a specific order depending on what protein is being made.
After Protein Synthesis depending on which ribosome made the protein e.g if it was made by a bound ribosome meaning attached to the ER it will be used for extracellular purposes but proteins produced by free floating ribosomes are used within the cell. (Jayawardana, R. (2012). Ribosomes Movie. Available: DVD Script. Last accessed 12 March 2012)
Shops and Restaurants
Just as ribosomes can be found in numerous amounts around the cell we can find shops and restaurants either attached to buildings or as kiosks around an airport. These Restaurants and shops, following the guidelines provided to them by administration, produce many items for use inside the airport or out side the airport. In this case we can see that the ribosomes are the shops and the proteins are the products that they sell.