Both prokaryotic and eukaryotic cells both need an organelle to create proteins. Proteins are simply vast chains of amino acids that have been arranged in a sequence to form a specific protein. It can be said that there are several thousands of types of proteins that each have a specific purpose in a particular cell, and these proteins do not simply form out of chance. Rather, there is a specific organelle that transforms these chains of amino acids into a specific sequence in order to produce proteins. Even though information on ribosomes is still limited, scientists understand many operations that ribosomes contribute in cellular processes.
Functions of Ribosomes
Ribosomes are the tiny factories that are responsible for synthesizing the chains of amino acids into a particular protein. Since there are
literally thousands of ribosomes in cells, the amount of protein that needs to be created is directly related to how many ribosomes are in a particular cell. Therefore, if only a small amount of protein was needed only a small amount of ribosomes would also be needed.
In order to make a protein in a eukaryotic cell, the eukaryote’s nucleus first creates mRNA and sends it to the ribosome. When the ribosome receives this information, it takes its two subunits (60-S and 40-S) and clamps onto the mRNA. This process starts the formation of the protein. After this step, ribosomes search the cell for a nucleic acid called tRNA which is responsible for giving the ribosome instructions on how to make a specific protein. With this information, the ribosome is able to make long chains of amino acids into proteins.
In prokaryotic cells, the process is similar; however, the ribosomal subunits are called 50-S and 30-S.
Location of Ribosomes
The location of ribosomes depends on where a specific protein needs to be made. A ribosome can be included outside of a cellular membrane in order to make a specific protein (such as producing a membrane protein). Likewise, ribosomes can be accompanied in the interior of the cell in order to create other proteins that can be needed in other parts such as the cytoplasm. It can be concluded that ribosomes are located throughout the cell and are probably the most numerous organelle in a cell.
One very important site of ribosomes is the endoplasmic reticulum. When ribosomes are attached to the endoplasmic reticulum, it becomes the "rough" endoplasmic reticulum while a "smooth" one means that there are no ribosomes attached. The reason ribosomes attach to this system is because the endoplasmic reticulum can be thought of as a highway system which can transport proteins to other parts of the cell. The endoplasmic reticulum does this by exporting proteins using its numerous sacs called cisternae.
In regarding information on ribosomes, it is important to remember that the ribosomes can attach to the endoplasmic reticulum at any time and do not have to be attached in order to synthesize proteins.
- Biology4Kids.com. 1999. Ander Radio Studios. 13 January 2010 <https://www.biology4kids.com/files/cell_ribos.html>.
- Curtis, Helena and N. Sue Barnes. Biology. 5th ed. New York: Worth Publishers, Inc., 1989.
- Adrignola. "Rought Endoplasmic Reticulum." https://commons.wikimedia.org/wiki/File:Rough_endoplasmic_reticulum.JPG
- LadyofHats. "TRNA Ribosomes Diagram." https://commons.wikimedia.org/wiki/File:TRNA_ribosomes_diagram_en.svg
- Vossman. "Ribosome Shape." https://commons.wikimedia.org/wiki/File:Ribosome_shape.png