Ribosomes

Topic Description

The ribosomes are large, complex, non – membrane bound organelles found within all living cells. Their primary function is to synthesize new proteins based on the DNA’s instructions which have been delivered to them via a mRNA strand. Ribosomes use these instructions to determine what amino acids, how many amino acids, and what order of amino acids are needed in order to build a protein. All the eukaryotes have 80 S ribosomes. This Eukaryotic ribosome consists of 40 S small subunit and 60 S large subunit. The large sub unit consists about 45 proteins and 3 rRNA molecules. Both of these sub units are produced by the nucleolus and released into the cytoplasm where the ribosome will be formed. When an mRNA molecule containing protein building instructions is Released by the nucleus, the two ribosomal subunits, one large and one small, will unite at a specific site on the mRNA to form the functional ribosome. Ribosomes in a cell are in two regions of the cytoplasm. They are found scattered in the cytoplasm and some are attached to the endoplasmic reticulum. When the ribosomes are bound to the ER they become a collective part of the organelle known as the rough endoplasmic reticulum. Both rough ER bound, as well as the free-floating ribosomes are similar in structure and go through protein synthesis the same. Ribosomes themselves are composed of both ribosomal RNA and proteins.  The rRNA is organized along with proteins to create the subunits. The catalytic activity of the ribosome is carried out by the RNA, The proteins that make up the ribosome reside on the surface and stabilize the structure