RIBOSOMES:
Ribosomes was first observed as dense granule using electron microscope. Ribosomes are non membranous body found in both prokaryotic and eukaryotic cells. However, eukaryotic ribosomes are larger and characterized as 80S ribosomes and prokaryotic ribosomes are characterized as 70S ribosomes. Ribosomes formed in nucleus and then tansported to cytoplasm by nuclear pores. Ribosomes are made by equal amount of RNA and protein so they are called RIBONUCLEOPROTEINS. They can be seen under electron microscope. Function of ribosome is protein synthesis(translation)In an eukaryotic cell ribosomes are freely dispersing in cytoplasm also found in Plastid and Mitochondria but these ribosomes are prokaryotic in nature mean 70S
The eukaryotic ribosomes are composed of two subunits of different sizes. The larger one is 60S and smaller one is 40S particles The two subunit on attachment form 80S ribosome. The attachment is controlled by salt bonds between phosphate group of RNA and amino group of amino acid. It was seen that some time many ribosomes attach on single mRNA such chain of ribosomes called POLYSOME OR POLYRIBOSOME
Comments
Post a Comment