Ribosomes
While studying the plant and animal cell, you might have come across many organelles that function together for carrying out the cell activities. One such important cell organelle is the ribosome, which is responsible for synthesis of proteins. While mitochondria are considered as powerhouse of the cell for energy production, ribosomes are popularly related as the site for protein synthesis in a cell. Before delving more about ribosomes function, let’s discuss in brief regarding the structure of ribosomes. You can read more on plant cell organelles and labeled animal cell diagram.
Ribosomes Composition and Structure
Ribosomes are composed of ribonucleic acid (abbreviated as RNA) and proteins, in nearly equal amounts. The ribonucleic acid is derived from the nucleolus, where ribosomes are synthesized in a cell. A simple prokaryotic cell (for example, bacteria) consists of a few thousands of ribosomes, whereas a highly developed eukaryotic cell (for example, human cell) has a few millions of ribosomes. Prokaryotic ribosomes are smaller in size as compared to the eukaryotic ones. Read more on similarities between prokaryotic and eukaryotic cells.
Coming to ribosomal structure, a typical ribosome consists of two subunits, each of which contains RNA and proteins. These two subunits are categorized with respect to the rate of sedimentation in a specific medium. For example, the two subunits in a eukaryotic cell are 40S (smaller subunit) and 60S (larger subunit), where ‘S’ stands for the density unit, Svedberg. Thus, the higher the value assigned to the subunit, the larger is the size of the subunit. » Read more: Ribosomes Function
