What is the structure of a ribosome?

A ribosome is a complex molecular machine composed of proteins and ribonucleic acids (RNA) that synthesises proteins in cells.

The ribosome is a key component of the cell, responsible for the synthesis of proteins, which are essential for the structure, function, and regulation of the body's tissues and organs. It is composed of two main subunits: the large subunit and the small subunit. These subunits come together to form a functional ribosome only during protein synthesis, and they separate once the process is complete.

The large subunit is the site where the amino acids are joined together to form a polypeptide chain, which eventually folds into a protein. It contains a peptidyl transferase centre, which is responsible for forming peptide bonds between amino acids. The small subunit, on the other hand, is responsible for reading the messenger RNA (mRNA) that carries the genetic information for the protein to be synthesised.

Both subunits are composed of proteins and ribosomal RNA (rRNA). The rRNA provides the framework on which the proteins are arranged, and it also plays a crucial role in the catalytic activity of the ribosome. The proteins, meanwhile, stabilise the rRNA and help in the binding of other molecules during protein synthesis.

In terms of structure, ribosomes are not uniform across all organisms. In prokaryotes (organisms without a nucleus, such as bacteria), the ribosomes are smaller and have a different ratio of rRNA to protein compared to eukaryotes (organisms with a nucleus, such as humans). This difference is exploited in the development of antibiotics, which can target the bacterial ribosomes without affecting the human ones.

In summary, the ribosome is a complex structure composed of proteins and rRNA, with two main subunits that come together during protein synthesis. Its primary function is to synthesise proteins, a process that is vital for the survival and functioning of all living organisms.