What is a ribosome and what does it do?
A ribosome is a complex molecular machine that plays a critical role in protein
synthesis. It is composed of two subunits, each containing a combination of
ribosomal RNA (rRNA) and proteins. The small subunit reads the messenger RNA
(mRNA) while the large subunit catalyzes the formation of peptide bonds between
amino acids.
Once the mRNA is bound to the small subunit, it is scanned for the presence of a
start codon, which signals the beginning of the protein-coding sequence. As the
mRNA is threaded through the ribosome, each three-letter codon is read and
matched to the corresponding amino acid by transfer RNA (tRNA) molecules. As
each amino acid is added to the growing polypeptide chain, the ribosome moves
along the mRNA until it reaches a stop codon that signals the end of the proteincoding sequence. The newly synthesized protein is then released into the cell.
The ribosome is considered one of the most complex molecular machines in the cell,
and it is crucial for all forms of life. It is responsible for the accurate and efficient
synthesis of proteins, which are essential for regulation, communication, and
metabolism. Ribosomes are most commonly found in the cytoplasm of the cell, but
they can also be found in the endoplasmic reticulum of eukaryotic cells, where they
synthesize proteins that are destined for secretion or insertion into the cell
membrane.
References:
- Wilson DN, Doudna Cate JH. The structure and function of the eukaryotic ribosome. Cold
Spring Harb Perspect Biol. 2012;4(5):a011536.
- Klinge S, Woolford JL Jr. Ribosome structure and assembly. Curr Opin Chem Biol.
2019;52:146-153.
- Ramachandran N, Hunte SL, Culver GM. Eukaryotic ribosome assembly, transport and
quality control. Genes Dev. 2020;34(11-12):768-799.