What is the role of ribosomes in prokaryotic cells?
Ribosomes are small complexes of RNA and protein that play a crucial role in
protein synthesis in prokaryotic cells. These structures are found in all living
cells, but they vary in structure and function. In bacterial cells, ribosomes are
smaller and less complex than those found in eukaryotic cells, allowing for
differences in antibiotic sensitivity and resistance.
In prokaryotic cells, ribosomes are responsible for translating information
encoded in messenger RNA (mRNA) into polypeptide chains. This process is
called translation, and it involves three stages: initiation, elongation, and
termination. During initiation, the ribosome is assembled on the mRNA, and a
tRNA molecule carrying the first amino acid of the chain is recruited to the
ribosome. During elongation, additional tRNA molecules are recruited to the
ribosome, each carrying an amino acid that will be added to the growing
polypeptide chain. As each new amino acid is added to the chain, the tRNA is
released from the ribosome and a new tRNA enters. Finally, during
termination, the ribosome reaches a stop codon on the mRNA, and the
polypeptide chain is released.
Ribosomes in prokaryotic cells are composed of two subunits, the large
subunit and the small subunit, which come together during translation. The
small subunit binds to the mRNA, while the large subunit catalyzes the
formation of peptide bonds between successive amino acids. The ribosome
contains three sites where tRNA molecules can bind: the A site, the P site,
and the E site. The A site is where new amino acids are added to the growing
chain, the P site is where the polypeptide chain is held during elongation, and
the E site is where tRNA molecules that have given up their amino acids are
released from the ribosome.
In summary, ribosomes play a crucial role in prokaryotic cells by catalyzing the
synthesis of proteins from mRNA. By understanding the structure and function
of these structures, researchers can delve deeper into the molecular biology
of bacterial cells and develop new antibiotics that target ribosomes and disrupt
their ability to synthesize proteins.
References:
1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular
Biology of the Cell. Garland Science.
2. Watson, J. D., Baker, T. A., Bell, S. P., Gann, A., Levine, M., & Losick, R. (2014).
Molecular Biology of the Gene. Pearson.