Polysome

Definition

A polysome, also known as a polyribosome, is a complex formed by multiple ribosomes simultaneously translating a single mRNA strand. This structure allows for the efficient synthesis of many copies of a protein from one mRNA molecule.

5 Must Know Facts For Your Next Test

1. Polysomes increase the efficiency of protein synthesis by allowing multiple ribosomes to translate the same mRNA simultaneously.
2. They can be found in both prokaryotic and eukaryotic cells, facilitating rapid protein production in response to cellular needs.
3. Electron microscopy can be used to visualize polysomes, revealing their characteristic 'beads-on-a-string' appearance.
4. The formation of polysomes is crucial for cells that require high levels of certain proteins quickly, such as during cell growth or stress responses.
5. Ribosomal subunits in polysomes are held together through interactions with the mRNA and translation factors.

Review Questions

• What advantage do polysomes provide in terms of protein synthesis?
• How can polysomes be visualized within a cell?
• Why are polysomes particularly important for cells requiring rapid protein production?

Related terms

Ribosome: A molecular machine composed of rRNA and proteins that translates mRNA into a polypeptide chain.

mRNA: Messenger RNA, which carries genetic information from DNA to the ribosome for protein synthesis.

Translation: The process by which ribosomes synthesize proteins using the genetic information encoded in mRNA.