80S ribosomes

Definition

80S ribosomes are large ribonucleoprotein complexes found in the cytoplasm of eukaryotic cells responsible for protein synthesis. They are composed of a 60S large subunit and a 40S small subunit.

5 Must Know Facts For Your Next Test

1. 80S ribosomes are distinct from prokaryotic 70S ribosomes, which have different structural and functional properties.
2. The 'S' in 80S stands for Svedberg unit, a measure of sedimentation rate during centrifugation.
3. The 60S large subunit contains three rRNA molecules (28S, 5.8S, and 5S) and about 49 proteins.
4. The 40S small subunit contains one rRNA molecule (18S) and about 33 proteins.
5. 80S ribosomes play a critical role in translating mRNA into polypeptides during the process of translation.

Review Questions

• What are the two main subunits that constitute an 80S ribosome?
• How do eukaryotic 80S ribosomes differ from prokaryotic ribosomes?
• What is the significance of the Svedberg unit in describing ribosome components?

Related terms

Ribosome:

A cell organelle that functions as the site of protein synthesis.

rRNA:

Ribosomal RNA; a type of RNA that makes up part of the structure of ribosomes.

Translation:

The process by which mRNA is decoded by a ribosome to produce a specific polypeptide.