70S ribosome

Definition

The 70S ribosome is a type of ribosome found in prokaryotic cells, responsible for protein synthesis. It is composed of two subunits: the 50S large subunit and the 30S small subunit.

5 Must Know Facts For Your Next Test

1. The 'S' in 70S stands for Svedberg unit, a measure of sedimentation rate during centrifugation.
2. The 70S ribosome is smaller than the 80S ribosomes found in eukaryotic cells.
3. It plays a crucial role in translating mRNA into proteins.
4. The 50S subunit contains two rRNA molecules (23S and 5S) and about 34 proteins.
5. The 30S subunit contains one rRNA molecule (16S) and about 21 proteins.

Review Questions

• What are the two subunits that make up the 70S ribosome?
• How does the size of the prokaryotic 70S ribosome compare to eukaryotic ribosomes?
• What function does the 70S ribosome perform in prokaryotic cells?

Related terms

Prokaryote: A unicellular organism that lacks a nucleus and membrane-bound organelles.

mRNA:

Messenger RNA that carries genetic information from DNA to the ribosome for protein synthesis.

rRNA:

Ribosomal RNA that forms part of the structure of ribosomes and catalyzes protein synthesis.