Difference Between 70S and 80S Ribosomes

Ribosomes are very important cellular organelles that are tasked with synthesizing proteins. Proteins play many roles in our body – from repairing cellular damage to providing structural support. Life, as we know it, is classified into prokaryotes and eukaryotes, each with its own special ribosome structure. Eukaryotic ribosomes are called 80S ribosomes while prokaryotes such as bacteria have a smaller version called 70S ribosomes. Read on to explore more differences between the two.

Difference Between 80S and 70S Ribosomes

70S Ribosome

80S Ribosome


In prokaryotes such as bacteria. Also occurs in eukaryotic cells

Exclusively occurs in eukaryotes

In the Cell

Found freely inside the cytoplasm of prokaryotes. ALSO occurs in eukaryotic cell organelles such as mitochondria and chloroplast

Found inside the cytoplasm or attached to the Endoplasmic reticulum


Synthesized inside the cytoplasm of prokaryotes

Synthesized inside the nucleolus


Small 30S and large 50S

Small 40S and large 60S


3 molecules of RNA

4 molecules of RNA


2.7-3.0 million Daltons

4.0-4.5 million Daltons

Sedimentation Coefficient



Number of proteins

55 protein molecules, with 34 in larger subunit and 21 in smaller subunit

73 protein molecules, with 40 in larger subunits and 33 in smaller subunits

Number of Amino Acids

Around 8,000

Around 16,000

RNA-to-Protein ratio

2:1 (more RNA)


Influence of Antibiotics

Protein synthesis is inhibited by antibiotics

Protein synthesis is NOT inhibited by antibiotics

Further Reading:

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