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NEET Difference Between 70S and 80S Ribosomes

Last updated date: 16th May 2024
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An Introduction to 70S and 80S Ribosomes

Ribosomes are essential cellular structures involved in protein synthesis across all living organisms. They have significantly contributed to our understanding of biology, enabling advancements in medical research and biotechnology. A notable incident occurred in the early 2000s when scientists investigating antibiotic resistance discovered that certain bacteria had developed the ability to survive antibiotics that typically inhibit protein synthesis.

This led to the realisation of the pivotal role of ribosomes in antibiotic resistance, as specific mutations in ribosomal genes altered their structure, reducing susceptibility to antibiotics. This incident highlighted the significance of studying ribosomes and their variations, such as the 70S and 80S ribosomes, in unravelling the complexities of molecular biology and its implications in diverse scientific and medical fields. So in this article, we will look deeply into the difference between 70S and 80S ribosomes

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Definition of 70S and 80S Ribosomes

70S Ribosomes: Ribosomes found in prokaryotic cells (bacteria and archaea) consisting of a 50s large subunit and a 30s small subunit.

80S Ribosomes: Ribosomes found in eukaryotic cells (plants, animals, fungi) consisting of a 60s large subunit and a 40s small subunit.

Let's understand more about it by going through their facts and how they are important. In this way, I will be able to explain 70S and 80S ribosomes in more detail.

Interesting Facts about 70S and 80S Ribosomes:

Ribosomes are essential cellular organelles involved in protein synthesis. They can be classified into two main types: 70S and 80S ribosomes. The distinction between these ribosomes lies in their presence in different types of organisms. Bacterial and archaeal cells contain 70S ribosomes, while eukaryotic cells, including those in plants, animals, and fungi, possess 80S ribosomes.

70S Ribosomes:

70S ribosomes are smaller in size compared to 80S ribosomes. They exhibit higher resistance to certain antibiotics, making them an attractive target for antibiotics specifically designed to inhibit bacterial protein synthesis. This resistance is attributed to structural differences in the ribosomal subunits, which make it more challenging for antibiotics to bind and interfere with protein synthesis. The presence of 70S ribosomes in prokaryotes suggests their ancient evolutionary origin, representing an early form of protein synthesis machinery in cellular life.

80S Ribosomes:

In contrast to 70S ribosomes, 80S ribosomes are larger and more structurally complex. They consist of a 60s large subunit and a 40s small subunit. The 80S ribosome showcases diversity within its subunits, with various ribosomal RNA molecules and associated proteins contributing to its functional assembly. These ribosomes are primarily located in the cytoplasm of eukaryotic cells. However, they also have a notable presence associated with the endoplasmic reticulum (ER), where they participate in the synthesis of proteins that are destined for the ER or other membrane-bound compartments.

These facts guide us towards understanding the  70S and 80's Ribosomes difference.

Difference Between 70S and 80S Ribosomes: 



70S Ribosomes

80S Ribosomes



Smaller size

Larger size




Cytoplasm and ER


Protein Synthesis

Bacterial and archaeal



Antibiotic Target

Streptomycin and Tetracycline

Cycloheximide and 



Energy Requirement

Lower energy requirement for protein synthesis

Higher energy requirement for protein synthesis

Characteristics of 70S and 80S Ribosomes: 

Below are the distinguishing characteristics of 70S and 80S ribosomes, highlighting their structural features, locations, and roles in protein synthesis.

70S Ribosomes:

Size and Structure: 70S ribosomes are smaller in size compared to 80S ribosomes. They consist of a 50s large subunit and a 30s small subunit, which combine to form the functional ribosome. The small subunit contains 16s ribosomal RNA (rRNA), while the large subunit contains 23s and 5s rRNA.

Location: 70S ribosomes are primarily found in the cytoplasm of prokaryotic cells, including bacteria and archaea. They are responsible for synthesising proteins needed for the functioning and survival of these organisms.

Protein Synthesis: 70S ribosomes are involved in synthesising proteins in prokaryotic cells. They read the messenger RNA (mRNA) transcript and catalyse the formation of peptide bonds between amino acids, resulting in the production of proteins essential for cellular processes.

80S Ribosomes:

Size and Structure: 80S ribosomes are larger and more complex than 70S ribosomes. They consist of a 60s large subunit and a 40s small subunit, which join together to form the functional ribosome. The small subunit contains 18s rRNA, while the large subunit consists of 28s, 5.8s, and 5S rRNA.

Location: 80S ribosomes are found in the cytoplasm of eukaryotic cells. They are responsible for synthesising proteins that fulfil various functions within the cell, including enzymatic activity, structural support, and cellular signalling.

Endoplasmic Reticulum Association: In addition to their cytoplasmic location, a significant portion of 80S ribosomes is associated with the endoplasmic reticulum (ER). These ER-bound ribosomes participate in the synthesis of proteins destined for secretion or membrane insertion.


70S and 80S ribosomes exhibit distinct characteristics. 70S ribosomes are smaller in size, primarily found in the cytoplasm of prokaryotes, and are involved in protein synthesis in bacteria and archaea. In contrast, 80S ribosomes are larger and more complex, located in the cytoplasm of eukaryotic cells, and participate in the synthesis of a wide range of proteins. Additionally, a fraction of 80S ribosomes are associated with the endoplasmic reticulum, playing a role in membrane-bound protein synthesis. In this way, we were able to understand 70S and 80S ribosome differences and how useful they are.

FAQs on NEET Difference Between 70S and 80S Ribosomes

1. Are 70S and 80S ribosomes found in all living organisms?

No, 70S ribosomes are found in prokaryotes, which include bacteria and archaea. These organisms have a simpler cellular structure compared to eukaryotes. On the other hand, 80S ribosomes are found in eukaryotes, which include plants, animals, fungi, and protists. Eukaryotic cells are more complex, with membrane-bound organelles and a distinct nucleus.

2. Why are 70S ribosomes more resistant to antibiotics?

70S ribosomes exhibit a higher resistance to certain antibiotics compared to 80S ribosomes. This is due to differences in their structure and composition. Antibiotics like streptomycin and tetracycline target bacterial ribosomes by binding to specific sites on the 70S ribosome subunits. These antibiotics interfere with protein synthesis in bacteria, leading to their inhibition or death. However, eukaryotic cells with 80S ribosomes have structural variations in these binding sites, making them less susceptible to these antibiotics.

3. Can the 70S and 80S ribosomes function interchangeably?

No, 70S and 80S  ribosomes have evolved to perform protein synthesis in their respective organisms and cannot function interchangeably. The differences in their structure, composition, and associated factors make them specific to their corresponding cellular environments. Prokaryotes, with 70S ribosomes, have adapted their protein synthesis machinery to match the structure and function of these ribosomes. Similarly, eukaryotes, with 80S ribosomes, have evolved mechanisms and regulatory processes that are tailored to the characteristics of these ribosomes and the complexity of their cellular organisation.