Courses for Kids
Free study material
Offline Centres
Store Icon

Difference Between the 70S and 80S Ribosomes

share icon
share icon

About Ribosomes

Ribosomes are the particles present in the cells in large numbers and mainly serve as a site for protein synthesis. They are present as free particles in both prokaryotic and eukaryotic cells and also attached to the membrane of the endoplasmic reticulum in the case of eukaryotic cells. The discovery of ribosomes was in the year 1955 by a Romanian-American cell biologist George E. Palade; during his discovery, he found that ribosomes are associated with the endoplasmic reticulum in eukaryotic cells. 


Along with protein synthesis, they also function by binding to a messenger ribonucleic acid (mRNA) and decoding the information carried by the nucleotide sequence of the mRNA. The transfer RNA’s having amino acids enters into the ribosomes at the acceptor site. Once after getting added up, it further adds amino acids to the growing protein chain on tRNA.


Difference Between the 70S and 80S Ribosomes

70S Ribosome

80S Ribosomes

They are majorly found in prokaryotic cells like bacteria and they are also found in a few eukaryotic cells. 

Majorly found in eukaryotic cells. 

They are found in free states inside the cytoplasm in prokaryotic cells, whereas in the case of eukaryotic cells, they are found in a few organelles like mitochondria and chloroplast. 

Mainly found in the cytoplasm or attached to the endoplasmic reticulum. 

Their synthesis mainly occurs inside the cytoplasm of prokaryotes. 

Their synthesis mainly occurs inside the nucleolus. 

Their smaller subunit is 30S and larger is 50S

Their smaller subunit is 40S and larger is 50s. 

They have 3 molecules of RNA.

They have 4 molecules of RNA. 

Their weight is approx 2.7-3.0 million Daltons.

Their weight is approx 4.0-4.5 million Daltons. 

Their sedimentation coefficient is 70. 

Their sedimentation coefficient is approx 80. 

There are about 55 protein molecules, with 34 in larger subunits and 21 in smaller subunits in 70s ribosomes. 

There are about 73 protein molecules, with 40 in larger subunits and 33 in smaller subunits. 

They have approx 8,000 amino acids. 

They have approx 16,000 amino acids. 

RNA-to-Protein ratio is 2:1. 

RNA-to-Protein ratio is 1:1. 

Antibiotics inhibit protein synthesis. 

Antibiotics do not inhibit protein synthesis. 

Want to read offline? download full PDF here
Download full PDF
Is this page helpful?

FAQs on Difference Between the 70S and 80S Ribosomes

1. What is the importance of Ribosomes in a Human cell?

Ribosomes act as the storehouse of the genetic material of human beings. These can be RNA or DNA. The function of both these entities is very different, but both are dependent on their synthesis from the amino acids. Every human being has a distinct genetic code. This genetic code, even though it is unique for all living organisms, can be traced thousands of generations to our forefathers.

2. What are Eukaryotes?

A Eukaryote is a cell or an organism that possess a clearly defined nucleus. The eukaryotic cell consists of a nuclear membrane that surrounds the nucleus, in which there are well-defined chromosomes. The eukaryotic cell also consists of organelles that include mitochondria, Golgi apparatus, endoplasmic reticulum and lysosomes. The eukaryotes are thought to have evolved around 1.8 billion years ago.

3. What is the difference between DNA and RNA?

DNA and RNA are both macromolecules that are considered essential for all known forms of life. The chemical structure of DNA is very similar to that of RNA. The major difference between DNA and RNA is that RNA contains sugar ribose, while DNA contains slightly different sugar deoxyribose. Also, RNA has the nucleobase uracil while DNA contains thymine. Unlike DNA, most RNA molecules are single-stranded and can attain very complex three-dimensional structures.

4. I am having trouble while studying the subject on Ribosome; what shall I do?

The topic of Ribosome is a fairly complex one from the standpoint of entrance examinations in the medical field and also the school and board examinations. However, it is essential that you get a good hold of the subject as this is very important for higher studies, especially in the field of genetic research. Try asking doubts to your teachers and access the online resources available at Vedantu, where write-ups on a particular topic along with the solved questions are easily accessible to the students.

5. Explain the Functioning of Ribosomes?

Some of the important functions of ribosomes are discussed below:

  1. Their major function is assembling amino acids for the formation of protein which is essential to carry out cellular functions.

  2. Synthesis of mRNA from DNA by the process of DNA transcription. 

  3. Synthesis of mRNA in the nucleus and its transportation to the cytoplasm is done by ribosomes for the synthesis of protein. 

  4. Synthesis of protein with the help of tRNA, as the ribosomal subunits in the cytoplasm are bound around mRNA polymers. 

  5. Synthesis of protein occurs in the cytoplasm and is utilised in the cytoplasm itself, whereas the protein which is synthesised by bound ribosomes are exported outside.  

6. Explain the Composition of Ribosomes?

Ribosomes are composed of two subunits, they are:

A. The small ribosomal subunits- these subunits read the mRNA. 

B. The large ribosomal subunits- these subunits mainly help in the formation of polypeptide chains of amino acids.

Competitive Exams after 12th Science