Ribosomes are tiny particles or a component in the cytoplasm of the cell or present on the surface of other organelles, that has RNA and other connected or related proteins. So in which organism ribosomes are present? Let’s have a deeper view.
Is Ribosomes Eukaryotic, No. Ribosome is an organelle. Ribosomes are present in both eukaryotic organisms and prokaryotic organisms. Ribosome is the place where the synthesis of protein is being done. They can be in the cytoplasm or inside any other organelle.
We all know the importance of protein.
They are basically the building blocks of a cell even if it’s for a smaller organism like bacteria etc or bigger animals like elephants etc. In order to gain new cells and repair the older or damaged cell, the body needs to synthesize protein.
Now this synthesis of protein happens inside an organelle called ribosome.
So, ribosomes are present in both eukaryotic organisms and prokaryotic organisms.
Prokaryotic organisms have 70s (S- Svedberg unit; The unit of Density ) ribosomes.
Eukaryotic organisms have 80s (S- Svedberg unit; The unit of Density) ribosomes.
Image Credits- Wikimedia
Is Ribosomes Eukaryotic organelle specifically?
Ribosome is an organelle that is not specifically membrane bound.
So, ribosomes are present in both prokaryotes like bacteria, archaea and in eukaryotes like animals, fungi etc.
Which type of ribosomes are found in bacteria?
The bacteria have simple structure with 3 type of ribosomal RNA: [30S+ 50S]
16S rRNA:
16S rRNA or 16S ribosomal RNA, (where S= Sediment Coefficient- During centrifugation process, the amount of sediment it forms) is a portion in the prokaryotic subunit (30S). It has 21 proteins.
23 S rRNA and 5S rRNA:
23 S rRNA and 5S rRNA, where rRNA- ribosomal RNA (where S= Sediment Coefficient- During centrifugation process, the amount of sediment it forms) is a portion in the 50S prokaryotic subunit. It has 31 proteins.
Now, during protein synthesis these 30S and 50S subunits get connected or combined and become 70S subunits which are about 25 nanometer in diameter.
FACT: Bacteria has about 15000 ribosomes in it.
Which type of ribosomes are found in mitochondria?
Mitochondria being an organelle has ribosomes in it.
Mitochondria has 70S types of ribosomes inside their matrix. These ribosomes are called mitoribosomes or mitochondrial ribosomes.
These ribosomes aid in the production or synthesis of protein that is required by mitochondria for energy production (ATP) or any other organelles.
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Where are ribosomes found in a eukaryotic cell?
In eukaryotic cells, ribosomes are found in many places based on their function and productivity.
Ribosomes in eukaryotic cell are present freely in the cytosol or cytoplasm or ribosomes are present on the surface of other membrane bound organelles like endoplasmic reticulum, mitochondria, plastids like chloroplasts.
Eukaryotic cells have complex mechanisms which require separate ribosomes for each one. This is the reason ribosomes are scattered like these for the synthesis of protein.
What type of ribosomes are found in prokaryotic cells?
Prokaryotic organisms like bacteria, archaea and cyanobacteria have the same type of ribosomes which is clearly discussed below.
Prokaryotic cell have 3 types of ribosomal RNA: [30S+ 50S]
16S rRNA:
16S rRNA or 16S ribosomal RNA, (where S= Sediment Coefficient- During centrifugation process, the amount of sediment it forms) is a portion in the prokaryotic subunit (30S). It has 21 proteins.
23 S rRNA and 5S rRNA:
23 S rRNA and 5S rRNA, where rRNA- ribosomal RNA (where S= Sediment Coefficient- During centrifugation process, the amount of sediment it forms) is a portion in the 50S prokaryotic subunit. It has 31 proteins.
Now, during protein synthesis these 30S and 50S subunits get connected or combined and become 70S subunits which are about 25 nanometer in diameter.
Which type of ribosomes are found in eukaryotic cells?
Eukaryotic cells perform complex cellular mechanisms and require protein or amino acid molecules to a great extent.
Eukaryotic cell on its own has an 80S subunit present on the cytosol and sometimes these ribosomes are attached in the surface of the other organelle like endoplasmic reticulum, chloroplasts, mitochondria.
Are ribosomes in prokaryotes and eukaryotes the same?
Prokaryotic organisms and eukaryotic organisms are entirely different in terms of their mechanisms and other factors.
When it comes to the prokaryotic ribosomes and eukaryotic ribosomes they are not the same. They are different with very few similarities.
The purpose of the ribosome is same in prokaryotes and eukaryotes, that is they provide the site for synthesis of protein. They are composed of RNA and other ribosome associated proteins.
What are 30S 50S ribosomes?
Ribosomes have 2 subunits in them.
30S and 50S ribosomes are the prokaryotic ribosomes which in combination makes the complete 70S subunit of ribosome.
What are 60S and 40S ribosomes?
Ribosomes have 2 subunits in them.
60S and 40S ribosomes are the eukaryotic ribosomes which in combination makes the complete 80S subunit of ribosome.
Difference between prokaryotic and eukaryotic ribosomes?
Though ribosomes are organelle, they differ when they appear in prokaryotic organisms and eukaryotic organisms based on their requirements.
Prokaryotic and eukaryotic ribosomes differ in many ways like their subunit, they vary in size, location etc.
Prokaryotic ribosome:
- Prokaryotic ribosomes are smaller- 70S ribosomes.
- It consists of 30S subunit and 50S subunit.
- Among these, 30S is the smaller subunit and 50S is the larger subunit.
- The mass is around 2700kd.
- The smaller subunit is composed of 16S RNA.
- The larger subunit is composed of 2 RNA that is 5S RNA and 23S RNA.
- Generally in prokaryotic organisms, ribosomes are seen free floating in the cytoplasm.
Eukaryotic ribosome:
- Eukaryotic ribosomes are larger- 80S ribosomes.
- It consists of 40S subunit and 60S subunit.
- Among these, 40S is the smaller subunit and 60S is the larger subunit.
- The mass is around 4200kd.
- The smaller subunit is composed of 18S RNA.
- The larger subunit is composed of 3 RNA that is 5S RNA, 5.8S RNA, 28S RNA.
- In eukaryotic organisms, ribosomes are present on the cytosol or cytoplasm and also on the surface of other membrane bound organelles such as endoplasmic reticulum, nucleus, mitochondria, chloroplasts etc.
Image Credits- Wikimedia
What are 70S and 80S ribosomes?
Now we understand that ribosomes are nothing but a machine that aid in protein synthesis.
The 70S and 80S are the prokaryotic and eukaryotic ribosomes respectively. In which 70S is the combination of 30S + 50S subunit and 80S is the combination of 40S+60S subunit of the ribosome.
Why do 60S and 40S make 80S not 100s?
The eukaryotic ribosome contains 60S and 40S subunits and in combination makes 80S subunits of the ribosome.
S is the svedberg unit which is the unit of sedimentation coefficient. During the centrifugation process, the contents will be pushed downward and upwards based on their weight.
The exact total sum will not be retained due to the forces like centrifugal force and gravity. This is why 60S and 40S make 80S not 100s.
Why do 50S and 30S make 70S ribosomes?
The prokaryotic ribosome contains 50S and 30S subunits and in combination makes 70S subunits of the ribosome.
S is the svedberg unit which is the unit of sedimentation coefficient. During the centrifugation process, the contents will be pushed downward and upwards based on their weight.
The exact total sum will not be retained due to the forces like centrifugal force and gravity. This is why, 50S and 30S make 70S ribosome.
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Hello, I am Sugaprabha Prasath, a Postgraduate in the field of Microbiology. I am an active member of the Indian association of applied microbiology (IAAM). I have research experience in preclinical (Zebrafish), bacterial enzymology, and nanotechnology. I have published 2 research articles in an International journal and a few more are yet to be published, 2 sequences were submitted to NCBI-GENBANK. I am good at clearly explaining the concepts in biology at both basic and advanced levels. My area of specialization is biotechnology, microbiology, enzymology, molecular biology, and pharmacovigilance. Apart from academics, I love gardening and being with plants and animals.
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