The ribosome is one of the most important membrane-bound organelles in the cell and is found in every cell. It is made up of a little sphere-shaped structure. It comprises protein and ribose nucleic acid (RNA), and it serves as a site for protein production. It may be present in cells, mitochondrial matrices, and chloroplasts of living organisms and cytoplasm. It may also be present on the outer membranes of the ER (endoplasmic reticulum) and the nucleus of the cell. The name ribosome is derived from the Greek words ‘ribo’, which means ribonucleic acid, and ‘soma’, which means body. Let us have a productive discussion on types of ribosomes.
Types of Ribosomes and their functions
The ribosome of an organism has the same size, volume, structure, content, and other characteristics regardless of the kind of cell it is found in. Depending on their size and sedimentation coefficient (S), ribosomes can be divided into two categories labelled as the 70s and 80s, respectively. A Svedberg unit is denoted by the letter “S.” If you have an ultracentrifuge, you may measure the sedimentation coefficient, which indicates how quickly a cell organelle settles.
The two types of the ribosome are as mentioned below:
- 70S Ribosome
- 80S Ribosome
Let’s learn each of them in detail:
- 70S Ribosome
This type of ribosome is also known as Prokaryotic Ribosome. They are quite tiny in size and have a sedimentation coefficient in the range of 70S. This type of ribosome is composed of two subunits: a large 50S subunit and a tiny 30S subunit. They can be found in prokaryotic cells (for example, bacteria and blue-green algae) and in the chloroplasts and mitochondria of eukaryotic cells. The molecular mass of the 70S ribosome is 2.5 x 106 daltons.
Function
When found in the prokaryotic cell, the major component, known as the 50S, is spherical with a noticeable “stalk” and a “central protuberance.” peptidyltransferase, which is located in the heart of the structure, is responsible for catalysing the creation of a polypeptide chain between the entering amino acid and the expanding chain of peptides. It is a thick and homogeneous particle with a 50S designation. The 30S component of ribosomes in prokaryotes is a short, thin, and elastic small subunit of ribosomes. The 30S chromosome contains the decoding core for mRNA and is separated into three domains: the head, body, and platform chromosomes.
- 80S Ribosome
This type of ribosome is also known as Eukaryotic Ribosome. These ribosomes are quite big and have a sedimentation coefficient of 80S, and they are composed of a large circular 60S subunit and a small elliptical 40S subunit. They can be present in all eukaryotic cells, including yeast.
Function
It is possible for Eukaryotic ribosomes to be connected with the endoplasmic reticulum or to exist freely in the cytoplasmic matrix. When they are linked to the endoplasmic reticulum to produce rough ER, they are connected to the endoplasmic reticulum by their component 60S. Ribosomes generate proteins in both the free and ER-bound states.
A large number of proteins produced on the ribosomes of the RER are either secreted or integrated into the ER plasma membrane as integral membrane proteins, respectively. Free ribosomes are the source of production for proteins that are neither secreted nor found in membranes. The nucleus, chloroplasts, and mitochondria are just a few of the organelles where some of the proteins produced by free ribosomes are placed. These molecules also aid the transfer of proteins into eukaryotic organelles such as mitochondria.
Other types of Ribosomes
Depending on where the ribosomes are located, they may be classified into one of the following types:
- Bacterial Ribosome
An example of this kind of ribosome is found in bacteria and has a sedimentation coefficient of the 70S, which indicates that it is present in bacteria.
- mitochondrial ribosome
- Mitochondrial Ribosomes are the scientific name for the ribosomes present in mitochondria. Many varieties exist, such as 73S mitochondrial ribosomes in fungi, 78S in plants, and 60S mitochondrial ribosomes in animals.
- Cytoplasmic Ribosomes
Cellular or cytoplasmic ribosomes are referred to as cytoplasmic ribosomes found in the cytoplasm.
- Plastic ribosomes
It is a term used to describe the kind of ribosomes present in chloroplasts, also known as plastid ribosomes. In higher plants, the 70S is found in the plastid ribosomes.
- Nuclear Ribosomes
Nuclear ribosomes are ribonucleoprotein particles that are located in the nucleus and are responsible for ribonucleoprotein synthesis.
- Nucleolar Ribosomes
Nucleolar ribosomes are RNP (ribonucleoprotein) particles of 150-200 nm in diameter that are located in the nucleus.
Conclusion
The primary function of a ribosome is the synthesis of new proteins. Ribosomes are found in all live cells and are responsible for the production of biological proteins. In addition to transporting newly created proteins, ribosomes serve as carriers of previously synthesised proteins. In biological processes, ribosomes serve as catalysts for the peptides’ transfer and s and hydrolysis. There are two types of ribosomes- 70S and 80S Ribosomes. The ribosomes in a cell are analogous to the kitchen in a home in terms of function. Food is cooked and prepared in the kitchen. It works in a similar way as ribosomes, which use amino acids to produce proteins.