Difference Between 70s And 80s Ribosomes

Difference Between 70s And 80s Ribosomes, Ribosomes are cell organelles mainly involved in protein synthesis within the cell. Ribosomes are made of RNA (Ribonucleic acid) and proteins, hence the name. Proteins are polymeric compounds of amino acids linked together through covalent polypeptide bonds. This process of linking amino acids in a chain is called Translation and is performed by ribosomes. Ribosomes are essential cell organelles in both animal and plant cells. They may float freely in the cell's cytoplasm or remain attached to the endoplasmic reticulum (ER). If the ribosomes are attached to the endoplasmic reticulum, it is called the rough endoplasmic reticulum (RER). If the ribosomes are not attached to the ER, it is called the smooth endoplasmic reticulum(SER). Two types of ribosomes are found in living cells- prokaryotic cells contain 70s ribosomes whereas eukaryotic cells have 80s ribosomes. The difference in both these types lies in the subunit structure. The 70s ribosomes have a larger 50s and a smaller 30s subunit. The 80s ribosomes have a larger 60s and a smaller 40s subunit.

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Structure

Many ribosomes are scattered within the cell's cytoplasm. Each ribosome is composed of two subunits. The two subunits of the ribosome seal around the mRNA and continue to move along the entire length assessing the three-letter codons. The transfer RNA docks at the ribosome because its nucleotide sequence matches the messenger RNA's.

A particular amino acid can be added to the end of the expanding protein chain by pairing each three-letter messenger RNA codon with the corresponding anticodon on a particular transfer RNA. The ribosome gets fragmented once the protein is completely translated.

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Function

Small, RNA- and protein-based structures involved in synthesising proteins are known as ribosomes. Several biological operations, such as restoring damaged cells and tissues or controlling biochemical processes, depend on proteins. Their key role is to translate genetic information into an amino acid sequence to be utilised to construct polymers of amino acids (proteins) from monomeric units. The ribosomes convert messenger RNA (mRNA) into proteins through the process of Translation.

The two subunits of the ribosomes are different in size and function. Subunits are composed of ribosomal RNA (rRNA) and various ribosomal proteins.

• The minor subunit (30s in prokaryotes and 40s in eukaryotes) is responsible for decoding. It is crucial for the initiation complex to develop because it interacts with the mRNA, initiator tRNA, and initiation factors. Moreover, it distinguishes between different aminoacyl tRNA molecules to provide translational fidelity. As a result, it is an easy target for ligands like toxins and antibiotics that prevent the synthesis of proteins.
• The major subunit (the 50s in prokaryotes and 60s in eukaryotes) is functional in catalysing the formation of peptide bonds. This is called peptidyl-transferase activity since the enzyme peptidyl transferase links amino acids with the help of transfer RNA (tRNA) molecules.

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Difference Between the 70s And 80s Ribosomes