Important Topic of Biology: Ribosomes

As science is well developing in these years where we are knowing about many things by doing numerous researches. In the same way, scientists were eager to know how our body was made, they conducted numerous experiments and made available for us how our body is made and what hid inside this flesh body. 

There will be one thing which we call base in every work or any material. So what do you think about the base or basic thing of our body? Where is this thing which we are calling ribosome located? What does it actually do? What happens when we don’t have it? Is it empty or made up of any structure?

The cell is the basic unit of the body from which all our organs, tissues are formed in a whole structured living organism. The cell is not naked visible. Even in these tiny particles, they are organelles that perform their functions. The ribosome is one of the organelles in cells. 

They are particularly round in shape and perform protein synthesis in cells. By its function, it is known as a site for protein synthesis.

Overview

Ribosomes are macromolecules within the cells that perform biological protein synthesis. They are present in all cells. They are in large numbers in cells. They are present in prokaryotes and eukaryotes mainly present on the surface of the endoplasmic reticulum in eukaryotes. If they are not attached to the endoplasmic reticulum they are also known as free ribosomes. Free ribosomes are the site for protein synthesis needed to maintain the cytoplasmic enzymatic reaction.

The term ribosomes were trimmed by haguenau in 1958. Ribosomes were first observed by George in 1950’s as dense particles or granules. Ribosomes attach to messenger RNA and use their sequence for determining the correct sequence of amino acids to generate a given protein. Amino acids carry ribosomes by transferring RNA molecules which will further go into binding with messenger RNA with the help of anticodon. For every coding triplet in messenger RNA, a unique transfer RNA must have the exact anticodon match and should have the correct amino acid for incorporating into a growing polypeptide chain.

A ribosome is made up of complexes of RNA and proteins which are called ribonucleoproteins. Each ribosome is composed of small and large components called subunits which are bound together.

1. The 30S subunit of the ribosome has mainly a decoding function that is bound to mRNA.
2. The 50S subunit of the ribosome has a mainly catalytic function which binds to aminoacylated tRNA.

In ribosomes the synthesis of protein from their building blocks take place in four stages:

1. Initiation
2. Elongation
3. Termination
4. Recycling

• Structure of ribosome: It is a complex structure made up of specialized RNA known as ribosomal RNA and present of proteins. The ribosomal proteins and rRNAs are arranged into two ribosomal pieces of different sizes which are also known as subunits. A large number subunit is known as a large subunit and another one is known as a small subunit of the ribosome. Ribosomes work together to translate mRNA into a polypeptide chain during protein synthesis. The subunits are of different sizes.
• Prokaryotic ribosome: Its size is 20nm, having 65% rRNA and 35% ribosomal protein. Prokaryotes has 70S ribosomes with 30S small unit and 50S large unit of the ribosome. The protein component of ribosomes does not directly participate in peptide bond formation catalysis but this protein acts like a scaffold that enhances the ability of rRNA to synthesize protein.
• Archeal ribosomes: Archeal ribosomes have the same ribosomes as bacterial ribosomes have 70Sriboses with the 30S and 50S subunits with three rRNA chains. They are much closer to eukaryotic ribosomes than bacterial ones.
• Eukaryotic ribosomes: They have 80S types of ribosomes with 40S small unit ribosomes and 60S large unit ribosomes in the cytosol.
• Plastoribosomes and mitoribosomes: In eukaryotes, ribosomes are present in mitochondria which are known as mitoribosomes, and in plastids such as chloroplasts which are known as plant ribosomes. The ribosome count is 70S particles. These are similar to bacteria the organelles have originated as symbiotic bacteria.

Functions of ribosomes

The main function of the ribosome is translating the messenger RNA encodes genetic information into proteins. And some other functions of ribosomes are:

1. Read codon at a time.
2. Incorporation of one amino acid into a progressively longer protein chain.
3. tRNA molecules bring amino acids to the ribosomes.
4. Ribosomes can recognize and bind to the correct pair of nucleic acids specified by anticodon with attached amino acids.
5. Ribosome stops codon on mRNA translation stops leading to separating and detaching the subunits from messenger RNA releasing completed proteins.
6. Needed for many cellular functions like repairing damage etc.
7. Convert genetic code into an amino acid sequence to build protein polymers from monomers.
8. Important in peptidyl transfer and peptidyl hydrolysis.

Importance of this chapter

The cell is the basic unit of the body from which all our organs, tissues are formed in a whole structured living organism. The cell is not naked visible. Even in these tiny particles, they are organelles that perform their functions. The ribosome is one of the organelles in cells. They are particularly round in shape and perform protein synthesis in cells. By its function, it is known as a site for protein synthesis. Ribosomes are macromolecules within the cells that perform biological protein synthesis. They are present in all cells. They are in large numbers in cells. They are present in prokaryotes and eukaryotes mainly present on the surface of the endoplasmic reticulum in eukaryotes.

This chapter is crucial as it explains the basic unit of the cell which is the cell and the organelles in it. This chapter takes the main role as it explains the main role of organelle in living cells. As it explains the ribosome functions and its parts. The structure of ribosomes and the role they played in metabolism or other activities. We should study this chapter as it tells the cell organelle where the cell is the basic unit of life. We need to learn it basically. Examiner won’t give a question paper by leaving this area questions. Ribosomes are the protein synthesis of the cell, it is the main part or organelle of the cell which we just can’t leave while preparing for our competitive exams. We just know the main function of the ribosome; many of us don’t know the other functions it plays in cells. So, there is a chance of asking questions about the other functions of the ribosome except for energy production. We can say that two to five bits can come from this area which is good to score high marks. If you failed to get the information about cell organelles or mainly about important cell organelles, anyone can guarantee you of scoring high. So, don’t neglect this area which brings you to score easily.

• Prokaryotic ribosome: Its size is 20nm, having 65% rRNA and 35% ribosomal protein. Prokaryotes has 70S ribosomes with 30S small unit and 50S large unit of the ribosome. The protein component of ribosomes does not directly participate in peptide bond formation catalysis but these proteins act like scaffolds; they enhance the ability of rRNA to synthesize protein.
• Archeal ribosomes: Archeal ribosomes have the same ribosomes as bacterial ribosomes have 70Sriboses with the 30S and 50S subunits with three rRNA chains. They are much closer to eukaryotic ribosomes than bacterial ones.
• Eukaryotic ribosomes: They have 80 S types of ribosomes with 40S small unit ribosomes and 60S large unit ribosomes in the cytosol.
• Plastoribosomes and mitoribosomes: In eukaryotes, ribosomes are present in mitochondria which is known as mitoribosomes, and in plastids such as chloroplasts which are known as plant ribosomes. The ribosome count is 70S particles. These are similar to bacteria the organelles have originated as symbiotic bacteria.