A protein comprises long chains of amino acids that are bonded together. Of the 20 amino acids, 10 have subunits that attract water, while the rest don't. The backbone of these acids is that they are able to form firm bonds, while the amino acids that don't attract water form fragile bonds. As a result of this, such acids have the ability to be flexible, and are also able to change shape at will. The most vital aspect of proteins is that arrangement of amino acids determines their function.
Steps of Protein Synthesis
There are three major phases:
In this phase, the pattern of nucleotides in the double coil DNA form are genetically converted into one strand of messenger RNA. At a time, 3 nucleotides become commands for one amino acid. In a single strand of DNA, 1,200 nucleotides are present. Thus, there should be 400 amino acids generated, which would represent just a single gene in a strand of DNA. Since there are an extraordinarily huge number of genes present in a human body, it can be tough to imagine the enormity of this process.
This is the phase, wherein an amino acid is connected to one end of RNA. At the other end, a particular code of 3 nucleotides will be joined at the mRNA stage. A huge variety of amino acid activating enzymes are present. The various steps involved in this phase are:
A single ATP molecule slides into the activating enzyme, in a place particularly designed for it.
An amino acid then settles at a place specifically reserved for it.
Both, the amino acid as well as the ATP molecules start moving closer to each other till they bind together. This results in two phosphates getting released, thereby energizing the amino acid.
Now, the adapter settles in its reserved position besides the amino acid.
The amino acid and adapter start moving towards each other and consequently bond.
The ATP molecule gets released, but only after all its energy is sifted into the bond.
Eventually, the activating enzyme discharges the adapter, which has the amino acid connected at the other end.
In this phase, a single amino acid gets attached to an adapter. It takes a lot of amino acids to make up a protein. Hence, there needs to be a mechanism by which these acids get connected to produce a single protein. The ribosomes make this possible. They interpret the nucleotide code, and link it to the correct amino acid. The steps involved in this phase are listed below.
The smaller part of the ribosomes attracts a messenger RNA.
The first 3 nucleotides of a messenger RNA are matched with the first adapter.
Now, the bigger part of the ribosomes is joined to the smaller part.
The second adapter slides into a position to the left of the initial adapter.
Posterior connectors of the two amino acids are present towards the end of the adapter links.
The initial adapter gets released as the RNA messenger moves to the right. This creates an empty area to the left of the second adapter. The released adapter has two amino acids linked at the ends.
This process continues as more and more adapters keep arriving. The new ones connect their amino acid chains, and the older ones are released. Thus, the number of amino acids linked to the adapter increases.
The process comes to a halt when the last 3 nucleotide code is unable to find an adapter that can hold it.
The ribosomes then discharge the mRNA, and proteins are formed out of the amino acid chain.
There are a huge number of ribosomes, which work together to generate proteins. Hence they are also known as the 'protein factory'.
The most interesting fact is that for every unique arrangement of amino acids, a different protein is formed.