Please answer the question carefully In your own words descr

Please answer the question carefully.

In your own words, describe the process of protein synthesis, starting with the DNA, stored in the nucleus, and ending with the completed protein. Be sure to mention the terms code, codon, anticodon, mRNA, tRNA, amino acids and ribosomes in your answer.

Solution

Protein synthesis is an m-RNA guided process in which the individual cells build their specific proteins often referred to as translation.

The process involves unwinding of specific DNA part by certain specific enzymes stored in the nucleus. Now RNA copy of the unwinded DNA is made called transcription. Now this RNA moves from the nucleus into cell cytoplasm, wherein the ribosome, the protein synthesis takes place. In bacteria, we have 70S ribosome(50S and 30S subunit) whereas in eukaryotes larger subunit 80S subunit exist.

DNA sequence made up of nucleotide residue is specified by 4 code letters A, T, G, C. 3 nucleotide residues called codon code for each 20 amino acid. For example AUG - Initiation codon codes for methionine, UAA, UAG, UGA -termination codon do not code for any amino acid but signal the termination of protein biosynthesis.

In the t-RNA, there is 3 base sequence called anticodon which is able to bais-pair with m-RNA codon leading to codon-anticodon pairings.

The 3rd position in a codon is less specific than 1st and 2nd AND IS SAID TO WOBBLE.

Protein synthesis involves 5 stages:

1. Activation of amino acid

Amino acid covalently attaches to t-RNA called \"charged\" t- RNA using ATP energy, Mg2+, and enzymes such as aminoacyl t-RNA synthetase.

2. Initiation

A complex formed between ribosome unit, m-RNA, GTP, fMet-tRNA, 3 initiation factors

3. Elongation

Peptide bond formation and translocation.

4. Termination and Release

5. Folding and post-translation processing

Folding makes the polypeptide chain into active 3-dimensional form. Many proteins further undergo post-translation modifications such as amino-terminal and carboxyl-terminal modifications, modification of amino acids( addition of prosthetic group,/isoprenyl group etc)