The Synthesis of Proteins

The lowest units of a living cell are made up of genetic information carried in small units of substances that make proteins. These substances that carry information about the genetic composition of a cell are known as genes. When the genes exhibit some variations, then they alter the way different cell is formed and ultimately how an entire organism manifests different physical traits that define it. The proteins are synthesized to form the cells in question through a series of steps at the molecular level. The purpose of this paper is to evaluate and explain the synthesis of proteins and explain the fidelity involved in synthesizing the proteins.

Protein Synthesis

            To understand the process involved in protein synthesis, it is worth exploring the molecular level where these activities occur. The entire process occurs outside the DNA on the cellular structure called the ribosome; this phase is called transcription (Cochella & Green, 2018). All the information of the DNA composition is carried from the nucleus to this site using components of the proteins. The resultant proteins are the building blocks of the cell. They control virtually all reactions at the molecular level of the cell, and also provide the structure of the cell and serves signals to nearby cells. Proteins are made up of long chains of amino acids. When they link up in different sequences, they influence the structure and function of the protein.  The genes dictate this sequence – it contains s detailed pattern on how that should happen.

Transcription and Translation Synthesis

            There are so many amino acids within the cell of a living organism. Many things can go wrong during cell replication in the growth process, but there are checks in place to stop that from happening (Drummond & Wilke, 2009). Shortly after the messenger ribonucleic acid (mRNA) copy is released from the nucleus and delivered to the ribosome, a curated synthesis of protein in the initiation phase is activated, and two ribosomal units fuse onto the mRNA material (Mohler & Ibba, 2017). The elongation phase then follows, whereby more amino acids are added to the chain growing as the ribosome read the mRNA nucleotide in groups of three units called codon. It then matches each codon with the transfer RNA (tRNA) called anticodon. Then the ribosome is unbound from the mRNA, and the resulting chain of the amino acid is processed into a final functioning protein marking the end of the protein synthesis.

Diagram:  Image showing  transcription and translation process

            The relatively smaller units of the formed codon and anti-codon activate a chain of events at the cellular level that consequently brings about the fusing of the larger ribosomal units and the smaller ribosomal units. Essentially, the correct protein is formed by mRNA and tRNA that are positioned to produce the desired protein. The protein synthesis fidelity begins to take shape here.

Diagram: protein synthesis process

Filtration Synthesis

            To guarantee fidelity, Mohler & Ibba, (2017) contend that the synthesis process needs to recognize the three-base codons on the mRNA, which carries the genetic code relating each amino acid to a codon made comprised of three letters as described by Watson-Crick base pairing. The process is analogous to replication of documents using a copier because it takes the content of the original word by word hence ensuring the synthesis is accurate. However, an error frequency should not exceed 0.0001 while forming the larger proteins.

            Further,  apart from transcription and translation, the fidelity is guaranteed in a series of sieve that ensures only the desired protein is synthesized. It is worth noting that the fidelity of the proteins synthesis depends on the discrimination between the complementary Watson-Crick base proteins and the non-complementary ones.  At this stage, there could be amino acids with similar properties but different sizes not matching the cognate amino acid. If activated, they can cause a frequency that is too high to maintain and give rise to a very ambiguous genetic code. There is a double sieve strategy in place to remove those that are either too big or too small. Also, the different sizes of these proteins make the sieving strategy an ideal measure; this occurs in a separate site that is distinct from the synthesis site. It is called the editing site. The stage involves enzyme activities as opposed to the physical sieving, the size as a factor dictates the analogy because it inhibits the occupation of the active sites on the cognate amino acids.

            In the first sieving, all the proteins larger proteins that cannot establish interaction with the cognate amino acid are acted upon by the synthetic enzyme. The small amino acid that can establish the interaction, however, go through the sieve, get activated and relocated to the tRNA. In the second sieve, much finer proteins are removed through a catalyzed hydrolysis of other amino acids and the alteration of the frequency to 1 per 1000 from the normal average 1 per 10000.

            In conclusion, protein synthesis is rather a discriminative and selective process. It occurs mainly on the ribosome. The process involves two major steps: the transcription which involves the capturing of the DNA copy using the mRNA, and the translation which involves the tRNA and mRNA coupling selectively according to the pattern that the mRNA contains. To fully optimize the fidelity of protein synthesis, the proteins can undergo a two-stage series of enzymatic hydrolysis and frequency modification at the editing site. The process has two stages, where the proteins that cannot fit the cognate amino acids are removed. The larger ones are removed in the first stage while the small ones are removed in the second.

Works cited

Cochella, L. & Green, R. (2018).  Fidelity in protein synthesis. Current Biology Vol 15 No 14 R536,

D. Allan Drummond, A, D., and Wilke, O, C. (2009). The evolutionary consequences of erroneous protein synthesis.  Macmillan Publishers

Mohler, K., & Ibba, M. (2017). Translational fidelity and mistranslation in the cellular response to stress. Nature Microbiology, 2(9), 17117.