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What is Protein Synthesis & How Does it Work?

You’ve likely heard that protein is one of the four major building blocks of our cells, but do you know how it changes from the meat we eat to the macromolecular component in every cell in every living organism? 

Protein synthesis is the intricate process through which cells craft proteins, essential molecules that play diverse roles, from catalysing reactions to forming structures. This unfolds in two steps: transcription and translation. The former occurs in the nucleus, where a section of DNA is transcribed into a complementary messenger RNA (mRNA) molecule. The latter takes place in the ribosomes, where the information encoded in the mRNA is used to build a protein.

Let’s dive deeper into the fundamental process at the heart of life's machinery.

What is The Site of Protein Synthesis?

The ribosome is the macromolecular machine where protein synthesis occurs. Composed of ribosomal RNA (rRNA) and proteins, ribosomes read the genetic code carried by mRNA and oversee the assembly of amino acids into a polypeptide chain - the precursor to a functional protein.

What is The Purpose of Protein Synthesis?

The purpose of protein synthesis is far-reaching. Protein synthesis creates and maintains the proteins that are essential for the structure, function, and regulation of the body's cells and tissues. 

Proteins are the workhorses of the cell, participating in nearly every aspect of life's processes. Enzymes, a class of proteins, drive chemical reactions; structural proteins provide support and integrity to cells and tissues; hormones regulate bodily functions; and antibodies defend against infections. Essentially, protein synthesis ensures the perpetuation of life's functions and adaptations.

What Role Does Protein Synthesis Have in Exercise?

Protein is known to be a crucial supplement for regular gym-goers and fitness enthusiasts. Here are the ways in which the synthesis of protein plays a role in exercise:

  • Muscle Growth and Repair: During exercise, especially resistance training or strength training, stress is placed on muscle fibres. This stress triggers a process known as muscle protein synthesis, where new proteins are created to repair and strengthen the damaged muscle fibres. This is how muscles grow and become stronger over time!

  • Recovery: After a workout, the body needs to recover and repair the tissues that were stressed during exercise. Protein synthesis helps repair damaged tissues and build new cells, making protein essential for the recovery process.

  • Energy Metabolism: While carbs and fats are our primary sources of energy during exercise, proteins can also contribute to energy production, particularly during prolonged or intense activity. This occurs when amino acids from proteins are broken down and used for energy when your body doesn’t have other fuel sources to work with.

  • Immune Function: Many immune system components, including antibodies and immune cell receptors, are made up of proteins. Regular exercise can have positive effects on the immune system, and protein synthesis is crucial for maintaining a healthy immune response.

  • Enzyme Activity and Cellular Functions: Enzymes are proteins that catalyse various biochemical reactions in the body. These reactions are vital for energy production, nutrient metabolism, and overall cellular function. Regular exercise can influence the expression and activity of enzymes involved in these processes.

To support these exercise-related functions, active individuals often need more protein than those who don’t engage in regular exercise. This is because exercise increases the demand for amino acids, the building blocks of proteins. Getting in enough protein through food and supplements helps provide the necessary amino acids for muscle repair, growth, and overall recovery after exercise.

What is The First Step of Protein Synthesis?

The fascinating synthesising process begins with a process called transcription. Within the nucleus, the cell's DNA unwinds when the enzyme RNA polymerase binds to a region of a gene called the promoter sequence. This signals the DNA to unwind so the enzyme can “read” the bases of DNA, revealing the genetic instructions for building a protein. The RNA polymerase transcribes a specific gene's sequence into a complementary mRNA strand, creating a transcript that mirrors the original DNA sequence. 

What is The Second Step of Protein Synthesis?

As the mRNA transcript emerges from the nucleus, it travels to the ribosomes, the bustling factories of the cell. Here, the second act, translation, takes place. Transfer RNA (tRNA) molecules, each linked to a specific amino acid, glide along the mRNA, interpreting its code. The tRNA molecules contribute their amino acids to the growing polypeptide chain, following the instructions encoded in the mRNA.

DNA replication is so incredible because the correct amino acids are added to the polypeptide chains for correct gene expression. The RNA molecules are so highly specialised that the correct amino acid sequence is always used in the creation of a protein molecule.

Concluding Protein Synthesis

Protein synthesis underscores the elegance of molecular biology. From the intricate steps of transcription to the translation of mRNA codon to create protein molecules, this process sustains life. Each protein born from this complex process has a unique role to play. It’s not all about gains and great leg days, protein is crucial for the entirety of life.