Amino Acids: The Building Blocks of Protein

Researching about proteins to incorporate into your healthy lifestyle, you might have come across the phrase “amino acids the building blocks of protein” or something similar about amino acid components on a protein formula.

To know more about protein and why it is important for our overall health, you must know the fundamental player that composes it which is an amino acid.

Amino acids are the building blocks of protein and knowing more about them will lead to a better understanding of proteins.

Knowing about protein and amino acids will also make you a smarter buyer as you will identify which protein formula will be more effective to supplement your body’s needs for protein.

To help you understand amino acids as the building blocks of protein, we have gathered all the helpful information out there to satisfy your curiosity and help you gain a better understanding.

So let’s go ahead and dig deeper about amino acids, the building blocks of proteins in the following sections.

What are Amino Acids

What are Amino Acids

Amino acids are the organic compounds that compose proteins, and they are also found in other biomolecules. Out of the 20 types of amino acids that exist, nine of them are essential for humans as our bodies cannot produce them.

The other 11 are non-essential because our bodies can generate them from the food we eat. Although, eating a diet rich in amino acids can help the body perform better.

The term “amino acid” comes from the fact that these organic molecules have both an amine group (-NH2) and a carboxylic acid group (-COOH). When two amino acids join together, a peptide bond is formed between the nitrogen of one molecule and the carbon of the other, and a new molecule is created: a dipeptide.

Dipeptides are the simplest type of protein, and more complex proteins are composed of long chains of amino acids (polypeptides).

Amino acids can be classified into several groups according to their side chains or R-groups. The side chain is the part of the molecule that varies from one amino acid to another and confers different chemical properties to each.

There are 20 types of amino acids, 9 of which are essential amino acids that can’t be produced by the human body and have to be sourced from foods (more on this in the following sections).

The different amino acid classification is discussed in the next section.

Amino Acid Classifications

Amino Acid Classifications

The side chain can be hydrophobic (non-polar) or hydrophilic (polar), and those are the two main groups. There are also other groups, such as acidic, basic, and neutral amino acids.

Hydrophobic Amino Acids Or Non-Polar Amino Acids

The side chains of hydrophobic amino acids are also called non-polar and, as a result, do not interact well with water molecules. They tend to be found in the interior of proteins, away from the aqueous environment. Examples of hydrophobic amino acids include:

  • Alanine
  • Glycine
  • Isoleucine
  • Leucine
  • Methionine
  • Phenylalanine
  • Proline
  • Serine
  • Threonine
  • Tryptophan
  • Tyrosine

Hydrophilic Amino Acids or Polar Amino Acids

Hydrophilic Amino Acids also called Polar Amino Acids, have polar side chains and, as a result, interact well with water molecules. They tend to be found on the surface of proteins and play an important role in protein-protein interactions. Examples of hydrophilic amino acids include:

  • Asparagine
  • Aspartic acid
  • Cysteine
  • Glutamic acid
  • Glutamine
  • Histidine
  • Lysine
  • Arginine
  • Taurine

Acidic Amino Acids

Acidic amino acids have side chains that are called acidic, meaning they release H+ ions (protons) in solution. The most notable acidic amino acid is aspartic acid.

Aspartic acid’s side chain has a carboxylic group (-COOH) that readily releases protons in solution. The other acidic amino acids are:

  • Glutamic acid
  • Cysteine (under certain conditions)
  • Tyrosine (under certain conditions)

Basic Amino Acids

Basic amino acids have side chains that are called basic, meaning they accept H+ ions (protons) in solution. The most notable basic amino acid is lysine. Lysine’s side chain has an amine group (-NH2) that readily accepts protons in solution. The other basic amino acids are:

  • Arginine
  • Histidine
  • Tryptophan (under certain conditions)

Neutral Amino Acids

Neutral amino acids have side chains that are called neutral, meaning they are neither acidic nor basic. The most notable neutral amino acid is glycine. Glycine’s side chain is so small that it does not influence the pH of the solution. The other neutral amino acids are:

  • Alanine
  • Proline
  • Serine
  • Threonine

Types of Amino Acids According to Functions

Types of Amino Acids According to Functions

There are three main types of amino acids according to their functions in the body, conditional amino acids, essential, and nonessential amino acids. Let’s take a further look at the different types of amino acids as follows:

Essential Amino Acids

The essential amino acids are amino acids that your body cannot produce. Because your body cannot make essential amino acids, these essential amino acids must be sourced from food.

There are nine essential amino acids. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

The following are the functions of the essential amino group:

  • Histidine – regulates the sleep and wake cycle, and produces histamine a neurotransmitter for the immune system
  • Isoleucine- produces hemoglobin and regulates energy, aids in muscle metabolism
  • Leucine- promotes muscle repair and wound healing, also regulates blood sugar level
  • Lysine- produces elastin and collagen
  • Methionine- removes toxins from the body and aids in the absorption of zinc and selenium
  • Phenylalanine- forms melanin, dopamine, and norepinephrine
  • Threonine- metabolizes fat and produces collagen and elastin
  • Tryptophan – forms serotonin and regulates mood, appetite, and sleep
  • Valine- produces energy, repairs muscle, and helps in muscle growth

Nonessential Amino Acids

Unlike essential amino acids, nonessential amino acids are produced by your body naturally without you having to eat foods. The nonessential amino acids are alanine, asparagine, cysteine, glutamic acid, serine, tyrosine, aspartic acid, glycine, and proline.

The following are the functions of the nonessential amino group:

  • Alanine- regulates cholesterol and removes toxins from the body
  • Asparagine- facilitates the production of some neurotransmitters
  • Cysteine- produces collagen
  • Glutamic Acid- aids in digestion, metabolizes sugars and fats
  • Serine- forms glycine and cysteine, and also has an important role in the biosynthesis of pyrimidines and purines
  • Tyrosine- composes some neurotransmitters in the brain including dopamine, norepinephrine, and epinephrine
  • Aspartic Acid- produces energy and is used to treat chronic fatigue
  • Glycine – produces the antioxidant called glutathione and protects the liver from alcohol damage
  • Proline – aids in protein synthesis, aids in the healing of the skin and prevents wrinkles

Conditional Amino Acids

The conditional amino acids are a group of amino acids that become essential amino acids during certain times such as illness or stress. Examples of conditional amino acids include arginine, cysteine, glutamine, proline, serine, tyrosine, glycine, and ornithine.

The following are the functions of the conditional amino group:

  • Arginine
  • Cysteine
  • Glutamine
  • Proline
  • Serine
  • Tyrosine
  • Glycine
  • Ornithine

Amino Acids Functions and Benefits

Amino Acids Functions and Benefits

Proteins are important biomolecules that perform a variety of functions in the body.

Amino acids are the building blocks of proteins and, as a result, play an important role in the structure and function of proteins.

Proteins are involved in a wide range of functions in the body, including:

  • building and repairing tissues
  • enzymatic reactions
  • hormone production
  • immune system function
  • transporting molecules around the body
  • providing structural support

Essential amino acids are important for:

  • growth and development
  • repairing damaged tissue
  • maintaining muscle mass
  • regulating metabolism

Nonessential amino acids are important for:

  • metabolism
  • detoxification
  • maintaining a positive nitrogen balance
  • immune system function

Conditional amino acids are important for:

  • brain function
  • gut health
  • detoxification
  • energy production

Amino Acids and Protein Synthesis

Amino Acids and Protein Synthesis

Protein synthesis is the process by which the human body produces proteins from amino acids.

This process requires the participation of enzymes, ribosomes, and Messenger RNA (mRNA).

To help you understand protein synthesis better, first, you have to know about these major participants that form proteins as follows:

  • Enzymes- These are proteins that function to catalyze (accelerate) chemical reactions in the body. The role of enzymes is to break down the bonds between amino acids so that they can be rearranged by the ribosomes to form new proteins.
  • Ribosomes- These are small organelles in the cells that are responsible for assembling proteins from amino acids. The role of ribosomes is to arrange the amino acids in the order specified by the mRNA.
  • mRNA- This is a type of RNA that carries the genetic code from the DNA to the ribosomes. The role of mRNA is to provide the template for protein synthesis.

Sources of Essential Amino Acids

Sources of Essential Amino Acids

The essential amino acids, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine as mentioned earlier have to be sourced out from foods because this type of amino acid can’t be produced by the human body.

Food and Natural Sources for Essential Amino Acids

The following are the plant-based and animal food sources for the nine essential amino acids:

  1. Histidine – apples, dried bananas, pomegranates, alfalfa, beets, carrots, cucumber, celery radish, spinach, and garlic
  2. Isoleucine – yogurt, beef, tuna, haddock, cod, sesame seeds, lentils, spirulina, seaweed, and wheat
  3. Leucine – beef, lamb, poultry, collagen, gelatin, sunflower seeds, pistachios, wheat germ, peanuts, spirulina, and brown rice
  4. Lysine – red meat, lima beans, dried apricots, avocados, beetroots, mangoes, leeks, potatoes, and peppers
  5. Methionine – shrimp, beef, lamb, salmon, tuna, tofu, beans, lentils, brazil nuts, spirulina, wheat germ
  6. Phenylalanine – eggs, cheese, yogurt, beef, lamb, pork, pumpkin seeds, tofu, quinoa, wild rice, and wheat germ
  7. Threonine – collagen, gelatin, cheese, lamb, beef, pork, flaxseeds, wheat germ, cashews, almonds, tofu, and sunflower seeds.
  8. Tryptophan – cheese, red meats, turkey, eggs, fish, yogurt, milk, chocolate, pepitas, chickpeas, bananas, spirulina, and peanuts.
  9. Valine – soy products, dairy products, red meats, mushrooms, peanuts, and low-fat yogurt.

Supplements for Amino Acids

Aside from the natural sources of the nine essential amino acids, there are protein supplements nowadays that contain all the essential amino acids needed by the body.

Protein supplements come in different forms, such as whey protein, casein protein, soy protein, egg protein, pea protein, hemp protein, and rice protein.

There are also amino acid supplements that come in powder or capsule form. These supplements are usually taken before and after workout sessions to help the body recover faster from muscle fatigue and to promote muscle growth.


Amino acids as the building blocks of proteins are important nutrients needed by the body to perform various functions such as growth and development, repair of damaged tissues, and the production of enzymes and hormones.

There are a variety of animal and plant-based sources for essential amino acids for your protein needs. The other option is to source your proteins from supplements that contain the needed amino acids by your body.

We hope this article has helped you understand the role of amino acids in protein synthesis and the importance of including them in your diet.

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Article by Albie C.

I'm Albie, a personal health and fitness writer from the UK. I have a degree in personal health and fitness, so I know my stuff! I love writing about all things health and fitness related, but also enjoy writing about other topics that interest me. I love living a healthy lifestyle and helping others do the same. I hope to inspire people to lead healthier lives through my writing.