By: by Amino Science
Amino acids are the building blocks of protein, and proteins are, in turn, the building blocks of our muscles, cartilage, bones, skin, and blood. Crucial to life, amino acids also synthesize hormones and neurotransmitters, and help protect us from infection and illness. We can’t live without them, so let’s spend some time understanding these biological heroes. We’ll review the importance of protein and amino acids, their structures, and all the different types, from essential amino acids to ketogenic amino acids and everything in between.
We’ll get into the structure of amino acids in detail later on, but to understand the role they play as the building blocks of protein it’s helpful to understand how they form proteins.
Scientists have identified approximately 500 naturally occurring amino acids, of which only 20 are used to make proteins in the human body, earning them the sobriquet proteinogenic amino acids.
These 20 amino acids link together in varying combinations to form different types of protein. That’s the simple how of it that will suffice for the moment.
Proteins make up every cell in our bodies, but just as proteins are made up of a different mix of amino acids, they also perform different functions.
Some proteins give structure to our hair, skin, nails, cartilage, and tissues. Others are used to make enzymes that catalyze the biochemical reactions in our bodies. Still others form hormones that transmit information between cells, organs, and tissues, while many play a part in the growth and maintenance of muscle.
Proteins help normalize fluid balance and pH levels, and even strengthen immune health by forming antibodies, or immunoglobulins, that defend against bacteria and viruses.
And amino acids are the key to it all.

Protein is a macronutrient like fat and carbohydrates, but unlike fat and carbs, protein cannot be stored in the body. It’s converted into glucose or triglycerides and used to fuel energy or build up your energy reserves. Any excess is excreted by the kidneys as urea. While you don’t want to consume too much protein, as doing so can overtax your kidneys, agitate the body’s pH levels, and increase calcium excretion which can lead to osteoporosis, you also must be sure to eat enough protein to satisfy your body’s needs.
Experts hold that 0.8 grams of protein per 2 pounds of body weight meets the minimum protein requirements, but bodybuilders, athletes, older adults, and the infirmed have much higher protein needs, and can benefit from supplemental support.
Before we cover the best way to meet your protein needs, let’s figure out which amino acids are most important to your diet.
The 20 proteinogenic amino acids in the standard genetic code are divided into three main categories that you may already be familiar with: essential amino acids, nonessential amino acids, and conditionally essential amino acids.
The essential amino acids can’t be produced in the body and you must get them from your diet and/or as part of a targeted supplement.
The nine essential amino acids are:
The essential amino acids all play a role in protein synthesis, but let’s get to know their specific functions a little better.
These amino acids are just as important to health as the essential amino acids, but your body can produce them, so they aren’t an essential component of your diet. They are:
Each has a unique set of responsibilities in the body.
Also referred to as semi-essential amino acids, conditionally essential amino acids are the nonessential amino acids that become essential under conditions of stress, injury, or illness because the body has trouble producing them. In these instances, dietary support is required.
The 7 nonessential amino acids that can become semi-essential amino acids are:
So, what’s the best way to meet your protein needs? By eating a diet rich in amino acids, especially complete proteins that contain a sufficient amount of all nine of the essential amino acids.
Complete proteins include:
If, however, you are battling an illness or injury, your protein needs are unlikely to be met through diet alone. Likewise, if you are an older adult and thereby prone to age-related muscle decline, your body isn’t responding to the muscle-building cues of essential amino acids as readily, and you would benefit from additional support. And if you’re looking to build muscle, you’re definitely going to want to bolster your resistance training program with an essential amino acid supplement.
Low in calories and high in the nutrients needed to increase lean body mass, speed healing, and protect against infections, 15 grams of supplemental essential amino acids a day can shore up any nutritional gaps and make sure you’re feeding your body the amino acids it needs to recover quickly from stress and thrive.
Check out our patented essential amino acid blends, developed by the top minds in amino acid research and formulated to the precise ratio to help you treat your health needs or reach your performance goals.
We’ve gained a general understanding of the role the building blocks of protein play in your body, the specific functions of each, and the importance of supplying your body with the essentials. For all you science buffs and MCAT students out there, let’s go a little deeper into the chemistry of amino acids.
Amino acid is the abbreviated version of α-amino (alpha-amino) carboxylic acid. The long version can help explain the fundamental structure of amino acids.
Almost every amino acid has a primary amino group (―NH2) and an acidic carboxyl group (―COOH) that are attached to each other by way of a central carbon (C) atom called the α-carbon (alpha-carbon).
The α-carbon atom is typically bonded with a hydrogen atom and the R group. The R group is the distinguishing feature of every amino acid and determines aspects such as size, polarity, and pH. The R group is what makes the amino acid unique.
There are some outliers. Proline’s R group, for instance, is bonded to both its central carbon atom and its amino group, and glycine’s single hydrogen side chain in place of an R group makes it a structural standout, but we can pretty much count on this fundamental structure when analyzing amino acids.
Check out the visual below to see how these bonds form amino acids.

Amino acids link together through peptide bonds, a type of covalent bond that forms in reaction to the amino group of one amino acid coming into contact with the carboxylic group of another amino acid. These peptide bonds form a polypeptide chain and represent the primary structure, which is the simplest level of protein structure.
Secondary structure is determined by the interactions between the amino acids’ hydrogen bonds and the formation of beta barrels and alpha helixes.
Tertiary structure accounts for an overall folding of the entire polypeptide chain and the interactions between the secondary structures to form a specific 3D shape.
Many proteins stop there, but others such as hemoglobin will go on to a quaternary structure made up of multiple polypeptide chains.
The amino acids can be separated into many different types based on their polarity, pH level, side chain type, and the locations of their core structural functional groups.
Let’s talk first about functional groups, which are the R groups that determine the exact chemistry of each protein. Of the 20 standard amino acids 6 have hydrocarbon R groups, 7 have neutral groups, and 6 have acid or base R groups. And then there’s glycine, with its single hydrogen atom.
From there, amino acids can be classified according to their pH. For instance, glutamic acid and aspartic acid are acidic with a low pH, while arginine, histidine, and lysine are basic with a high pH.
Polarity refers to how the amino acid responds to water: does it repel water (nonpolar) or does it attract water (polar)?
Polar amino acids, which have atoms from different elements, tend to have hydrophilic side chains, meaning they like water. These amino acids include:
They have at the ready at least one nitrogen, oxygen, or sulfur atom waiting to pair with water.
Nonpolar amino acids, which have atoms from the same elements, tend to be hydrophobic and resist water. These amino acids include:
We’ve already discussed different types of amino acids, such as essential amino acids, the subgroup BCAAs, and sulfuric acids like methionine and cysteine. Other categories of interest include glucogenic amino acids, ketogenic amino acids, and aromatic amino acids.
The glucogenic amino acids are distinct in that they convert to glucose through gluconeogenesis. During gluconeogenesis, amino acids in the liver are changed into alpha keto acids and then into glucose. These are:
Instead of being converted into glucogenic amino acids, these amino acids become ketone bodies. Leucine and lysine are the true ketogenic amino acids, but there are five others that can be both ketogenic and glucogenic according to need.
Ketone bodies are an alternative source of energy for the brain and are the coveted byproduct of low-carb diets, which means there may be some benefit of increasing your intake of ketogenic amino acids.
There are just three aromatic amino acids―phenylalanine, tyrosine, and tryptophan. They feature a characteristic aromatic ring with three double bonds on their side chains and can absorb ultraviolet light.
If you’re curious about the chemistry, then check out our more comprehensive articles on:
And if you’d like to start optimizing your health with amino acids, then the first step is to learn more about our patented amino acids blends formulated from decades of research.
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