What Are Amino Acids (function, What They Are for and Types)

Amino acids are monomers that form the basis of vital proteins for the proper functioning of our body.

Amino acids are composed of an amino group (NHtwo) which is a basic radical, and a carboxyl group (COOH) which is an acid group. The proteins of living beings are composed of the combination of 20 important amino acids for the organism.

The union of 2 amino acids is due to a peptide bond between the carbon of the carboxyl group of the first amino acid and the nitrogen of the amino group of the second amino acid. This binding releases a water molecule and forms what is called a peptide.

The ligation of 2 or more peptides is called a polypeptide and, in turn, 1 or more united polypeptide chains with a certain amino acid sequence and three-dimensional structure form a functional and mature protein. Depending on their structure, amino acids can be differentiated into the forms of L and D.

Amino acid function

Amino acids fulfill various functions that are basic for the vital metabolic process of the organism, since they are the basis of proteins.

In this sense, amino acids share many of the functions of proteins, such as enzymatic and hormonal. Its most important functions include:

  • Nutrient transport.
  • Repair or growth of body tissues.
  • Storage of nutrients such as water, proteins, minerals, vitamins, carbohydrates and fats.
  • They can provide energy.
  • Maintains the balance of acids in the body.
  • Allows muscle contraction.
  • It allows the proper development and functioning of organs and glands.
  • They are involved in the repair of tissues, skin and bones, as well as in the healing of wounds.
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Amino acid structure

amino acid structure

Amino acids are formed, in general, by a carbon, a carboxyl group (COOH), an amino group (NHtwo), a hydrogen, and a functional group called the side chain or R group.

In this sense, the carboxyl group is attached to the amino group through the same carbon (central atom), called alpha carbon. This carbon is associated with a hydrogen and a group R, which will determine the chemical behavior of the amino acid.

At a biological level, the 20 amino acids from which proteins are formed have, therefore, different side chains. The simplest side chain is the one that constitutes the amino acid glycine, whose R group consists only of a hydrogen molecule.

The sequence and type of amino acids needed to synthesize proteins on the ribosomes are determined by the information contained in the messenger RNA (mRNA or mRNA).

In this sense, amino acids are essential elements for the creation of polypeptide chains (future proteins) that are translated by ribosomes through the work between mRNA and transfer RNA (tRNA).

types of amino acids

There are a large number of amino acids, approximately 250 amino acids that are not part of proteins and 20 amino acids that make up proteins, also known as alpha-amino acids.

The 20 amino acids that make up proteins are classified according to:

  • the type of side chain or R group (hydrocarbons, neutral, acid or base),
  • its chemical behavior (acidic, basic, polar or nonpolar), and
  • whether or not it is synthesized by the human body (essential or non-essential).

However, regardless of their classification, all amino acids are important for the human body and for maintaining good health.

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Essential amino acids

Essential amino acids are those that the human body is not capable of generating and are obtained through food. Of the 20 amino acids, 10 are the essential ones: leucine, lysine, methionine, isoleucine, histidine, arginine, phenylalanine, threonine, valine and tryptophan.

non-essential amino acids

There are 10 non-essential amino acids and they are those that the body can synthesize. They are of great importance because they generate the proteins necessary for the proper functioning of the organism. Non-essential amino acids are: glycine, alanine, proline, serine, cysteine, glutamine, aspartic acid, glutamic acid, asparagine, and tyrosine.

the 20 amino acids

The 20 amino acids whose combinations constitute the proteins necessary for the proper biochemical functioning of our organisms are called alpha-amino acids.

Below are the 20 alpha-amino acids together with their classification, according to the type of side chain or R group (hydrocarbons, neutral, acid or base), its chemical behavior (acid, basic, polar or nonpolar) and if it is synthesized or not by the human body (essential or non-essential).

20 amino acids

See also Proteins and Biomolecules.