Genetic Code: Definition, Function and Types of Mutations

It is the code that our body uses to convert the instructions contained in our DNA into the essential materials of life.

It is usually formed using the “codons” found in the mRNA since the mRNA is the messenger that transports information from the DNA to the site of protein synthesis.

Everything in our cells is finally built based on the genetic code. Our genetic information, that is, the data transmitted from parents to children, is stored in DNA.

That DNA is used to build RNA, proteins, and finally, cells, tissues, and organs.

As the binary code, DNA uses a chemical language with only a few letters to store information in a very efficient way. While the binary uses only ones and zeros, the DNA has four letters that are the four nucleotides:

  • Adenine.
  • Citosina.
  • Guanine.
  • Timing/Uracil.

Thymine and uracil are very similar, except that “thymine” is a little more stable and is used in DNA. Uracil is used in RNA and has all the same properties as thymine, except it is a little more prone to mutate.

This does not matter in RNA since new copies of RNA can be produced from DNA. Most RNA molecules are intentionally destroyed by the cell shortly after production so that the cell does not waste resources producing unnecessary proteins from old RNA molecules.


Together, these four letters of A, C, G, and T / U are used to “spell out” coded instructions for each amino acid, as well as other instructions such as “start transcription” and “stop transcription.”

The instructions to “start,” “stop,” or for a given amino acid are “read” by the cell in blocks of three letters called “codons.”

When we speak of “codons,” we usually refer to codons in mRNA: the “messenger RNA” made by copying the information in the DNA.

For that reason, we talk about codons made of RNA, which uses uracil instead of the original DNA code that uses thymine.

Each amino acid is represented in our genetic instructions by one or more codons.

One of the most remarkable pieces of evidence of the common ancestor of all life on earth of a single ancestor is that all organisms use the same genetic code to translate DNA into amino acids.

Some minor exceptions are found, but the genetic code is sufficiently similar in all organisms that when a gene from a plant or jellyfish is injected into a mammalian cell, for example, the mammalian cell will read the same gene way and build the same product as the original plant or jellyfish!

The function of the genetic code

The genetic code allows cells to contain a vast amount of information.

Consider this: a microscopically fertilized egg, following the instructions contained in its genetic code, can produce a human being with a personality and behaviors similar to those of their parents. There’s a lot of information there!

The development of the genetic code was vital because it allowed living beings to produce the products necessary for their survival reliably and passed instructions on how to do the same to the next generation.

When a cell tries to reproduce, one of the first things it does is make a copy of its DNA. This is the “S” phase of the cell cycle, which means the “Synthesis” of a new copy of the cell’s DNA.

The information encoded in the DNA is conserved by the specific pairing of the DNA bases with each other. Adenine will only join with Timina, Citosina, Guanina, etc.

When a cell wants to copy its DNA, all it has to do is separate the two strands of the double helix and align the nucleotides with which the existing DNA bases “want” to pair.

This specific base-pairing ensures that the new partner’s strand will contain the same sequence of base pairs, the same “code” as the previous one. Each resulting double helix has an old DNA strand paired with a new strand of DNA.

These new double helices will be inherited by two daughter cells. When the time comes for these daughter cells to reproduce, each strand of these new double helixes acts as a template for a new double helix.

When the time comes when a cell “reads” the instructions contained in its DNA, it uses the same principle of peer-specific linking. RNA is very similar to DNA, and each RNA base binds specifically to a DNA base. Uracil binds to adenine, cytosine to guanine, etc.

This means that, like DNA replication, the information in the DNA is transferred precisely to the RNA. The resulting RNA chain is composed of the bases that bind specifically to the bases in the DNA.

Sometimes, the RNA chain itself can be the final product. The structures made of RNA play essential functions in ourselves, such as the assembly of proteins, the regulation of gene expression, and the catalysis of protein formation.

Some scientists think that the first life on earth could have been composed chiefly of RNA.

This is because RNA can store information in its base pairs like DNA, but it can also perform enzymatic and regulatory functions.

In most cases, however, the RNA becomes transcribed into a protein. Using the amino acid “building blocks of life,” our cells can build almost protein machines for virtually any purpose, from muscle fibers to neurotransmitters and digestive enzymes.

In protein transcription, the codons of RNA transcribed from the DNA are “read” by a ribosome.

The ribosome finds the appropriate transfer RNA (tRNA) with “anti-codons” that are complementary to the codons in the messenger RNA (mRNA) that has been transcribed from the DNA.

Ribosomes catalyze the formation of peptide bonds between amino acids as they “read” each codon in the mRNA. At the end of the process, it has a chain of amino acids specified by the DNA, that is, a protein.

In turn, other building blocks of life, such as sugars and lipids, are created by proteins. In this way, the information contained in the DNA is transformed into all the materials of life using the genetic code!

Types of genetic mutations

Because the genetic code contains information for life, errors in an organism’s DNA can have catastrophic consequences.

Errors can occur during DNA replication if the wrong base pair is added to a DNA strand, if a base is omitted, or if an additional command is added.

These errors can be helpful in rare cases: the “wrong” version of DNA can work better than the original or have a completely new function! In that case, the latest version may be more successful, and your provider may outperform the operators of the previous version in the population.

This extension of new features in an entire population is how evolution works.

Silent mutations and redundant coding

In some cases, genetic mutations may not affect the final product of a protein. As seen in the previous table, most amino acids are connected to more than one codon.

Glycine, for example, is encoded by the codons GGA, GGC, GGG, and GGU. A mutation that results in the wrong nucleotide being used for the last letter of the glycine codon then would not matter.

A codon that starts at “GG” will still encode glycine, regardless of which letter was last used.

It is believed that the use of multiple codons for the same amino acid is a mechanism that evolved to minimize the possibility of a small mutation causing problems for an organism.

Mutation without meaning

In a nonsense mutation, they are substituting a base pair for an incorrect base pair during DNA replication results in the use of the wrong amino acid in a protein.

This can have a negligible effect on an organism, or a large one, depending on how essential the amino acid is for the function of its protein and in which it is made.

This can be thought of as furniture construction. How bad would it be if you used the wrong piece to screw the leg of a chair into place?

If you used a screw instead of a nail, the two are probably similar enough so that the leg of the chair stays lit, but if you try to use, for example, a cushion to attach the portion to the chair, your chair will not It will work very well.

A nonsense mutation can result in an enzyme almost as good as the standard version or an enzyme that does not work.

A nonsense mutation occurs when the incorrect base pair is used during DNA replication but when the resulting codon does not encode the wrong amino acid.

Instead, this error creates a stop codon or other indecipherable information for the cell. As a result, the ribosome stops functioning in that protein, and all subsequent codons are not transcribed.

The nonsense mutations lead to incomplete proteins, which can work very poorly or not. Imagine if you stopped building a chair in half!


One or more DNA bases are not copied during DNA replication in a deletion mutation. Elimination mutations come in various sizes: a single pair of commands may be missing, or a large piece of a chromosome may be missing!

The minor mutations are not always less harmful. The loss of only one or two bases can modify the reading frame that damages a crucial gene.

Conversely, more extensive deletion mutations can be fatal, resulting in a disability, as in DiGeorge syndrome and other conditions that result from the removal of part of a chromosome.

The reason for this is that the DNA looks a lot like the source code of the computer; a piece of code can be crucial for the system to turn on, while other parts of the code could ensure that a website looks good or loads quickly.

Depending on the function of the code fragment that is deleted or modified, a small change can have catastrophic consequences, or a seemingly considerable alteration of the code one can result in a system that is a bit imprecise.


An insertion mutation occurs when one or more nucleotides are mistakenly added to a growing DNA strand during DNA replication. Rarely long stretches of DNA can be added incorrectly in the middle of a gene.

Like a nonsense mutation, the impact of this may vary. Adding an unnecessary amino acid to a protein can make the protein only slightly less efficient, or it can paralyze it.

Consider what would happen to your chair if you added a random piece of wood that the instructions did not require. The results can vary greatly depending on the size, shape, and location of the extra work!


A duplication mutation occurs when a segment of DNA is accidentally replicated two or more times. Like the other mutations listed above, these may have mild effects or be catastrophic.

Imagine that your chair has two backs, two seats, or eight legs. Although a bit strange or uncomfortable, a minor duplication and the chair can still be usable. But if the chair had, for example, six seats joined together, it could quickly become useless for its intended purpose!

Mutation with scrolling reading pattern

A mutation of the reading frame is a subtype of insertion, deletion, and duplication mutations.

In a mutation of the reading frame, one or two amino acids are deleted or inserted, resulting in a displacement of the “frame” used by the ribosome to indicate where a codon stops and the next begins.

This type of error can be hazardous because it causes all the codons that occur after the mistake to be misinterpreted. Typically, each amino acid added to the protein after the mutation of the reading frame is incorrect.

Imagine if you were reading a book, but at some point during the writing, an error occurred, so that each subsequent letter changed one letter later in the alphabet.

A word supposed to read “letter” would suddenly become “must.” This is approximately what happens in a mutation of the reading frame.