A triplet is a unit of reading information from a nucleic acid that is recognized during translation on the ribosomes of a cell. DNA nucleotides carry information about the encoded protein, so it is important to read it correctly, without errors and inaccuracies. Therefore, tripletiness as one of the properties of the genetic code helps to convey the programmed sequence of amino acids of the future protein to the maximum degree possible.
A triplet is a unit of DNA information.
Nucleic acids are biopolymers whose monomers are nucleotides. The latter form a continuous chain of genetic information, the reading of which occurs at the stage of transcription. Already here, a DNA reading frame is determined, according to which the synthesis of messenger RNA occurs , and therefore, the starting and finishing triplets.
The reading frame should not change during the transcription, as this can lead to unpleasant consequences in the synthesis of protein. For example, a peptide can be shortened, have a completely different amino acid sequence, become potentially dangerous for the cell.
The need for triplets arises at the stage of translation - direct reading of information from RNA with the formation of the primary structure of the protein molecule. And here the question arises: so what is a triplet? Why is a cell needed and what is its biological role?
The value of triplet in protein biosynthesis
The information programmed into DNA and then into RNA is clearly structured into separate parts. A continuous sequence of nucleotides must somehow be broken down into functional segments, along which protein biosynthesis is possible. Triplet - this is the functional unit and basis of the synthesis of the polypeptide, without which the reading of information from a nucleic acid is impossible.
A triplet, or codon, is three consecutive nucleotides that stand behind each other. Each of them encodes a single amino acid, which is delivered via tRNA to ribosomes during protein biosynthesis.
It is interesting that several different codons can correspond to the same amino acid at once. However, one such triplet encodes its only amino acid. The degeneracy and uniqueness of the genetic code is another way by which the synthesis of protein molecules proceeds in the cell. For example, the amino acid methionine is encoded only by a single AUG codon (adenine, uracil, guanine, respectively). And valine, in turn, is programmed by several triplets at once, and among them GUU, GUTs, GUA and GUG.
What nucleotides are part of a triplet?
A triplet of DNA is a set of three consecutive nucleotides that stand next to each other. The boundaries of each codon are strictly fixed so that the reading frame does not shift and a defective and irregular protein subsequently forms. Triplet is three nucleotides in biology, however nucleic acids consist of several types of monomers. What are the nucleotides in DNA and RNA?
All nucleic acid monomers are divided into two large groups: purine and pyrimidine. Purine bases are a group of nucleotides that include adenine and guanine. Their distinctive feature is that the molecule consists of two carbon rings.
Another group is nucleotides, the molecular skeleton of which is formed by only one ring. These monomers include cytosine, as well as thymine (in DNA) and uracil (instead of thymine in RNA).
Is the codon and triplet the same thing?
The term “codon” is used to describe the translation process, when information about those amino acids that should be part of a new protein is read from an RNA molecule. Triplet is a broader concept, and it is used to describe the reading frame of RNA, and in some cases, DNA. Although it’s difficult to say in practice where the boundary between two adjacent triplets is, in theory, this line is constant and does not change in theory.
In essence, the codon and the triplet are one and the same. The only difference is when the concept of “codon” is used, and when is “triplet”. If the former can be heard in the description of translation, the latter is used to denote the three nucleotides in the nucleic acids.