Why is the DNA information coded in "threes"?
The DNA information is coded in "threes" because of the way DNA is structured. DNA is composed of a sequence of nucleotides, which are molecules that make up the genetic code. Each nucleotide consists of a nitrogenous base (adenine, thymine, cytosine, or guanine), a sugar molecule, and a phosphate group.
The specific order of these nitrogenous bases within the DNA strand is what carries the genetic information. It is the sequence of bases that determines the instructions for building and maintaining an organism.
Now, the key aspect here is that the genetic code is read in groups of three nucleotides, known as codons. Each codon represents a specific amino acid, the building blocks of proteins. There are a total of 64 unique codons possible (4 bases raised to the power of 3), but only 20 different amino acids exist. This means that some amino acids can be encoded by multiple codons. For example, the amino acid leucine can be encoded by six different codons.
This three-letter code system makes the genetic code more efficient and robust. By having multiple codons represent the same amino acid, there is redundancy or degeneracy in the system. This redundancy provides a buffer against errors during DNA replication or mutation, as a change in one base may not necessarily result in a change in the encoded amino acid.
So, the DNA information is coded in "threes" because that is the fundamental unit at which the genetic code is read and translated into proteins, which are crucial for the structure and function of living organisms.