Meaning: Francis Crick, the renowned molecular biologist and co-discoverer of the structure of DNA, posed a fundamental question in the field of genetics with his inquiry into the division of the base sequence into codons. This statement reflects his curiosity about the underlying mechanisms by which the genetic information encoded in DNA is translated into functional proteins. To understand the significance of this quote, it is essential to delve into the concepts of genetic coding, the structure of DNA, and the process of protein synthesis.

Crick's inquiry into the division of the base sequence into codons is rooted in the nature of DNA, the molecule that serves as the repository of genetic information in all living organisms. DNA is composed of a double helix structure, consisting of two long chains of nucleotides twisted around each other. Each nucleotide comprises a phosphate group, a sugar molecule, and one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G). The sequence of these bases along the DNA strand forms the genetic code, which determines the specific traits and functions of an organism.

The process of translating the genetic information encoded in DNA into proteins involves the intermediary molecule known as messenger RNA (mRNA). This process, called transcription, occurs in the cell's nucleus, where a specific segment of DNA is transcribed into mRNA by an enzyme called RNA polymerase. The mRNA carries the genetic code from the nucleus to the cytoplasm, where it serves as a template for protein synthesis during the process of translation.

The division of the base sequence into codons is crucial for understanding how the genetic code is read and translated into proteins. A codon is a sequence of three nucleotides in mRNA that corresponds to a specific amino acid or serves as a start or stop signal for protein synthesis. The genetic code is degenerate, meaning that most amino acids are encoded by multiple codons. This redundancy provides robustness and flexibility to the genetic code, allowing for minor errors or mutations to be tolerated without significantly altering the resulting protein.

Crick's question about the division of the base sequence into codons highlights the apparent lack of explicit markers or indicators in the DNA backbone to delineate the boundaries of codons. Unlike the regular and repetitive structure of the DNA double helix, which forms the basis of its stability and functionality, the grouping of bases into codons is not directly discernible from the physical structure of the molecule. This observation underscores the intricate and complex nature of the genetic code and the mechanisms by which it is deciphered and translated by the cellular machinery.

To address Crick's inquiry, researchers have delved into the field of molecular genetics and bioinformatics to decipher the rules and principles governing the division of the base sequence into codons. Through experimental studies and computational analyses, scientists have elucidated the genetic code and the specific codon assignments for each amino acid. These efforts have revealed the existence of codon-anticodon interactions, where the three-nucleotide codon in mRNA is recognized by a complementary sequence, called the anticodon, in transfer RNA (tRNA) molecules.

The process of translation, which involves the coordinated action of ribosomes, tRNAs, and various protein factors, ensures that the codons in mRNA are accurately read and matched to the corresponding amino acids, leading to the synthesis of functional proteins. The division of the base sequence into codons is thus intricately linked to the precise and efficient decoding of the genetic information, allowing for the synthesis of a diverse array of proteins that are essential for the structure and function of cells.

In conclusion, Francis Crick's inquiry into the division of the base sequence into codons reflects the profound mystery and complexity of the genetic code and the mechanisms by which it is translated into proteins. The division of the base sequence into codons is a fundamental aspect of genetic coding, with implications for our understanding of molecular genetics, protein synthesis, and the regulation of gene expression. By exploring the intricacies of the genetic code and the processes underlying protein synthesis, researchers continue to unravel the mysteries of DNA and its central role in the biology of life.