Question

How does the central dogma of biology relate to the idea that structure defines function?

Answer 1

Central dogma of biology states that the genetic information present in DNA is transcribed into RNA, which is transportable cassette. The information in RNA is the translated to protein or a number of proteins.

DNA is double stranded with each strand made up of the phosphate linked to the deoxyribose sugar which in turn is linked to nitrogen base. The nitrogen bases in one strand are linked to nitrogen bases of other strand by hydrogen bonds. Adenine base pairs with thymine and guanine base pairs with cytosine. Only the 3’ to 5’ strand of DNA can act as the template strand to produce the 5’ to 3’ mRNA strand during transcription. Thus, the structure of DNA or the sequence of nucleotides present in DNA is responsible for the sequence of codons in the mRNA.

Proteins determine the structure and function of all cells in the body. Proteins have four levels of structure-primary, secondary, tertiary and quaternary. The primary structure is the sequence of amino acids that are determined from the codon sequences (set of triplet nucleotides) present in mRNA and in turn present in DNA. The primary determinant of the proteins structure is the primary structure which is sequence of amino acid. This sequence of codons determines the sequence of amino acids in the protein during translation. The codon sequence will determine which tRNA is attached to codon as anticodon sequence is complementary to codon sequence. Thus, it is ultimately the DNA structure that determines the protein structure. The function of the protein depends to the most extent on primary structure. It is the primary structure that determines the secondary, tertiary and quaternary structure of the protein. The final structure of protein will determine what function the protein has in the cell- whether it is a structural protein, enzyme etc. The function of the protein ultimately determines the function of the organism. Thus, the central dogma of biology indicates that structure of DNA is responsible for function of protein (ultimately organism functions).