In this chapter, we focused on the genetic code and the transcription of genetic information stored in DNA into complementary RNA molecules. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: How were the specific sequences of triplet codes determined experimentally?

Key Concepts

Genetic Code

The genetic code is a set of rules that defines how the information encoded in DNA is translated into proteins. It consists of triplet codons, each made up of three nucleotides, which correspond to specific amino acids. Understanding the genetic code is essential for deciphering how sequences of DNA dictate the structure and function of proteins.

Transcription

Transcription is the process by which the genetic information in DNA is copied into messenger RNA (mRNA). This process involves the enzyme RNA polymerase, which binds to the DNA and synthesizes a complementary RNA strand. Transcription is a critical step in gene expression, as it allows the genetic code to be translated into functional proteins.

Experimental Determination of Codons

The specific sequences of triplet codes were determined through various experimental methods, including the use of synthetic RNA and ribosomes. Researchers like Marshall Nirenberg and Har Gobind Khorana conducted experiments that involved creating artificial mRNA sequences and observing the resulting protein synthesis, which helped identify which codons corresponded to which amino acids.