Question

Which of the following were used in the efforts to decipher the genetic code?

a. Triplet-binding assays to determine which transfer RNAs bind to specific codons
b. Cell-free translation experiments using synthetic messenger RNAs
c. In vitro assays of specific tRNA and mRNA binding interactions
d. Cell-free translation experiments using RNA copolymers with repeating patterns of nucleotides
e. In vitro transcription assays to show which types of mRNA are produced

Answer 1

Deciphering the genetic code involved triplet-binding assays, cell-free translation experiments with synthetic mRNAs and RNA copolymers, in vitro tRNA and mRNA binding interaction assays, and transcription assays that were less directly involved.

Step-by-step explanation:

The efforts to decipher the genetic code involved several key experimental approaches:

1. Triplet-binding assays to determine which transfer RNAs (tRNAs) bind to specific codons. This assay helped elucidate the connection between a tRNA molecule and its corresponding mRNA codon.
2. Cell-free translation experiments using synthetic messenger RNAs (mRNAs). By translating these synthetic mRNAs in vitro and sequencing the resulting proteins, scientists were able to determine which codons correspond to which amino acids.
3. In vitro assays of specific tRNA and mRNA binding interactions contributed to understanding the specificity of the genetic code.
4. Cell-free translation experiments using RNA copolymers with repeating patterns of nucleotides allowed scientists to identify which sequences of nucleotides resulted in the synthesis of specific proteins.
5. In vitro transcription assays were used less directly, to show which types of mRNA are produced under certain conditions, but this process is more related to gene expression than the deciphering the genetic code itself.

Overall, these methods were vital in piecing together the codon assignments of the genetic code, leading to our current understanding that 64 triplet codons in mRNA specify 20 amino acids and three stop signals, creating a degenerate code wherein some amino acids are coded for by more than one triplet.