Question

Describe how a mixed copolymer experiment is performed

Answer 1

Solution

• This experiment was carried out by Nirenberg and Matthaei experiment in may 1961.
• The experiment deciphered the first of the 64 triplet codons in the genetic code by using nucleic acid homopolymers to translate specific amino
• In the experiment, an extract from bacterial cells that could make protein even when no intact living cells were present was prepared.
• Adding an artificial form of RNA consisting entirely of uracil-containing nucleotides (polyuridylic acid or poly-U), to this extract caused it to make a protein composed entirely of the amino acid phenylalanine.
• This experiment cracked the first codon of the genetic code and showed that RNA controlled the production of specific types of protein.
• They created synthetic RNA molecules outside the bacterium and introduced this RNA to the E. coli system. The experiments used mixtures with all 20 amino acids.
• For each individual experiment, 19 amino acids were "cold" (nonradioactive), and one was "hot" (radioactively tagged with 14C so they could detect the tagged amino acid later).
• They varied the "hot" amino acid in each round of the experiment, seeking to determine which amino acids would be incorporated into a protein following the addition of a particular type of synthetic RNA.