Before the genetic code was actually known, Francis Crick predicted that it was degenerate. What piece of evidence led him to make this prediction?
A)All proteins looked the same.
B)All proteins were made of amino acids.
C)He noted that the base composition of the DNAs of various bacteria varied greatly while the amino acid composition of their proteins varied much less.
D)He noted that the base composition of the DNAs of various bacteria varied little while the amino acid composition of their proteins varied greatly overall.
E)The code was non-overlapping.

Question

Quizplus · Accepted Answer

Crick observed that the base composition (the proportion of adenine, thymine, cytosine, and guanine) of DNA from different bacteria varied significantly, while the amino acid composition of their proteins was much more conserved. This suggested that multiple codons (sequences of three DNA or RNA nucleotides) could code for the same amino acid, leading to the prediction that the genetic code was degenerate, meaning that a single amino acid could be encoded by more than one codon.

Before the Genetic Code Was Actually Known, Francis Crick Predicted