The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons (see Figure 13.7). An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:

Amino Acid       Percentage
  Met                        2
  Cys                        2
  Gln                         5
  Pro                         5
  Arg                         5
  Ile                           6
  Glu                         7
  Ala                         8
  Leu                        10

Devise a way to graphically compare the two sets of information (data).

Key Concepts

Degeneracy of the Genetic Code

The genetic code is described as degenerate because multiple codons can encode the same amino acid. This redundancy allows for some mutations to occur without affecting the protein produced, providing a buffer against potential errors in DNA replication or transcription. Understanding this concept is crucial for analyzing how the frequency of amino acids relates to their codon usage.

Amino Acid Frequency in Proteins

Amino acid frequency refers to how often specific amino acids appear in proteins, which can vary significantly among different organisms and proteins. In the context of E. coli, the provided percentages indicate the relative abundance of each amino acid, which can be correlated with the number of codons that encode them. This relationship is essential for evaluating whether the genetic code is optimized for efficient protein synthesis.

Graphical Data Representation

Graphical data representation involves using visual formats, such as charts or graphs, to compare and analyze data sets effectively. In this case, one could use bar graphs or scatter plots to illustrate the relationship between the number of codons for each amino acid and their frequency in E. coli proteins. This visual approach aids in identifying patterns and correlations that may not be immediately apparent from raw data.