Genetics: Analysis and Principles 4th Edition by Robert Brooker

Exercise 6

The wobble rules for tRNA-mRNA pairing are shown in Figure 13.12. If we assume that the tRNAs do not contain modified bases, what is the minimum number of tRNAs needed to efficiently recognize the codons for the following types of amino acids
A. Leucine
B. Methionine
C. Serine
FIGURE 13.12 Wobble position and base-pairing rules. (a) The wobble position occurs at the third base in the mRNA codon and the corresponding base in the anticodon. (b) The revised wobble rules are slightly different from those originally proposed by Crick. The standard bases found in RNA are G, C, A, and U. In addition, the structures of bases in tRNAs may be modified. Some modified bases that may occur in the wobble position in tRNA are I = inosine; xm 5 s 2 U = 5-methyl-2-thiouridine; xm 5 Um = 5-methyl-2 - O -methyluridine; Um = 2 - O -methyluridine; xm 5 U = 5-methyluridine; xo 5 U = 5-hydroxyuridine; k 2 C = lysidine (a cytosine derivative).