Question

Compare the codons with a purine, either \(\mathrm{A}\) or \(\mathrm{G}\), as the second base. Do the majority of the amino acids specified by these codons have hydrophilic or hydrophobic side chains?

Short answer

Answer: The majority side chain property of amino acids specified by codons with a purine as the second base is hydrophilic (polar).

Step-by-step solution

Identify the codons with purine as the second base

To analyze the codons with a purine (A or G) as the second base, we will need to look at the genetic code. There are four possible bases in codon positions (A, T, G, and C), so there will be 16 codons with purine as the second base: four with A and four with G in the second position.

Determine the corresponding amino acids

Next, we will use a table of genetic codes to identify the corresponding amino acids for each of the 16 codons. Here is a list of the amino acids corresponding to the codons with purine as the second base: 1. AA* (Asn/N) 2. GA* (Asp/D) 3. AC* (Thr/T) 4. GC* (Ala/A) 5. AG* (Arg/R) 6. GG* (Gly/G) 7. AT* (Ile/I) 8. GT* (Val/V) 9. AAG (Lys/K) 10. GAG (Glu/E) 11. ACT (Thr/T) 12. GCT (Ala/A) 13. AG* (Ser/S) 14. GG* (Gly/G) 15. ATT (Ile/I) 16. GTT (Val/V) '*' represents that any nucleotide can be on that position (U, C, A, G).

Classify the amino acids as hydrophilic or hydrophobic

Now we will classify each amino acid as either hydrophilic (polar) or hydrophobic (nonpolar) based on its side chain: Hydrophilic (polar): Asn, Asp, Thr, Arg, Lys, Glu, Ser Hydrophobic (nonpolar): Ala, Gly, Ile, Val

Determine which side chain property is more common

Finally, let's count the occurrence of each property to see which is more common: Hydrophilic (polar): 7 Hydrophobic (nonpolar): 4 Thus, the majority of amino acids specified by codons with a purine as the second base have hydrophilic (polar) side chains.