Question

When the amino acid sequences of insulin isolated from different organisms were determined, differences were noted. For example, alanine was substituted for threonine, serine for glycine, and valine for isoleucine at corresponding positions in the protein. List the single-base changes that could occur in codons of the genetic code to produce these amino acid changes.

Short answer

Answer: 1. Alanine (A) for Threonine (T): - GCU to ACU - GCC to ACC - GCA to ACA - GCG to ACG 2. Serine (S) for Glycine (G): - GGU to AGU - GGC to AGC - GGA to UCA - GGG to UCG 3. Valine (V) for Isoleucine (I): - GUU to AUU - GUC to AUC - GUA to AUA

Step-by-step solution

Find the codons for the given amino acids

To determine the possible single-base changes, we first need to identify the codons for the amino acids mentioned in the problem. The codons for the amino acids are as follows: Alanine (Ala, A): GCU, GCC, GCA, GCG Threonine (Thr, T): ACU, ACC, ACA, ACG Serine (Ser, S): UCU, UCC, UCA, UCG, AGU, AGC Glycine (Gly, G): GGU, GGC, GGA, GGG Valine (Val, V): GUU, GUC, GUA, GUG Isoleucine (Ile, I): AUU, AUC, AUA

Identify possible single-base changes for each amino acid substitution

Now let's look at each amino acid substitution and find the possible single-base changes that could produce the given substitution: 1. Alanine (A) for Threonine (T): Possible single-base changes: GCU to ACU, GCC to ACC, GCA to ACA, GCG to ACG 2. Serine (S) for Glycine (G): Possible single-base changes: GGU to AGU, GGC to AGC, GGA to UCA, GGG to UCG 3. Valine (V) for Isoleucine (I): Possible single-base changes: GUU to AUU, GUC to AUC, GUA to AUA

Organize the results

Finally, let's list down the single-base changes that would result in the given amino acid substitutions: 1. Alanine (A) for Threonine (T): - GCU to ACU - GCC to ACC - GCA to ACA - GCG to ACG 2. Serine (S) for Glycine (G): - GGU to AGU - GGC to AGC - GGA to UCA - GGG to UCG 3. Valine (V) for Isoleucine (I): - GUU to AUU - GUC to AUC - GUA to AUA These are the single-base changes in codons that could produce the given amino acid substitutions in the insulin protein.