Question

use the codon chart to answer the question.

a fruit fly has this codon sequence in one of its chromosomes: aac gac cag. if the second codon undergoes a substitution mutation in which the cytosine is replaced will be the resulting peptide sequence?

threonine - leucine - phenylalanine

asparagine - aspartic acid - glutamine

leucine - leucine - valine

asparagine - glutamic acid - glutamine

Explanation:

Step1: Analyze the original codon sequence

The original codon sequence is AAC GAC CAG.

• For AAC: Looking at the mRNA codon chart, AAC codes for asparagine.
• For GAC: GAC codes for aspartic acid.
• For CAG: CAG codes for glutamine.

Step2: Analyze the mutated codon (second codon GAC → GAG)

When the second codon GAC (where C is replaced, assume substitution to G, making it GAG).

• For GAG: Looking at the mRNA codon chart, GAG codes for glutamic acid.

Answer:

asparagine - glutamic acid - glutamine