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OperonBiology
Prediction gridDifficulty 3/5 · ChallengingOlympiadConcept explanationArgumentation

Five mutations, one reading frame

Topic: Mutations

The table shows the first ten codons of the mRNA for a 250-amino-acid enzyme. Other codons you may need: GCG = Ala, GAA = Glu, ACA = Thr, GUU = Val, AGG = Arg, CAC = His, and UAA, UAG and UGA = stop. Five mutant strains each carry one change in this region of the gene, shown below as changes to the mRNA.

Data

Normal mRNA, codons 1–10 (read 5′→3′)
Codon numberCodonAmino acid
1AUGMet
2GCAAla
3UGGTrp
4AAALys
5CAGGln
6UUALeu
7GGCGly
8ACUThr
9GAUAsp
10CCAPro

For each mutation, predict the amino acid made from the first affected codon, the amino acids after it, and the length of the protein, compared with normal.

  1. Codon 2: GCA → GCG

    Amino acid from the first affected codon
    Amino acids after that codon
    Protein length

  2. Codon 4: AAA → GAA

    Amino acid from the first affected codon
    Amino acids after that codon
    Protein length

  3. Codon 5: CAG → UAG

    Amino acid from the first affected codon
    Amino acids after that codon
    Protein length

  4. One extra A inserted between codons 2 and 3

    Amino acid from the first affected codon
    Amino acids after that codon
    Protein length

  5. Codon 6 (UUA) deleted entirely

    Amino acid from the first affected codon
    Amino acids after that codon
    Protein length

Answer every part to submit.