- Original DNA Sequence: T A C A C C T T G G C G A C G A C T
- mRNA Sequence: A U G U G G A A C C G C U G C U G A
- Amino Acid Sequence: Met - Trp - Asn - Arg - Cys - Stop
- Mutated DNA sequence #2: T A C G A C C T T G G C G A C G A C T
- What is the mRNA sequence? A U G C U G G A A C C G C U G C U G A
- What is the amino acid sequence? Met - Leu - Glu - Pro - Leu - Leu
- Will the protein be affected? Y or N: Y
- What kind of mutation is this? Frameshift (insertion)
- How did the mutation change the resulting protein? Added a G after the first codon, shifting the reading frame and changing all subsequent amino acids; stop codon is lost, leading to a longer, nonfunctional protein.
- Mutated DNA sequence #3: T A C A C C T T A G C G A C G A C T
- What is the mRNA sequence? A U G U G G A A U C G C U G C U G A
- What is the amino acid sequence? Met - Trp - Asn - Arg - Cys - Stop
- Will the protein be affected? Y or N: N
- What kind of mutation is this? Silent
- How did the mutation change the resulting protein? The third base in the second codon changed from C to A (DNA), but the codon still codes for the same amino acid (Trp).
- Mutated DNA sequence #4: T A C A C C T T G G C G T C G A C T
- What is the mRNA sequence? A U G U G G A A C C G C A G C U G A
- What is the amino acid sequence? Met - Trp - Asn - Arg - Ser - Stop
- Will the protein be affected? Y or N: Y
- What kind of mutation is this? Missense
- How did the mutation change the resulting protein? The 10th base changed from A to T (DNA), altering the fourth codon from CGC to CGA (mRNA), which still codes for Arg — no change. Wait, correction: the 13th base changed from A to T (DNA), so mRNA changes from UGC to UGA — that’s a stop codon. So it's a nonsense mutation.
- Correction: Mutated DNA sequence #4: T A C A C C T T G G C G T C G A C T → mRNA: A U G U G G A A C C G C A G C U G A → Amino acids: Met - Trp - Asn - Arg - Ser - Stop. The 12th DNA base changed from A to T, so mRNA codon 4 changes from CGC (Arg) to CGA (Arg) — silent? No, wait, looking again: original DNA has GCG at positions 8-10, mutated has GCG unchanged. The change is at position 13: original is A, mutated is T. So DNA: ...GCG ACG... becomes ...GCG TCG... → mRNA: ...CGC UGC... becomes ...CGC AGC... → amino acid: Cys becomes Ser. So it’s a missense mutation.
- Final corrected answer for #4:
- mRNA Sequence: A U G U G G A A C C G C A G C U G A
- Amino Acid Sequence: Met - Trp - Asn - Arg - Ser - Stop
- Will the protein be affected? Y
- What kind of mutation is this? Missense
- How did the mutation change the resulting protein? Changed the fifth amino acid from Cysteine to Serine, potentially altering protein structure/function.
Parent Tip: Review the logic above to help your child master the concept of mutations practice worksheet.
