Question

original dna sequence: tacaccttggcgacgact
mutated dna sequence #2: tacgaccttggcgacgact
mrna mutated sequence #2: _________________________

• circle the change that occurred in the mutated sequence.

(note: it makes it easier to mark the codons on the mrna with brackets)
mutated amino acid sequence: _________________________
mutation type: _________________________

of different amino acids (compared to original amino acid sequence): ________

original dna sequence: tacaccttggcgacgact
mutated dna sequence #3: tacaccttagcgacgact
mrna mutated sequence #3: _________________________

• circle the change that occurred in the mutated sequence.

(note: it makes it easier to mark the codons on the mrna with brackets)
mutated amino acid sequence: _________________________
mutation type: _________________________

of different amino acids (compared to original amino acid sequence): ________

original dna sequence: tacaccttggcgacgact
mutated dna sequence #4: tacacctttgcgacgact
mrna mutated sequence #4: _________________________

• circle the change that occurred in the mutated sequence.

(note: it makes it easier to mark the codons on the mrna with brackets)
mutated amino acid sequence: _________________________
mutation type: _________________________

of different amino acids (compared to original amino acid sequence): ________

Answer:

Mutated DNA Sequence #2

Step 1: Transcribe DNA to mRNA (mutated)

Original DNA: TACACCTTGGCGACGACT
Mutated DNA #2: TACGACCTTGGCGACGACT (insertion of G at position 4)
mRNA is transcribed as A pairs with U, T with A, C with G, G with C.
So mutated DNA to mRNA: AUGCUGGAAGCCUGCUGA (note: the inserted G in DNA becomes C in mRNA, and we adjust the reading frame? Wait, no—wait, the original DNA sequence: let's count the bases. Original DNA: T A C A C C T T G G C G A C G A C T (18 bases). Mutated #2: T A C G A C C T T G G C G A C G A C T (19 bases? Wait, original: positions 1 - 18: T(1),A(2),C(3),A(4),C(5),C(6),T(7),T(8),G(9),G(10),C(11),G(12),A(13),C(14),G(15),A(16),C(17),T(18). Mutated #2: T(1),A(2),C(3),G(4),A(5),C(6),C(7),T(8),T(9),G(10),G(11),C(12),G(13),A(14),C(15),G(16),A(17),C(18),T(19)? Wait, maybe I miscounted. Alternatively, the original DNA is TACACCTTGGCGACGACT (let's split into codons: TAC ACC TTG GCG ACG ACT). Mutated #2: TAC GAC CTT GGC GAC GACT (so insertion of G after TAC: TAC GAC CTT GGC GAC GACT—so the mRNA would be AUG CUG GAA GCC UGC UGA (wait, no: DNA to mRNA is T→A, A→U, C→G, G→C. So TAC → AUG, GAC → CUG, CTT → GAA, GGC → CCG? Wait, no, original DNA codons: TAC (codon 1), ACC (2), TTG (3), GCG (4), ACG (5), ACT (6). Mutated #2: TAC (1), GAC (2), CTT (3), GGC (4), GAC (5), GACT (6? No, extra T? Maybe a typo, but assuming insertion of G at position 4 (original A at position 4, now G). So mRNA mutated #2: AUG CUG GAA CCG UGC UGA (wait, no, let's do base - by - base:

Original DNA: T A C A C C T T G G C G A C G A C T
Mutated #2: T A C G A C C T T G G C G A C G A C T

Transcribe each base:
T→A, A→U, C→G, G→C, A→U, C→G, C→G, T→A, T→A, G→C, G→C, C→G, G→C, C→G, G→C, A→U, C→G, G→C, A→U, C→G, T→A? Wait, no, the mutated DNA has one extra base (insertion). So the mRNA sequence will be: AUG CUG GAA GCC UGC UGA (wait, maybe I made a mistake. Let's use the correct transcription: DNA to mRNA is complementary, with T→A, A→U, C→G, G→C.

So mutated DNA #2: T A C G A C C T T G G C G A C G A C T
mRNA: A U G C U G G A A G C C U G C U G A

Step 2: Determine amino acid sequence (mutated)

Use codon table:
AUG→Met, CUG→Leu, GAA→Glu, GCC→Ala, UGC→Cys, UGA→Stop.

Original amino acid sequence (from original DNA: TAC→AUG(Met), ACC→UGG(Trp), TTG→AAC(Asn)? Wait, no, original DNA: TAC (mRNA AUG→Met), ACC (UGG→Trp), TTG (AAC→Asn), GCG (CGC→Arg), ACG (UGC→Cys), ACT (UGA→Stop). Wait, no, codon table: ACC (DNA) → UGG (mRNA) → Trp; TTG (DNA) → AAC (mRNA) → Asn; GCG (DNA) → CGC (mRNA) → Arg; ACG (DNA) → UGC (mRNA) → Cys; ACT (DNA) → UGA (mRNA) → Stop.

Mutated amino acid sequence: AUG(Met), CUG(Leu), GAA(Glu), GCC(Ala), UGC(Cys), UGA(Stop).

Step 3: Mutation type

Insertion (added a G, so frameshift mutation).

Step 4: Number of different amino acids

Original amino acids: Met, Trp, Asn, Arg, Cys, Stop.
Mutated: Met, Leu, Glu, Ala, Cys, Stop.
Different amino acids: Trp→Leu, Asn→Glu, Arg→Ala. So 3 different.

Mutated DNA Sequence #3

Step 1: Transcribe DNA to mRNA (mutated)

Original DNA: TACACCTTGGCGACGACT
Mutated #3: TACACCTTAGCGACGACT (substitution: G→A at position 9? Wait, original DNA: T A C A C C T T G G C G A C G A C T
Mutated #3: T A C A C C T T A G C G A C G A C T

Transcribe each base:
T→A, A→U, C→G, A→U, C→G, C→G, T→A, T→A, A→U, G→C, C→G, G→C, A→U, C→G, G→C, A→U, C→G, T→A

So mRNA mutated #3: A U G U G G A A U C G C U G C U G A

Step 2: Determine amino acid sequence (mutated)

Codon table:
AUG→Met, UGG→Trp, AAU→Asn, CGC→Arg, UGC→Cys, UGA→Stop.

Original amino acid sequence: Met, Trp, Asn, Arg, Cys, Stop.

Step 3: Mutation type

Substitution (G→A at DNA level, which is a point mutation, missense? Wait, original DNA codon TTG (→AAC→Asn), mutated to TTA (→AAU→Asn). Wait, no: original DNA codon at position 7 - 9: TTG (DNA) → AAC (mRNA) → Asn. Mutated DNA codon: TTA (DNA) → AAU (mRNA) → Asn. Wait, that's a silent mutation? Wait, no, original DNA: T T G (codon 3), mutated to T T A (codon 3). So TTG→AAC (Asn), TTA→AAU (Asn). So it's a silent mutation? Wait, maybe I made a mistake. Wait, original DNA: TAC ACC TTG GCG ACG ACT (codons: 1 - 6). Mutated #3: TAC ACC TTA GCG ACG ACT (codon 3: TTA instead of TTG). So mRNA codon 3: AAU instead of AAC, both code for Asn. So amino acid sequence: Met, Trp, Asn, Arg, Cys, Stop (same as original? Wait, no, GCG (codon 4) in original: GCG→CGC→Arg. Mutated DNA codon 4: GCG (wait, no, mutated DNA is TACACCTTAGCGACGACT, so codon 4: GCG? Wait, no, codons are 3 bases: TAC (1), ACC (2), TTA (3), GCG (4), ACG (5), ACT (6). So mRNA codon 4: CGC→Arg (same as original). So amino acid sequence is same as original? Wait, no, maybe the mutation is at a different position. Wait, original DNA: T A C A C C T T G G C G A C G A C T (bases 1 - 18). Mutated #3: T A C A C C T T A G C G A C G A C T (base 9: G→A). So codon 3: TTG (bases 7 - 9) → TTA (bases 7 - 9). So mRNA codon 3: AAC→AAU, both Asn. So amino acid sequence: Met, Trp, Asn, Arg, Cys, Stop (same as original).

Step 3: Mutation type

Substitution (point mutation), silent mutation (no change in amino acid).

Step 4: Number of different amino acids

0.

Mutated DNA Sequence #4

Step 1: Transcribe DNA to mRNA (mutated)

Original DNA: TACACCTTGGCGACGACT
Mutated #4: TACACCTTTGCGACGACT (substitution: G→T at position 9? Wait, original DNA: T A C A C C T T G G C G A C G A C T
Mutated #4: T A C A C C T T T G C G A C G A C T

Transcribe each base:
T→A, A→U, C→G, A→U, C→G, C→G, T→A, T→A, T→A, G→C, C→G, G→C, C→G, G→C, C→G, A→U, C→G, G→C, T→A

So mRNA mutated #4: A U G U G G A A A C G C U G C U G A

Step 2: Determine amino acid sequence (mutated)

Codon table:
AUG→Met, UGG→Trp, AAA→Lys, CGC→Arg, UGC→Cys, UGA→Stop.

Original amino acid sequence: Met, Trp, Asn, Arg, Cys, Stop.

Step 3: Mutation type

Substitution (point mutation), missense (TTG→TTA was silent, but here TTG→TTT: TTG→AAC→Asn, TTT→AAA→Lys). So missense mutation.

Step 4: Number of different amino acids

1 (Asn→Lys).

Final Answers (for each mutated sequence)

Mutated Sequence #2

• mRNA mutated sequence #2: $\boldsymbol{AUGCUGGAAGCCUGCUGA}$
• Mutated Amino Acid Sequence: Met, Leu, Glu, Ala, Cys, Stop
• Mutation type: Insertion (frameshift)
• # of different amino acids: $\boldsymbol{3}$

Mutated Sequence #3

• mRNA mutated sequence #3: $\boldsymbol{AUGUGGAAUCGCUGCUGA}$
• Mutated Amino Acid Sequence: Met, Trp, Asn, Arg, Cys, Stop
• Mutation type: Substitution (silent)
• # of different amino acids: $\boldsymbol{0}$

Mutated Sequence #4

• mRNA mutated sequence #4: $\boldsymbol{AUGUGGAAACGCUGCUGA}$
• Mutated Amino Acid Sequence: Met, Trp, Lys, Arg, Cys, Stop
• Mutation type: Substitution (missense)
• # of different amino acids: $\boldsymbol{1}$

(Note: The circling of the change in the mutated sequence should be done on the DNA sequence: for #2, circle the inserted G; for #3, circle the A that replaced G; for #4, circle the T that replaced G.)