DNA Mutations worksheet for identifying mutation types and labeling frameshift mutations.

Let’s go through each mutation one by one. We’ll compare the original DNA strand with the mutated one, figure out what changed, and then match it to the correct mutation type from the table.

We also need to remember:
→ A frameshift mutation happens when bases are inserted or deleted (not in multiples of 3), which shifts how the code is read. So we’ll put a star (*) next to those.

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1. Original: TAC GCG AAT TCA AAG
Mutated: TAC GGG AAT TCA AAG

Compare: Only the second triplet changed — GCG → GGG. That’s just one base change: C → G.
This is a point mutation: substitution.
No frameshift — still same number of bases, grouped same way.
✔ Answer: Point mutation: substitution

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2. Original: AGG TTG GGC AAA TTT
Mutated: AGG TTG GGC TTT

Compare: The “AAA” is gone. One whole triplet missing.
That’s a deletion of 3 bases — so it’s a chromosome mutation: deletion? Wait — but look at the options: there’s also “Point mutation: deletion”. But point mutations usually affect single bases. Deleting an entire codon (3 bases) is more like a small chromosome-level deletion? Actually, in many curricula, deleting even one codon is considered a “deletion mutation”, and if it’s not shifting the reading frame (since 3 bases = 1 codon), it’s NOT a frameshift.

But wait — let’s check the length:
Original: 5 triplets = 15 bases
Mutated: 4 triplets = 12 bases → missing 3 bases → no frameshift (because 3 is divisible by 3).
So this is a deletion, but since it’s removing a whole codon, it’s often called a “chromosome mutation: deletion” OR sometimes just “deletion mutation”. Looking at the table, they have both “Chromosome mutation: deletion” and “Point mutation: deletion”. Since this removes 3 bases (a full codon), it’s likely intended as Chromosome mutation: deletion. And NO star — because no frameshift.

Wait — actually, in some contexts, any deletion that isn’t 3n bases causes frameshift. Here, 3 bases deleted → no frameshift. So not starred.

✔ Answer: Chromosome mutation: deletion

*(Note: Some might argue this is a “point mutation: deletion” if they consider small deletions as point mutations — but given the table separates them, and this deletes a whole codon, “chromosome mutation: deletion” fits better.)*

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3. Original: TTC AAG GGT TAT CGC
Mutated: TTC GAA GGT TAT CGC

Compare: Second triplet: AAG → GAA. That’s two bases swapped? Let’s see:

AAG → GAA
Position 1: A → G
Position 2: A → A (same)
Position 3: G → A
Actually, it’s not a simple swap — it’s a rearrangement within the codon? Or maybe inversion?

Wait — look: AAG becomes GAA. If you reverse AAG, you get GAA! Yes! So the order of bases in that codon is reversed. That’s an inversion — specifically, a small inversion within a codon.

Is this a chromosome mutation? Inversions can be large-scale, but here it’s tiny. However, looking at the table, “Chromosome mutation: inversion” is listed. There’s no “point mutation: inversion”. So probably they want us to call this Chromosome mutation: inversion.

And does it cause frameshift? No — still 3 bases, just reordered. Reading frame unchanged.

✔ Answer: Chromosome mutation: inversion

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4. Original: TAC GCG CCC TTT AAA
Mutated: TCG CGC CCT TTA AA

Wait — let’s write them aligned:

Original: TAC GCG CCC TTT AAA
Mutated: TCG CGC CCT TTA AA ← only 14 bases? Let’s count:

Original: 5 triplets = 15 bases
Mutated: TCG CGC CCT TTA AA → that’s 4 full triplets + “AA” = 14 bases? That doesn’t make sense. Maybe typo? Let me re-read:

User wrote:
Mutated DNA strand: TCG CGC CCT TTA AA

But that’s 14 characters? Should be 15? Perhaps it’s meant to be “TTA AA” as “TTA AA” — but that’s still 5 letters? Wait — maybe it’s “TTA AA” meaning “TTA” and then “AA” — but that breaks the triplet.

Actually, looking closely:
Original: TAC GCG CCC TTT AAA → positions:
1-3: TAC
4-6: GCG
7-9: CCC
10-12: TTT
13-15: AAA

Mutated: TCG CGC CCT TTA AA →
If we break it:
TCG (1-3)
CGC (4-6)
CCT (7-9)
TTA (10-12)
AA? (13-14) — missing one base? That would be a deletion of one base → frameshift!

But wait — perhaps it’s a typo and it’s supposed to be “TTA AA” as “TTA” and “AA” — but that’s incomplete. Alternatively, maybe it’s “TTA AA” meaning the last part is “TTA” and then “AA” — but that’s 5 bases for last two codons? Confusing.

Another possibility: maybe the mutated strand is “TCG CGC CCT TTA AA” — but if we assume it’s 15 bases, perhaps it’s “TCG CGC CCT TTA AA” with space error — maybe it’s “TCG CGC CCT TTA AA” → but “AA” should be “AAA”? No.

Wait — let’s count letters without spaces:

Original: TACGCGCCCTTTAAA → 15 letters
Mutated: TCGCGCCCTTAAA → 13 letters? That can’t be.

Perhaps it’s “TCG CGC CCT TTA AA” — if we remove spaces: TCGCGCCCTTAAA → 13 characters? Still wrong.

I think there might be a typo in the problem. But let’s look at the pattern:

Original: TAC GCG CCC TTT AAA
Mutated: TCG CGC CCT TTA AA

Notice:
First codon: TAC → TCG (changed)
Second: GCG → CGC (reversed?)
Third: CCC → CCT (last base C→T)
Fourth: TTT → TTA (last base T→A)
Fifth: AAA → AA (missing one A)

Ah! So the last codon lost one base. That means total bases: 14 instead of 15. So deletion of one base → frameshift!

Also, multiple changes — but the key is the deletion of one base at the end.

But also, other changes: first codon changed, second reversed, etc. This looks messy.

Alternatively, perhaps it’s a combination, but the question asks for “the correct name” — implying one primary mutation.

Looking at the changes:

- TAC → TCG: substitution?
- GCG → CGC: inversion?
- CCC → CCT: substitution
- TTT → TTA: substitution
- AAA → AA: deletion of one base

The most significant is the deletion of one base, which causes frameshift. Also, the other changes might be red herrings or part of a larger event.

But notice: if you delete one base from the end, the whole sequence after that shifts — but here, the changes are throughout.

Another idea: perhaps it’s a translocation? But translocation involves moving a segment to another chromosome — not indicated here.

Wait — let’s align them properly:

Original: T A C G C G C C C T T T A A A
Mutated: T C G C G C C C T T T A A ?

If mutated is “TCG CGC CCT TTA AA”, and we assume it’s 14 bases, then compared to original 15, it’s missing one base. Where? At the end: AAA → AA, so deletion of last A.

But then why are earlier bases changed? For example, position 2: A→C, position 4: G→C, etc.

This suggests multiple point mutations plus a deletion. But the question likely expects one answer.

Perhaps it’s a frameshift due to deletion, and the other changes are errors in transcription? Unlikely.

Another thought: maybe the mutated strand is miswritten. Let me check online or standard problems — but I can't.

Perhaps "TCG CGC CCT TTA AA" is meant to be "TCG CGC CCT TTA AA" with "AA" being a mistake for "AAA", but then it's 15 bases: TCG CGC CCT TTA AAA — but user wrote "TTA AA", not "TTA AAA".

User wrote: "Mutated DNA strand: TCG CGC CCT TTA AA"

Let’s count the letters in "TCG CGC CCT TTA AA":
TCG=3, CGC=3, CCT=3, TTA=3, AA=2 → total 14 bases.

Original is 15 bases. So deletion of 1 base.

Where is the deletion? If we assume the first four codons are similar but not identical, and the last is shortened.

But comparing:

Pos 1-3: TAC vs TCG — different
4-6: GCG vs CGC — different
7-9: CCC vs CCT — different
10-12: TTT vs TTA — different
13-15: AAA vs AA — missing one

So every codon is altered, and one base missing. This is complicated.

Perhaps it's a series of substitutions and a deletion, but the deletion causes frameshift.

In many textbooks, if there's a deletion of one base, it's a frameshift mutation, regardless of other changes.

Also, looking at the options, "Point mutation: deletion" is there, and it would cause frameshift.

Moreover, the other changes might be to distract, but the key is the net effect: loss of one base → frameshift.

So I'll go with Point mutation: deletion and add a star (*) because it causes frameshift.

But is it "point mutation" or "chromosome mutation"? Point mutation typically refers to single base changes, including deletions of one base.

Yes, "point mutation: deletion" usually means deletion of one or few bases, causing frameshift if not multiple of 3.

Here, deletion of 1 base → frameshift.

So ✔ Answer: Point mutation: deletion *

*(Star for frameshift)*

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5. Original: CCT TGT GGA AAC CGC
Mutated: CCT TGT TGT GGA AAC CGC

Compare: Mutated has an extra "TGT" inserted after the second codon.

Original: 5 triplets
Mutated: 6 triplets → insertion of one codon (3 bases).

Insertion of 3 bases → no frameshift (since 3 is divisible by 3).

What type? Insertion of a segment. Could be "chromosome mutation: duplication" if it's copying a part, or "insertion".

Looking at the table: "Chromosome mutation: duplication" and "Point mutation: insertion".

Here, "TGT" is duplicated — it was already there as the second codon, and now it's repeated.

Original: CCT TGT GGA AAC CGC
Mutated: CCT TGT TGT GGA AAC CGC → so "TGT" is duplicated.

So this is a duplication — specifically, tandem duplication of a codon.

Thus, Chromosome mutation: duplication

No frameshift.

✔ Answer: Chromosome mutation: duplication

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6. Original: TAG CAT TAC ACT GAC
Mutated: TAG CAT TAC ACT GAC TTT

Compare: Mutated has an extra "TTT" at the end.

Insertion of 3 bases → no frameshift.

Type: insertion of a codon. Not a duplication (since TTT wasn't there before), so it's an insertion.

Table has "Point mutation: insertion" — which typically means insertion of one or few bases.

Since it's 3 bases, and not causing frameshift, it could be "point mutation: insertion".

Is there "chromosome mutation: insertion"? No, only "translocation", "duplication", etc.

So likely Point mutation: insertion

No star.

✔ Answer: Point mutation: insertion

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7. Original: AAA GTA CCT TAC CAT
Mutated: AAA GCT ACC TTA CCA T

Let’s align:

Original: AAA GTA CCT TAC CAT → 5 triplets = 15 bases
Mutated: AAA GCT ACC TTA CCA T → let's count: AAA(3) GCT(3) ACC(3) TTA(3) CCA(3) T(1) → 16 bases? That can't be.

User wrote: "AAA GCT ACC TTA CCA T" — so last is "T", making it 16 characters? But original is 15.

Perhaps it's "CCA T" meaning "CCA" and "T" — but that's 4 bases for last two? Messy.

Without spaces: Original: AAAGTACCTTACCAT → 15 letters
Mutated: AAAGCTACCTTACC AT → if "CCA T" is "CCAT", then AAAGCTACCTTACCAT → 16 letters? Still off.

Assume mutated is "AAA GCT ACC TTA CCA T" — if we take it as 16 bases, then insertion of one base? But where?

Compare base by base:

Original: A A A G T A C C T T A C C A T
Mutated: A A A G C T A C C T T A C C A T ?

If mutated is longer, say 16 bases, then perhaps an insertion.

But let's see the sequence:

After "AAA", original has "GTA", mutated has "GCT" — so G same, T→C, A→T? Then "CCT" vs "ACC" — completely different.

This looks like multiple substitutions and possibly an insertion.

Notice: mutated has "GCT ACC TTA CCA T" — while original has "GTA CCT TAC CAT"

If we shift: perhaps a frameshift occurred.

Count bases:

Original: 15 bases
Mutated: "AAA GCT ACC TTA CCA T" — if we remove spaces: AAAGCTACCTTACCAT — that's 16 characters? A-A-A-G-C-T-A-C-C-T-T-A-C-C-A-T → 16 bases.

So insertion of one base? Where? Between position 4 and 5? Original pos 4 is G, pos 5 is T; mutated pos 4 is G, pos 5 is C — so after G, a C is inserted? Then the rest shifts.

Let's simulate:

Original: 1:A,2:A,3:A,4:G,5:T,6:A,7:C,8:C,9:T,10:T,11:A,12:C,13:C,14:A,15:T

Mutated: 1:A,2:A,3:A,4:G,5:C,6:T,7:A,8:C,9:C,10:T,11:T,12:A,13:C,14:C,15:A,16:T

So compared to original, after position 4 (G), instead of T, we have C, then T, then A, etc. It's as if a 'C' is inserted after position 4, and then the sequence continues but shifted.

Specifically, original from pos 5: T A C C T T A C C A T
Mutated from pos 5: C T A C C T T A C C A T

So it's like the 'C' is inserted, and then the original sequence starts from pos 5 but with a shift.

Actually, mutated pos 5-16: C T A C C T T A C C A T
Original pos 5-15: T A C C T T A C C A T

So mutated has an extra 'C' at the beginning of this substring, and then matches original from pos 5 onwards, but since it's shifted, the grouping changes.

This is a classic frameshift caused by insertion of one base.

The mutation is an insertion of one base (C) after the fourth base.

So it's a point mutation: insertion and it causes frameshift → add star.

Even though other bases seem changed, it's because of the shift in reading frame.

For example, original codon 2: GTA → after insertion, it becomes GCT (because G + inserted C + next T = GCT), then next is ACC (original A C C, but now shifted), etc.

Yes, so the apparent changes are due to the frameshift from inserting one base.

So ✔ Answer: Point mutation: insertion *

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Now, summarizing all answers:

1. Point mutation: substitution
2. Chromosome mutation: deletion
3. Chromosome mutation: inversion
4. Point mutation: deletion *
5. Chromosome mutation: duplication
6. Point mutation: insertion
7. Point mutation: insertion *

For #4 and #7, we added stars because they cause frameshift mutations.

Final Answer:

1. Point mutation: substitution
2. Chromosome mutation: deletion
3. Chromosome mutation: inversion
4. Point mutation: deletion *
5. Chromosome mutation: duplication
6. Point mutation: insertion
7. Point mutation: insertion *