Question

mutations summative activity
directions: analyze each mutation mutated dna sequence with the original
dna. write the mrna. circle the dna, rna, and amino acid that’s different.
circle the type of mutation that occurred. please use your notes. you are working
alone, but you may ask for help from the teacher if you need it! put in the
turn in basket when done.
original sequence:
dna strand t a c t t t g t g a c g t a g a t c
mrna a u g a a a c a c u g c a u c u a g
amino acids met lys his cys ile stop
mutated dna #1 t a c t t t g t g a t g t a g a t c
mrna
amino acids
type of mutation /
how it affects the
protein substitution
silent
mutation substitution
missense
mutation substitution
nonsense
mutation frameshift
insertion frameshift
deletion
mutated dna #2 t a c t t t g t g a c g a t a g a t c
mrna
amino acids
type of mutation /
how it affects the
protein substitution
silent
mutation substitution
missense
mutation substitution
nonsense
mutation frameshift
insertion frameshift
deletion

Explanation:

Step1: Analyze Mutated DNA #1

The original DNA strand has a segment \( \text{ACG} \) (position 10 - 12: A, C, G). In Mutated DNA #1, this becomes \( \text{ATG} \) (A, T, G). To find mRNA, we transcribe DNA to mRNA (A→U, T→A, C→G, G→C). So original mRNA for \( \text{ACG} \) is \( \text{UGC} \) (coding for Cys), and mutated mRNA for \( \text{ATG} \) is \( \text{UAC} \) (coding for Tyr? Wait, no, let's re - check the DNA to mRNA transcription. DNA base: A→mRNA U, T→A, C→G, G→C. So original DNA: TAC TTT GTG ACG TAG ATC. Mutated DNA #1: TAC TTT GTG ATG TAG ATC. So the DNA triplet change is ACG → ATG. Transcribing ACG: A→U, C→G, G→C → UGC (Cys). Transcribing ATG: A→U, T→A, G→C → UAC. Wait, but also, let's check the entire mRNA for Mutated DNA #1. Original DNA: T A C T T T G T G A C G T A G A T C. Mutated DNA #1: T A C T T T G T G A T G T A G A T C. So the DNA sequence from position 10 - 12 (ACG) becomes ATG. Now, transcribe the entire Mutated DNA #1 to mRNA: T→A, A→U, C→G, T→A, T→A, T→A, G→C, T→A, G→C, A→U, T→A, G→C, T→A, A→U, G→C, A→U, T→A, C→G. Wait, maybe a better way: split into triplets. Original DNA triplets: TAC, TTT, GTG, ACG, TAG, ATC. Mutated DNA #1 triplets: TAC, TTT, GTG, ATG, TAG, ATC. Now transcribe each triplet: TAC→AUG, TTT→AAA, GTG→CAC, ATG→UAC, TAG→AUC, ATC→UAG. Now, the amino acids: AUG→Met, AAA→Lys, CAC→His, UAC→Tyr, AUC→Ile, UAG→STOP? Wait, no, original amino acids: Met, Lys, His, Cys, Ile, STOP. The change is in the fourth triplet: ACG→UGC (Cys) vs ATG→UAC (Tyr). So this is a substitution (ACG to ATG is a single base change: C→T in DNA, which is a substitution mutation. Wait, but also, let's check the type of mutation. Substitution: one base is replaced. Frameshift: insertion or deletion. Here, it's a substitution (C→T in DNA, so ACG→ATG). Now, does it change the amino acid? Original: Cys, mutated: Tyr? Wait, maybe I made a mistake. Wait, DNA triplet ACG: A (adenine), C (cytosine), G (guanine). Transcribe to mRNA: U (uracil), G (guanine), C (cytosine) → UGC (codes for Cysteine). DNA triplet ATG: A, T, G → mRNA U, A, C → UAC (codes for Tyrosine). So the amino acid changes from Cys to Tyr, so it's a missense substitution (since it changes the amino acid). But also, let's check Mutated DNA #2. Original DNA: TAC TTT GTG ACG TAG ATC. Mutated DNA #2: TAC TTT GTG ACG ATG ATC? Wait, no, the Mutated DNA #2 is TAC TTT GTG ACG ATG ATC? Wait, the image shows Mutated DNA #2 as TAC TTT GTG ACG ATG ATC? Wait, no, the user's image for Mutated DNA #2: T A C T T T G T G A C G A T G A T C? Wait, maybe I misread. Alternatively, let's focus on the type of mutation for Mutated DNA #1. The DNA sequence has a single base change (C→T in the ACG triplet to make ATG), so it's a substitution. Now, for the mRNA of Mutated DNA #1: as we transcribed, AUG, AAA, CAC, UAC, AUC, UAG. Amino acids: Met, Lys, His, Tyr, Ile, STOP. The original amino acids: Met, Lys, His, Cys, Ile, STOP. So the fourth amino acid changes from Cys to Tyr, so it's a missense substitution. But also, let's check the frameshift. Wait, no, the number of bases is the same, so it's a substitution. Now, for Mutated DNA #2: let's look at the DNA sequence. Original DNA: TAC TTT GTG ACG TAG ATC. Mutated DNA #2: TAC TTT GTG ACG ATG ATC? Wait, no, the image shows Mutated DNA #2 as TAC TTT GTG ACG ATG ATC? Wait, maybe the triplet TAG (original) becomes ATG (mutated)? Wait, no, let's count the bases. Original DNA length: let's count the bases in original DNA: T(1), A(2), C(3), T(4), T(5), T(6), G(7), T(8), G(9), A(10), C(11), G(12), T(13), A(14), G(15), A(16), T(17), C(18). Mutated DNA #1: T(1), A(2), C(3), T(4), T(5), T(6), G(7), T(8), G(9), A(10), T(11), G(12), T(13), A(14), G(15), A(16), T(17), C(18). So base 11: C→T (substitution). Mutated DNA #2: T(1), A(2), C(3), T(4), T(5), T(6), G(7), T(8), G(9), A(10), C(11), G(12), A(13), T(14), G(15), A(16), T(17), C(18). Wait, base 13: T→A? No, original DNA base 13: T, mutated DNA #2 base 13: A? Wait, maybe it's an insertion or deletion? Wait, original DNA triplets: TAC (1 - 3), TTT (4 - 6), GTG (7 - 9), ACG (10 - 12), TAG (13 - 15), ATC (16 - 18). Mutated DNA #2 triplets: TAC (1 - 3), TTT (4 - 6), GTG (7 - 9), ACG (10 - 12), ATG (13 - 15), ATC (16 - 18). Wait, base 13: T→A (substitution), base 14: A→T (substitution)? No, original TAG: T(13), A(14), G(15). Mutated ATG: A(13), T(14), G(15). So two base substitutions? Or is it a frameshift? Wait, no, the number of bases is the same. Wait, maybe I'm overcomplicating. Let's go back to the problem: we need to write the mRNA for Mutated DNA #1.

Mutated DNA #1 sequence: T A C T T T G T G A T G T A G A T C.

To transcribe DNA to mRNA, we use the rule: A (DNA) → U (mRNA), T (DNA) → A (mRNA), C (DNA) → G (mRNA), G (DNA) → C (mRNA).

So let's transcribe each base:

T → A

A → U

C → G

T → A

T → A

T → A

G → C

T → A

G → C

A → U

T → A

G → C

T → A

A → U

G → C

A → U

T → A

C → G

Now, let's group into triplets (since mRNA is read in triplets for translation):

First triplet: TAC → AUG

Second triplet: TTT → AAA

Third triplet: GTG → CAC

Fourth triplet: ATG → UAC

Fifth triplet: TAG → AUC

Sixth triplet: ATC → UAG

So the mRNA sequence for Mutated DNA #1 is AUG AAA CAC UAC AUC UAG.

Now, for the amino acids:

AUG → Methionine (Met)

AAA → Lysine (Lys)

CAC → Histidine (His)

UAC → Tyrosine (Tyr)

AUC → Isoleucine (Ile)

UAG → Stop codon (STOP)

Now, let's check the type of mutation. The original DNA triplet at position 4 was ACG (transcribed to UGC, coding for Cysteine), and the mutated triplet is ATG (transcribed to UAC, coding for Tyrosine). This is a substitution mutation (since one base in the DNA triplet was changed: C → T in DNA, which changes ACG to ATG). Since the amino acid changed, it's a missense substitution. But for the mRNA, we just need to transcribe the DNA.

Step2: Write the mRNA for Mutated DNA #1

Using the transcription rules, the mRNA for Mutated DNA #1 (TAC TTT GTG ATG TAG ATC) is AUG AAA CAC UAC AUC UAG.

Answer:

The mRNA for Mutated DNA #1 is \(\boldsymbol{\text{AUG AAA CAC UAC AUC UAG}}\)