Question

part 3. the following mutation is found in the somatic cell of an orangutan
original dna: atg-cgg-tta
mutated: atg-cgg-ttt
after translation, what would be the correct amino acids of the original and
mutated sequence?

○ original: leu, mutated: phe
○ original: thr, mutated: lys
○ original: lys, mutated: asn
○ original: asn, mutated: lys

Explanation:

Step1: Recall Genetic Code

Each 3 - base DNA codon (after transcription to mRNA, but since DNA to mRNA is T→U, we can use DNA codons with T as U for amino acid lookup) codes for an amino acid. The genetic code table: TTA (DNA) → mRNA UUA, which codes for Leu (Leucine); TTT (DNA) → mRNA UUU, which codes for Phe (Phenylalanine). Wait, no, wait. Wait, the original DNA is ATG - CGG - TTA. Let's break into codons: ATG, CGG, TTA. Mutated: ATG, CGG, TTT. Wait, but the question is about the third codon? Wait, maybe I misread. Wait, the options are about the third codon? Wait, no, maybe the codons are read as triplets. Wait, original third codon: TTA. Mutated third codon: TTT. Let's check the genetic code:

For DNA codon (since during translation, mRNA is used, so DNA T is mRNA U). So TTA (DNA) → mRNA UUA. UUA codes for Leu (Leucine). TTT (DNA) → mRNA UUU. UUU codes for Phe (Phenylalanine). Now check the options: First option: Original Leu, Mutated: Phe. That matches. Let's verify the other options: Second option: Original Thr? Thr codon is ACU etc. No. Third option: Lys? Lys codon is AAA, AAG. No. Fourth option: Aus? Maybe a typo, but no. So the correct option is the first one: Original Leu, Mutated: Phe.

Answer:

A. Original Leu, Mutated: Phe (assuming the first option is labeled A, as per the options given with "Original Leu, Mutated: Phe" as the first choice)