In a given RNA segment-AUG ACC UGG ACC CCA UCA if the first base gets mutated, the effect of this on coding by this RNA segment will result in

Options

A. a change of the first amino acid only
B. a complete change in the types as well as the sequence of almost all amino acids
C. no change in sequence of any amino acid
D. one amino acid will be less in the protein chain

Answer

To solve the question regarding the effect of a mutation in the first base of the RNA segment "AUG ACC UGG ACC CCA UCA", we will follow these steps:

### Step 1: Identify the Codons
The given RNA sequence consists of several codons. A codon is a sequence of three nucleotides that corresponds to a specific amino acid. The codons in the given sequence are:
- AUG
- ACC
- UGG
- ACC
- CCA
- UCA

### Step 2: Determine the Amino Acids
Each codon codes for a specific amino acid. Using a standard codon chart, we can identify the amino acids coded by each codon:
- AUG: Methionine (Start codon)
- ACC: Threonine
- UGG: Tryptophan
- ACC: Threonine
- CCA: Proline
- UCA: Serine

### Step 3: Analyze the Mutation
The question states that the first base of the first codon (AUG) is mutated. This means that the "A" in AUG could be replaced by another nucleotide (G, C, or U).

### Step 4: Determine the Effect of the Mutation
- If "A" is mutated to "G", the first codon becomes "GUG", which codes for Valine.
- If "A" is mutated to "C", the first codon becomes "CUG", which codes for Leucine.
- If "A" is mutated to "U", the first codon becomes "UUG", which also codes for Leucine.

In all these cases, the first amino acid (originally Methionine) will change to either Valine or Leucine, depending on the mutation. The subsequent codons (ACC, UGG, ACC, CCA, UCA) remain unchanged and will continue to code for Threonine, Tryptophan, Threonine, Proline, and Serine respectively.

### Step 5: Conclusion
The mutation affects only the first codon, leading to a change in the first amino acid while the rest of the amino acid sequence remains the same. Therefore, the correct answer to the question is that there will be a change of the first amino acid only.

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