Question

Sequence the following events involved in a point mutation in DNA.
A. Alteration in the amino acid sequence of a protein.
B. Change in mRNA codon during transcription.
C. Substitution of a single nucleotide in the DNA sequence.
D. Possible disruption of protein function or structure.
Choose the correct answer from the options given below:

• A. A, B, C, D
• B. B, A, C, D
• C. A, C, B, D
• D. C, B, A, D

Hint:

Always follow the central dogma: DNA \(\rightarrow\) RNA \(\rightarrow\) Protein. The problem must start at the DNA level (mutation), then affect the RNA (transcription), then the protein sequence (translation), and finally the protein's function (phenotype).

Answer 1

The Correct Option is D

Step 1: Concept Overview:
The question requires arranging events in chronological order following a DNA point mutation, based on the central dogma (DNA \(\rightarrow\) RNA \(\rightarrow\) Protein).
Step 2: Step-by-Step Explanation:
Here's the sequence from mutation to effect:

C. Single nucleotide substitution in DNA: The process begins with the point mutation, a single DNA base change. This is the initiating event.
B. mRNA codon change during transcription: The mutated DNA is transcribed into mRNA. The DNA base change leads to a corresponding mRNA codon change.
A. Altered protein amino acid sequence: During translation, the ribosome reads mRNA codons. If the changed codon specifies a different amino acid (missense mutation), the protein's amino acid sequence is altered.
D. Potential protein dysfunction or structural change: The altered amino acid sequence can change the protein's 3D structure, potentially disrupting its biological function. This is the final consequence.
Step 3: Conclusion:
The correct sequence is: DNA mutation (C) \(\rightarrow\) mRNA codon change (B) \(\rightarrow\) Amino acid sequence change (A) \(\rightarrow\) Protein dysfunction (D), corresponding to C, B, A, D.