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: Understanding the Concept:
The question asks for the correct chronological order of events that occur as a consequence of a point mutation in the DNA, following the principles of the central dogma of molecular biology (DNA \(\rightarrow\) RNA \(\rightarrow\) Protein).
Step 2: Detailed Explanation:
Let's trace the flow of information from the initial mutation to its final effect:

C. Substitution of a single nucleotide in the DNA sequence: The process must start with the mutation itself. A point mutation is a change in a single nucleotide base in the DNA. This is the root cause.
B. Change in mRNA codon during transcription: During transcription, the mutated DNA sequence serves as a template to create an mRNA molecule. The change in the DNA base will result in a corresponding change in the mRNA codon.
A. Alteration in the amino acid sequence of a protein: During translation, the ribosome reads the mRNA codons. If the changed codon now specifies a different amino acid (a missense mutation), the resulting polypeptide chain will have an altered amino acid sequence.
D. Possible disruption of protein function or structure: The change in the amino acid sequence can alter the protein's three-dimensional structure, which in turn can disrupt or change its biological function. This is the final phenotypic consequence of the mutation.
Step 3: Final Answer:
The correct sequence of events is: DNA mutation (C) \(\rightarrow\) mRNA codon change (B) \(\rightarrow\) Amino acid sequence change (A) \(\rightarrow\) Protein function disruption (D). This corresponds to the order C, B, A, D.