Correct option is A
Explanation-
Statement A - In vitro transcription of the cloned cDNA for this gene in a cell-free system to produce the corresponding mRNA - CORRECT
This is a standard method to obtain mRNA for a specific gene, which is then injected into oocytes to express the protein (channel).
Statement B - Injecting above mentioned mRNA into frog oocytes - CORRECT
Xenopus oocytes are often used as a heterologous expression system. After injection, they express the protein (K⁺ channel), which can then be studied functionally.
Statement C - Measuring channel-protein activity using a patch-clamping technique - CORRECT
Patch-clamp is a gold-standard technique to record ionic currents and assess ion channel function in real time.
Statement D - Knocking out the gene encoding the homolog of this channel in frog oocytes and measuring channel activity using patch-clamping - Not typical/required
Xenopus oocytes are used mainly to express exogenous genes. Knockout of endogenous homologs is not commonly done here. Knockout approaches are more relevant in model organisms like mice or zebrafish. Oocytes are chosen because of their low endogenous channel expression, making knockouts unnecessary in most cases.
Correct Combination:
The best combination of experiments for characterizing a K⁺ channel is:
A, B, and C → Option a
Final Answer: Option a: A, B, and C is correct.
