Question

a mutation within a component of this signal transduction pathway prevents the activation of $g_{olf}$. which of the following scientific questions would best help researchers determine how the mutation prevents the activation of $g_{olf}$? choose 1 answer: a) does the mutation prevent ligand binding on the odorant receptor? b) does the mutation prevent the entry of cations through the cyclic-nucleotide-gated channel? c) does the mutation prevent the conversion of atp to camp? d) does the mutation prevent the activity of adenylate cyclase iii?

Explanation:

To determine how the mutation prevents \( G_{\text{olf}} \) activation, we analyze the olfactory signal transduction pathway. \( G_{\text{olf}} \) is a G - protein activated by the odorant - receptor complex.

• Option A: If the mutation prevents ligand (odorant) binding to the odorant receptor, the receptor - ligand complex won't form, and \( G_{\text{olf}} \) activation (which requires the activated receptor) will be prevented.
• Option B: The entry of cations through the cyclic - nucleotide - gated channel occurs downstream of \( G_{\text{olf}} \) activation (after cAMP is produced and opens the channel). So, a mutation affecting this channel doesn't directly relate to \( G_{\text{olf}} \) activation.
• Option C: The conversion of ATP to cAMP is catalyzed by adenylate cyclase, which is activated by \( G_{\text{olf}} \). So, this step is downstream of \( G_{\text{olf}} \) activation, and a mutation here doesn't affect \( G_{\text{olf}} \)'s activation.
• Option D: Adenylate cyclase activity is activated by \( G_{\text{olf}} \), so this is also a downstream event. A mutation affecting adenylate cyclase activity doesn't prevent \( G_{\text{olf}} \) from being activated.

So, the question in Option A directly addresses the initial step of the pathway that leads to \( G_{\text{olf}} \) activation.

Answer:

A. Does the mutation prevent ligand binding on the odorant receptor?