Q.3 - Biology

Question

The deadly nerve gas Sarin irreversibly inhibits Acetylcholinesterase. What effect would Sarin have on muscle contraction? 

Step-by-Step Solution

Answer

Sarin acts by inhibiting the enzyme acetylcholinesterase. Ordinarily, this protein degrades acetylcholine released at the synaptic cleft. The acetylcholine activates nerve fibers that cause muscles to contract. If the neurotransmitter is not removed, the muscles don't relax.

Step 1. Introduction

Acetylcholinesterase

•  enzyme that breaks down ACh into acetyl and choline.

Sarin

• Sarin is an extremely toxic synthetic organophosphorus compound. A colourless, odourless liquid, it is used as a chemical weapon due to its extreme potency as a nerve agent. 

Step 2. Explanation

• In the presence of Sarin, acetycholine is not removed from the synapse, resulting in continuous stimulation of the muscle plasma membrane. 
• At first, muscle activity is intense and uncontrolled, but the ion gradients dissipate, so electrical signals in the T-tubules are no longer possible. 
• The result is paralysis, leading to death by asphyxiation.