A mongooses immunity to cobra venom
In: Biology
Your nerves are covered in protein receptors that function like little locks. They also produce proteins, called neurotransmitters, that function like little keys which perfectly match the keyhole that the receptors have. When the correct neurotransmitter goes into a receptor, it “twists” and briefly causes a small hole to open up in the cell. This hole allows a small amount of electrolyte into the cell, which causes the cell to briefly turn on.
To prevent the cell from staying on perpetually, it has enzymes that break neurotransmitters down shortly after they enter a receptor. This causes the hole to close so electrolytes stops flowing in. The cell, meanwhile, is constantly pumping electrolytes out. Now that electrolytes can’t flow in, electrolyte levels in the cell go back to normal and it turns off.
Cobra venom contains a protein that fits into the “lock” on one of the important protein receptors on animal nerves. However, despite fitting the lock, the cobra venom protein doesn’t twist so no hole gets opened and the nerve doesn’t activate. The cobra venom protein is also different enough from the normal neurotransmitter that the nerve cell can’t break it down. This means that the cobra venom protein just sits in the protein receptor without doing anything – blocking it from being used by neurotransmitters.
If enough of this protein gets into an animal’s body, it blocks all of that animal’s neurotransmitters. When all of an animal’s neurotransmitters are blocked, its nervous system turns off. When an animal’s nervous system turns off, it stops breathing and dies.
Mongooses are immune to cobra venom because they have protein receptors with a very slightly different keyhole shape than other animals. That keyhole is still similar enough that the mongoose’s neurotransmitters can fit in it to function normally. However, its also different enough that cobra venom now just slightly doesn’t fit. Because the cobra venom can’t get into the mongoose’s protein receptors, it doesn’t have an effect on the mongoose.
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