Of the following Exotoxins are –
**Core Concept**
Exotoxins are a group of potent toxins produced by certain bacteria, primarily Gram-positive bacteria such as Clostridium, Corynebacterium, and Bacillus species. They are secreted into the surrounding environment and can cause a range of systemic effects, including muscle paralysis, respiratory failure, and even death.
**Why the Correct Answer is Right**
Exotoxins work by binding to specific receptors on the surface of host cells, leading to the activation of various signaling pathways that ultimately result in cell death. For example, botulinum toxin, an exotoxin produced by Clostridium botulinum, binds to the SNARE protein on the surface of neurons, preventing the release of acetylcholine and causing flaccid paralysis. Other exotoxins, such as tetanus toxin, work by blocking the release of neurotransmitters, leading to muscle rigidity and spasms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the type of toxin or its mechanism of action.
**Option B:** This option is incorrect because it refers to endotoxins, which are lipopolysaccharides found in the outer membrane of Gram-negative bacteria, rather than exotoxins.
**Option C:** This option is incorrect because it refers to a different type of toxin, such as a virulence factor or a bacterial enzyme.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that exotoxins are highly potent and can cause severe systemic effects, even at low doses. This is because they can bind to specific receptors on host cells, leading to a cascade of downstream effects that can be difficult to reverse.
**Correct Answer:** C. Tetanus toxin is an example of an exotoxin.