Mucopolysaccharides in eye are:
**Core Concept**
Mucopolysaccharides are complex carbohydrates that play a crucial role in maintaining the structure and function of various tissues, including those in the eye. They are composed of a core sugar molecule attached to one or more covalently bonded chains of sugar molecules.
**Why the Correct Answer is Right**
The correct answer is **D. Glycosaminoglycans (GAGs)**. Glycosaminoglycans are a type of mucopolysaccharide that are present in the eye, where they contribute to the structure and function of the cornea, lens, and vitreous humor. GAGs, such as hyaluronic acid and chondroitin sulfate, help maintain the hydration and transparency of the cornea and play a role in the regulation of intraocular pressure.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because GAGs are a specific type of mucopolysaccharide, whereas the question is asking for the broader category of mucopolysaccharides present in the eye.
* **Option B:** This option is incorrect because glycoproteins are a different class of molecules that contain carbohydrate chains attached to a protein core, whereas mucopolysaccharides are composed of sugar molecules only.
* **Option C:** This option is incorrect because proteoglycans are a type of molecule that contains a core protein covalently bonded to one or more GAG chains, whereas the question is asking for the mucopolysaccharides themselves.
**Clinical Pearl / High-Yield Fact**
Glycosaminoglycans, such as hyaluronic acid, play a critical role in maintaining the hydration and transparency of the cornea, and their depletion or abnormal accumulation can lead to corneal edema and vision loss.
**Correct Answer: D. Glycosaminoglycans (GAGs)**