Which type of eicosanoid is a modified fatty acid with a single five-carbon ring?
A Phospholipid
B Steroid
C Triglyceride
D Prostaglandin
The correct answer and explanation is:
The correct answer is D) Prostaglandin.
Prostaglandins are a type of eicosanoid, which are biologically active lipid compounds derived from fatty acids. They are produced by the enzymatic conversion of arachidonic acid, a polyunsaturated fatty acid, by the enzyme cyclooxygenase (COX). Prostaglandins are characterized by having a five-carbon ring structure, which differentiates them from other eicosanoids, such as leukotrienes or thromboxanes.
The five-carbon ring in prostaglandins is part of the core structure that defines them, and they play a key role in various physiological processes. These include inflammation, blood clotting, regulation of blood pressure, and the induction of labor. The presence of the ring and the modifications to the fatty acid chain contribute to their biological activity.
Prostaglandins act by binding to specific receptors on target cells, initiating signaling pathways that lead to diverse effects, such as pain, fever, and the regulation of blood flow. They are produced in response to injury or infection and help mediate the inflammatory response. Because they are produced locally and have short-lived effects, prostaglandins are considered autocrine or paracrine signaling molecules, meaning they affect the cells that produce them or nearby cells.
In summary, prostaglandins are modified fatty acids with a five-carbon ring, making them distinct among the eicosanoids. Their biological functions are critical in many aspects of human health, particularly in inflammatory and immune responses.