Which of the following is/are NOT amphipathic? Answers: A – E A Lipopolysaccharides B Glycerophospholipids C Triacylglycerols D Cholesterol E Sphingolipids
The correct answer and explanation is:
The correct answer is C: Triacylglycerols.
Explanation:
Amphipathic molecules are those that contain both hydrophilic (water-loving) and hydrophobic (water-fearing) regions. This property is crucial for the formation of biological membranes and the transport of lipids in aqueous environments.
Let’s go through each option:
- A. Lipopolysaccharides:
Lipopolysaccharides (LPS) are amphipathic molecules. They consist of a hydrophobic lipid component and a hydrophilic polysaccharide component, making them capable of interacting with both water and lipid environments. - B. Glycerophospholipids:
Glycerophospholipids, such as phosphatidylcholine, are classic examples of amphipathic molecules. They have a hydrophilic phosphate head group and two hydrophobic fatty acid tails. This dual nature is essential for the formation of lipid bilayers in cell membranes. - C. Triacylglycerols:
Triacylglycerols (also known as triglycerides) are not amphipathic. They consist of a glycerol backbone bound to three fatty acid chains, all of which are hydrophobic. This structure makes them non-polar and water-insoluble. They are primarily used for energy storage, not membrane structure. - D. Cholesterol:
Cholesterol is amphipathic. It has a hydrophobic steroid ring structure and a small hydrophilic hydroxyl group (-OH) at one end. This enables cholesterol to fit into lipid bilayers, influencing membrane fluidity. - E. Sphingolipids:
Sphingolipids, like sphingomyelins, are also amphipathic. They have a hydrophobic tail (fatty acid) and a hydrophilic head group (often a phosphate group), making them key components of cell membranes.
In summary, triacylglycerols (C) are not amphipathic, as they lack a hydrophilic region, unlike the other molecules listed.