Lipids are a diverse group of molecules that contribute to energy storage, nutrition, and the structure of cells. This lesson focuses on fatty acids, triglycerides, and phospholipids, emphasizing how their structures determine their properties and biological roles.
A fatty acid consists of a long hydrocarbon chain ending in a carboxylic acid group. The hydrocarbon chain is nonpolar, so fatty acids are generally hydrophobic and do not mix readily with water.
All flashcards
What is a fatty acid?
A lipid with a long hydrocarbon chain ending in a carboxylic acid group. Its nonpolar chain makes it generally hydrophobic.
How do saturated and unsaturated fatty acids differ?
Saturated fatty acids have only single carbon-carbon bonds and the maximum number of hydrogen atoms. Unsaturated fatty acids have one or more double bonds, fewer hydrogen atoms, and bends in their chains.
What is a triglyceride?
A lipid formed when three fatty acids link to one glycerol molecule. Triglycerides are hydrophobic and serve as efficient energy-storage molecules.
What does amphipathic mean for a phospholipid?
It means the molecule has both a hydrophilic region, its phosphate-containing head, and a hydrophobic region, its fatty acid tails.
How are phospholipids arranged in a lipid bilayer?
They form two layers with their hydrophobic tails facing one another and their hydrophilic heads exposed to water on the outer surfaces.
Quiz questions
How does the energy provided by metabolizing triglycerides compare with the same amount of carbohydrate or protein?Answer: It can provide more than twice as much energy.
Which properties are typical of waxes?Answer: They resist water and are typically hard at room temperature.
What structural feature defines a sterol?Answer: It is a steroid that has a hydroxyl group.
What is a membrane-strengthening role of cholesterol?Answer: It strengthens membranes in eukaryotes and some bacteria without cell walls.
What is a typical effect of topical hydrocortisone?Answer: It reduces local inflammatory symptoms, including itching and rashes.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.