Lipid Classification Flashcards

Lipid Classification

• Lipids are nonpolar molecules that serve three main roles: energy storage, cell structure (membranes), and as precursors to vitamins and hormones.

Fatty Acids

• Fatty acids are lipids that act as building blocks for more complex lipids.
• Typically contain an even number of carbon atoms and can be either saturated (with single bonds) or unsaturated (with double bonds).
• Release significant energy when C-H bonds are broken; commonly reach tissues as free fatty acids.

Triglycerides

• Composed of a glycerol backbone bonded to three fatty acid chains.
• Functions include energy storage, thermal insulation, and mechanical padding for organs.

Phospholipids

• Structurally similar to triglycerides but with one fatty acid replaced by a phosphate group, resulting in an amphipathic molecule (having both hydrophilic and hydrophobic properties).
• Play a critical role in forming biological membranes.

Glycolipids

• Contain one or more carbohydrates attached to glycerol, also making them amphipathic.
• Predominantly found in the membranes of myelinated cells within the nervous system.

Sphingolipids

• Based on an amino alcohol backbone with a long-chain fatty acid.
• Integral components of cell membranes and are associated with the ABO blood group antigens on red blood cells as glycosphingolipids.

Steroids

• Characterized by a four-ring structure composed of three cyclohexane rings and one cyclopentane ring.
• Includes hormones, cholesterol (crucial for membrane fluidity and stability), and Vitamin D.

Terpenes

• Built from two isoprene units (C5H8).
• Function as integral parts of body pigments, including Vitamin A, and serve as precursors for steroids and lipid signaling molecules.

Waxes

• Created through the ester linkage of long-chain fatty acids and long-chain alcohols.
• Exhibit water-repellent properties, protecting plants from evaporation and parasites and aiding in moisture retention in animals.

Prostaglandins

• Eicosanoids consisting of a 20-carbon unsaturated carboxylic acid and a five-carbon ring.
• Produced by nearly all body cells and function as local hormones affecting various physiological processes like blood pressure, body temperature, smooth muscle contraction, and sleep-wake cycles.

Adipocytes

• Specialized fat cells predominantly filled with triglycerides.
• Commonly found under the skin, around mammary glands, and within the abdominal cavity.

Vitamins Derived from Lipids

• Vitamin A (Carotene): A terpene that is converted into retinal, essential for vision.
• Vitamin D (Cholecalciferol): A steroid that is metabolized into calcitriol, facilitating calcium and phosphorus absorption for bone health.
• Vitamin E (Tocopherols): Known for its antioxidant properties, scavenging free radicals.
• Vitamin K (Phylloquinone and Menaquinones): Vital for prothrombin formation (a clotting factor) and the introduction of calcium-binding sites on certain proteins.

Saponification

• Refers to the hydrolysis of triglycerides using a base, resulting in soap formation—specifically, salts of free fatty acids.

Sphingosine

• An 18-carbon amino alcohol with an unsaturated hydrocarbon structure, featuring both an NH2 group and an alcohol group.