Describe the unique properties building-block molecules and biological importance of the three important groups of lipids fats phospholipids and steroids?

Answer 1

III. Lipids are diverse group of hydrophobic molecules, all hydrophobic; includes waxes and pigments not discussd A. Fats - not polymers, large molecules assembled from smaller molecules - glycerol and fatty acids 1. glycerol = alcohol w/ 3 C, each with a OH group 2. fatty acid = long C skeleton, 16-18 C long (fig 5.11) a. carboxyl group at end b. long chain of hydrocarbons - C-Hbonds are nonpolar, producing hydrophobic molecule c. 3 fatty acids join to the carbon skeleton, making a triglyceride, aka triglycerol d. fatty acids attached to the chain can be the same or different e. if there are no double bonds btn C, chain is straight - saturated fatty acid - solid =fats f. if double bonds occur, chain is kinked- unsaturated - will be liquid = oils g. cis bonds vs. trans bonds in hydrogenated products 1. trans fats in hydrogenated products may contribute more to atherosclerosis than saturated fats h. fat is very useful - a gram of fat stores more than 2x as much energy as a gram of polysac 1. compact storage for animals on the move (Plants don't have to move) 2. storage, warmth and cushioning B. Phospholipids -similar to fat, but only 2 fatty acids 1. 3rd hydroxyl group of glycerol attaches to negatively charged phosphate group (Fig. 5.13) a. other small charged molecules can attach to phosphate group to form phospholipids 2. head is hydrophilic, tail is hydrophobic (fig 5.14) a. in water, phospholipids self assemble into bilayers to shield hydrophobic portions from H2O 3. cell membranes are made of this, form a boundary btn cell and environment that is semipermeable C. Steroids - lipids w/ 4 fused rings for C skeleton (f.g 5.15) 1. functional groups vary 2. cholesterol a. common in cell membranes b. precurser of other steroids, eg. sex hormones and other hormones c. cholesterol is important, too much is bad

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Answer 2

Fats are long hydrocarbon chains that store energy in cells. Phospholipids consist of a hydrophilic phosphate head and hydrophobic fatty acid tails, forming cell membranes. Steroids have a four-ring structure and are important for signaling and hormone production in the body. Each group plays a crucial role in various biological processes such as energy storage, cell structure, and cell signaling.