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Nutrition-HED3313-Exam 1 Review

Terms in this set (89)

1. Triacylglycerols (fats and oils)
Structure: Made from 1 glycerol + 3 fatty acid tails = tri-acylglycerol
Example: Fats: Butter, lard Oils: Corn oil, olive oil, margerine
Function: Energy storage & Cushions and insulates the body and nerves.
2. Diacylglycerides (phospholipids): lipid bilayers (the plasma membrane of every cell and the membranes within eukaryotic cells)
Structure - similar to a triacylglycerol, but has only 2 fatty acid tails, and in addition has a phosphate group = (1 glycerol, 2 fatty acids, and a -PO4)
The -PO4 makes the glycerol "head" water soluble, or hydrophilic.
The long hydrocarbon tail is hydrophobic.
Function: Due to this "amphipathic" nature (both water-loving and water-hating regions in a single molecule), phospholipids self assemble into bilayers that shield the tail from water = forming membranes (phospholipid bilayers!).
3. Steroids: (cholesterol, steroid hormones)
Structure: Considered to be a "cousin" of fats - and are made from lipids. Have no fatty acids in their structure, but are very hydrophobic , see Fig 3.10b in your book
Functions of Chloesterol:
(1) Help to maintain membrane fluidity, pliability and resilience in membranes of animals, which have high amounts or rigid, saturated fatty acids.
(2) Sex hormones (testosterone, estrogen and progesterone) are all made from cholesterol
Cholesterol gets a 'bad rap" in our diet, but has CRUCIAL roles in the functioning of our cells - we couldn't live without cholesterol!!!
However, too much cholestereol in the diet is known to be a factor in atherosclerosis and heart disease.
Cholesterol circulates in the bloodstream bound to carrier 'lipo-proteins'. High Density Lipoprotein (HDL - the "Good" kind) carries blood cholesterol to the liver where is can be eliminated from the body. Low Density Lipoprotein (LDL - the "Bad" kind) deposits blood cholesterol in the artery walls, where it can lead to constriction of blood vessels,heart disease, heart attacks, etc