Lipids Flashcards
What structural component of lipids determines their function and why?
the polar head group (that is attached to the hydrophobic tails via a phosphodiester linkage) because it interacts with the environment
What characteristic of fatty acids determines their fluidity in membranes?
saturation
-saturated FA’s are less fluid
Why are saturated FA’s solid at room temperature?
because they stack easily due to presence of only sigma bonds in their hydrocarbon tails, have greater van der Waals foces, and have an overall more stable structure
Why are unsaturated FA’s liquid at room temperature
the presence of DB’s in the hydrocarbon tail introduces kinds into the chain which makes it difficult for them to stack and solidify… this is why unsaturated FA’s increase the fluidity of membranes
Glycerophospholipids (phosphoglycerides)
phospholipids containing a glycerol backbone with a phosphodiester bond to a highly polar head group
Phosphatidylcholine
glycerophospholipid with a choline head group
Phosphatidylethanolamine
glycerophospholipid with an ethanolamine head gorup
What are some membrane surface properties of glycerophospholipids?
cell recognition, signaling, and binding
Sphingoside backbone
glycerol with one of the hydroxyl groups replaced by an amine
4 major subclasses of sphingolipids
- Ceramides
- Sphingomyelins
- Glycosphingolipids
- Gangliosides
Ceramide
simplest sphingolipid with an amide head group
Sphingomyelins
sphingolipids that are phospholipids and have a phosphodiester bond in their head group
head groups include phosphatidylcholine or phosphatidylethanolamine
major components in the plasma membrane of cells containing myelin (oligodendrocytes and Schwann cells)
Glycosphingolipids
sphingomyelins with sugar head groups
mainly found on the outer surface of plasma membrane
Cerebrosides
glycosphingolipids containing a single sugar as their head group
Globosides
glycosphingolipids containing more than one sugar as their head group
Gangliosides
the most complex group of sphingolipids
polar head groups containing one of oligosaccharides with one or more N-acetylneuraminic acid (NANA aka sialic acid) at the terminus, and a negative charge
major role in cell interaction, recognition, and signal transduction
Isoprene
5 carbon moiety (C5H8)
Terpenes
class of lipids that are steroid precursors and are built from isoprene
How many isoprene units are in one terpene unit?
2
Steroids
4 ring structures (3 cyclohexanes and 1 cyclopentane ring)
Prostaglandins
autocrine and paracrine signaling molecules that regulate cAMP levels and have powerful effects on smooth-muscle contraction, body temperature, the sleep-wake cycle, and pain
What are the 4 fat-soluble vitamins?
A, D, E, K
Carotene
Vitamin A
What are two metabolic products of Vitamin A and their functions?
Retinal - vision
Retinoic acid - gene expression and epithelial dvlpmt
Cholecalciferol
Vitamin D
What is Vitamin D metabolized into and what does this metabolic product do?
Vitamin D is metabolized into Calcitrol in the kidneys
Calcitrol functions regulate calcium and phosphorus homeostasis in the intestines (increases calcium and phosphate absorption), promotes bone formation
A Vitamin D deficiency causes:
rickets
Tocopherol
Vitamin E
Vitamin E function
acts as biological antioxidant
aromatic rings destroy free radicals and prevent oxidative damage
Phylloquinone and Menaquinone
group of compounds that make up Vitamin K
What are two important roles of Vitamin K?
- important for the posttranslational modification necessary for the formation of prothrombin
- required for the introduction of calcium-binding sites on several calcium dependent proteins
Triacylglycerols
Lipids that contain one glycerol with three fatty acids attached via ester bonds
Why are TAG’s the preferred method of energy storage in the body?
Carbon atoms in lipids are more reduced than those in cabohydrates & TAG’s are the most reduced form of lipids in the body; thus, they provide twice as much energy per gram during oxidation
Free fatty acids
unesterified FA’s that travel in the bloodstream
Soaps
salts of free FA’s
Saponification
the ester hydrolysis of TAG’s using a strong base (such as NaOH or KOH)
