Chapter 5 - Lipid Structure and Function Flashcards
Amphipathic
a molecule that has both hydrophilic and hydrophobic regions
Phospholipid
phosphate and alcohol make up polar head group, joined to hydrophobic FA tail by phosphodiester linkages
Lipid properties depend on:
the degree of saturation in fatty acid chains and the functional groups to which the fatty acid chains are bonded
Ceramide
simplest sphingolipid, has one hydrogen atom as its head group
Sphingomyelin
no net charge, major components in plasma membranes of cells producing myelin (oligodendrocytes and Schwann cells)
Cerebrosides
glycosphingolipids on outer surface of plasma membrane with a single sugar
Globosides
same as cerebrosides but have two or more sugars, no net charge
Gangliosides
glycolipids with polar head groups composed of oligosaccharides with one or more N-acetylneuraminic acid (NANA) molecules at the terminus, and a negative charge
Waxes
esters of long-chain FAs with long-chain alcohols
Terpenes
metabolic precursors to steroids, class of lipids built form isoprene (C5H8), a single terpene unit contains two isoprene units
Steroids
metabolic derivatives of terpenes, they have 4 cycloalkane rings fused together: three cyclohexane and one cyclopentane
What determines steroid functionality?
Oxidation status of the rings and functional groups present, they are nonpolar
Where are steroids secreted?
act as hormones, so secreted by endocrine glands into the bloodstream and travel on protein carriers to sites where they bind to specific high-affinity receptors and alter gene expression levels
What is the importance of cholesterol?
major component of phospholipid bilayer, mediates membrane fluidity, is amphipathic
What are prostaglandins?
made by almost all cells in the body, 20-carbon molecule of unsaturated COOH derived from arachidonic acid, contains one five-carbon ring
What is the function of prostaglandins?
paracrine/autocrine signaling molecules, regulates synthesis of cAMP
How do nonsteroidal anti-inflammatory drugs (NSAIDs) work?
they inhibit the enzyme cyclooxygenase (COX), which aids in the production of prostaglandins
What are some downstream effects of prostaglandins?
smooth muscle function, influence over sleep-wake cycle, elevation of body temp associated with fever and pain
Vitamin A (carotene)
unsaturated hydrocarbon for vision, growth and development, and immune function
Retinal
an aldehyde metabolite of vitamin A, component of the light-sensing molecular system in human eye
What is calcitriol?
biologically active form of vitamin D, increases calcium and phosphate uptake in the intestines for bone production
Vitamin E
tocopherols and tocotrienols, substituted aromatic ring with long isoprenoid side chain, hydrophobic nature
What is the function of tocopherols?
biological antioxidants, aromatic ring reacts with free radicals, destroying them
Vitamin K
group of compounds: phylloquinone and menaquinones
What is the importance of vitamin K?
vital for posttranslational modifications required to form prothrombin, the clotting factor in blood
Why are triacylglycerols specifically used for energy storage?
carbon atoms of FAs are more reduced than sugars, so oxidation yields twice the amount of energy per gram, and second they are hydrophobic, do not draw water and do not require hydration for stability—decreases weight
Micelles
tiny aggregates of soap with hydrophobic tails inward and hydrophilic heads outward, thereby shielding hydrophobic lipid tails allowing solvation
