Biochemistry Ch 5. Lipid Structure and Function Flashcards
Lipids
Insoluble in water and soluble in nonpolar organic solvents
Phospholipids
Amphipathic and form the bilayer of biological membranes, contain a hydrophilic (polar) head group and hydrophobic tails (non polar)
Phosphodiester linkage
Attaches hydrophilic head group of phospholipids
Phospholipid head group
Attached by a phosphodiester linage and determines the function of the phospholipid because it interacts with the environment
Saturation levels
The saturation of fatty acid tails determines the fluidity of membranes, saturated fatty acids are less fluid than unsaturated ones, fatty acids for most of the structural thickness of the phospholipid bilayer
Glycerophospholipids
Phospholipids that contain a glycerol backbone
Sphingolipids
Contain a sphingosine or sphingoid backbone, many are sphinophospholipids
Sphingophospholipids
Sphingolipids that are also phospholipids
Sphingomyelins
Major class of sphingophospholipids and contain a phosphatidylcholine or phosphatidylethanolamine head group, are the major component of the myelin sheath
Glycosphingolipids
Attached to sugar moieties instead of a phosphate group
Cerebrosides
Have one sugar connected to sphingosine
Globosides
Have two or more sugars connected to sphingosine
Gangliosides
Contain olifosaccharides with at least one terminal N-acetylneuraminic acid (NANA)
Waxes
Long chain fatty acids esterified to long-chain alcohols, used as protection against evaporation and parasites in plants and animals
Terpenes
Odiferous steroid precursors made from isoprene, a five carbon molecule
Monoterpene
One terpene unit, contains two isoprene units
Terpenoids
Derived from terpenes via oxygenation or backbone rearrangement, have similar odorous characteristics
Steroids
Contain three cyclohexane rings and one cyclopentane ring, their oxidation state and functional groups may vary
Steroid hormones
Have high affinity receptors, work at low concentrations, and affect gene expression and metabolism
Cholesterol
A steroid important to membrane fluidity and stability, serves as a precursor to a host of other molecules
Prostaglandins
Autocrine and paracrine signaling molecules that regulate cAMP levels, have powerful effects on smooth muscle contraction, body temperature, the sleep-wake cycle, fever, and pain
Fat soluble vitamines
Include A,D,E and K
Vitamin A
aka carotene, metabolized to retinal for vision and retinoid acid for gene expression in epithelial development
Vitamin D
aka cholecalciferol, metabolized to calcitriol in the kidneys and regulates calcium and phosphorus homeostasis in the intestines (increasing calcium and phosphate absorption), promoting bone formation, deficiency causes rickets
Rickets
Caused by vitamin D deficiency
Vitamin E
aka tocopherols, act as biological antioxidants, their aromatic rings destroy free radicals, preventing oxidative damage
Vitamin K
aka phylloquinone or menaquinones, important for formation of prothrombin (a clotting factor), performs post translational modifications on a number of proteins, creating calcium binding sites
Triacylglycerols
aka triglycerides, the preferred method of storying energy for long term use, contain one glycerol attached to three fatty acids by ester bonds, fatty acids usually vary, the carbon atom in lipids are more reduced than carbohydrates, giving two as much energy per gram during oxidation, very hydrophobic so they are not hydrated by body water and do not carry additional water weight, many stored in adipocytes
Adipocytes
Animal cells specifically used for storage of large triacylgylcerol deposits
Free fatty acids
Unesterified fatty acids that can travel in the bloodstream
Soaps
Salts and free fatty acids that can be synthesized in saponification, act as surfactants forming micelles
Saponification
Ester hydrolysis of triacylgylcerols using a strong base, like solid or potassium hydroxide
Micelles
Can dissolve a lipid soluble molecule in its fatty acid core and then wash it away with water because of its shell of carboxylate head groups
