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175 Cards in this Set
- Front
- Back
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lipids are biological substances which are soluble in organic, non-polar solvents such as...
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ether
benzene chloroform |
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examples of lipids...
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fatty acids
triglycerides phosphoglycerides cholesterol |
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lipids consist primarily of...
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hydrocarbon chains
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which yeilds more energy? lipid (FA) or disaccharide both with 12 C? why?
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lipid, is more highly reduced
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major biological role of lipid...
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energy storage and atp production
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why do animals sotre their energy mainly as lipid and not carb?
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mobile - lipids more energy and light weight
stored almost anhydrously (less water) |
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other important biological roles of lipids:
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structure - cell membranes
regulation - steroid hormones emulsification - bile salts surfactant electron carriers - CoQ |
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some biologically important types of lipids...
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fatty acids, glyceryl esters (glycerides and phosphogylcerides), cholesterol and derivatives
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carbons in short, medium, and long FA?
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short, 2-4
medium, 6-12 long, >12 |
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number of double bonds in FA?
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can have none, one, or many (saturated, monounsaturated, and polyunsaturated)
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delta numbering
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start at carboxyl carbon
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w or n numbering?
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start at w terminus
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letter designation
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starts at carbon adjacent to the carboxyl carbon
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what is the descriptive name of a saturated FA with 12 c's?
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lauric
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what is the descriptive name of a saturated FA with 14 c's?
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myristic
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what is the descriptive name of a saturated FA with 16 c's?
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palmitic
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what is the descriptive name of a saturated FA with 18 c's?
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stearic
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what is the systematic name of a saturated FA with 12's c's
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dodecanoic
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what is the systematic name of a saturated FA with 14 c's?
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tetradecanoic
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what is the systematic name of a saturated FA with 16 c's?
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hexadecanoic
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what is the systematic name of a saturated FA with 18 c's?
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ocatdecanoic
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what is the descriptive name of a unsaturated FA with 16 c's?
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palmitoleic
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what is the descriptive name of a unsaturated FA with 18 c's
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oleic, linoleic, linolenic
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what is the systematic name of a unsaturated FA called oleic?
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9-octadecadienoic
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what is the systematic name of a unsaturated FA with 16 c's
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9- hexadecenoic
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what is the systematic name of a unsaturated FA called linoleic?
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9,12-octadecadienoic
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what is the systematic name of a unsaturated FA called linolenic?
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9,12,15-octadecatrienoic
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delta system _:_delta_
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number of carbons:number of double bonds delta position of double bonds form coo-
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omega systen _:_omega_
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nubmer of carbons: number of double bonds omega- position of frist double bond from ch3
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some unsaturated FA's with double bonds at omega-3 or omega-6 are...
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essential FA's
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why are omega 3/6 FA's important?
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some are components of of cell membranes after incorporation into more complex lipids
synthesis of prostaglandins and related molecules used in regulation |
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what percentage of daily caloric intake should be omega-6?
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5%
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what percentage of daily caloric intake should be omega-3?
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1%
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good source of omega-6?
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corn oil
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good source of omega-6?
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corn oils
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amphipathic
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both hydrophobic and hydrophilic components
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because FA's are amphipathic, they are
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good detergents
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surfactant activity
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decreases the surface tension between h20 and air
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emulsifying activity
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break a big insoluble lipid droplet into many smaller h20 suspendable droplets
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making soap involves releasing fatty acids form triglycerides by...
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alkaline hdrolysis
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saponification
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heat at a basic pH and h20 with triglyceride produces glycerol and fatty acid salts
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Biological FA funcitons;
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metabolic fuel
energy transport precursors of prostaglandins, leukotrienes, and thromboxanes anchorage of proteins to membranes components of more complex lipids |
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FA function; energy transport form?
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in complex with serum albumin
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prostaglandins, leukotrienes, adn trhomboxanes
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eiconsonoids
20 C's all involved in regulation |
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FA function; componenets of more complex lipids:
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glycerides
phosphoglycerides sphingolipids (membrane lipids) |
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glycerol and FA and NTP =
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monoglyceride, ndp and pi
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major function of monoglycerides
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metabolic intermediates
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major function of diglycerides
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metabolic intermediates
reulation |
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major function of tri glycerides
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energy storage, transport insulation
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the most common class of dietary lipids?
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triglycerides
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deitary lipids can be
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fats or oild
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fat
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TG's solid at room temp
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oils
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TG's liquid at room temp
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what determines viscosity of TG's
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temperature
degree of saturation length of acyl gorups |
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which is more likely liquid? TG's with saturated or unsaturated FA's
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unsaturated
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why TG's with saturated FA's more solid?
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easier to pack, more interaction between chains
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Plant/animal TG's more saturated/ unsaturated?
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plants - unsaturated
animal - saturated |
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olive oil
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20% sat. 80% unsat
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butter
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60% sat. 40% unsat.
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margarine is sythesized from? in a process involving?
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plant oils
hydrogenation conversion of cis to trans double bonds |
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phosphogylcerides are made of
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2 fa's
glycerol phosphate |
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phosphatidic acid
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the simplest phosphoglyceride, rare in nature
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phosphates of phophoglycerides are often linked to groups (x's) like...
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choline
ethanolamine inositol glycerol serine others |
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phosphoglyceride naming
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phosphatidyl ___x____
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phophatidylcholine is also called
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lecithin
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phosphoglycerides are amphipathic so can form...
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monolayers - surfactants
micelles - emulsify bi-layers (unlike FA's) |
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phosphoglyceride shape
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cylindrical
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FA's shape
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conical
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FA micelle shape
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spherical
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ppg micell shape
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bilayer component
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agitation of ppg monolayer results in...
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micelle with bilayer and then liposome
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lipid bilayers act as a barrier to
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charged or polar molecules
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carbs in the plasma membrane are often involved with
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recognition
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bio membrane % protein/bilayer
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50-50
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major roles of PG's
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membrane component
regulation component of bile component of surfactant on alveoli transport; metabolic fuel |
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phophatidylinositol
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membrane lipid
mediates response to epinephrine |
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cholesterol functions
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membrane component
precursor of steroid hormones precursor of bile acids not usable as a fuel by animal cells |
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most lipid digestion takes place in
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the small intestine
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steps of lipid digestions
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emulsification
hydrolysis of ester bonds catalyzed by lipases |
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lipases made in the pancrease and secreated into the sm intestine
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pancreatic lipase
cholesteryl esterase other lipases |
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bile
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PG and bile salt
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pancreatic lipase catalyzes the reaction
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TG and h20 to 2-monoglyceride and 2 FA's
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cholesteryl esterase catalyzes the reaction
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cholesterol ester and h20 tto FA and Cholesterol
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amphipathic products of lipid digestion aggregate with
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bile components to form mixed micelles
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products of lipid digestion must be take up by
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mixed micelles to be absorbed
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lipid uptake by intestinal cells is active or passive
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passive
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after apsorption, dietary monoglycerides and cholesterol are
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re-esterified to dietary fatty acid to form triglycerides in smooth ER
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lymphatics lead to
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subclavian vein
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chylomicrons contain
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major protien - apolipoportein B-48
lipid |
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lipid components of chylomicrons
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triglyceride 85%
cholesterol ester and cholesterol - 5% phosphoglycerides - 8% |
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free FA's taken up my intestinal cells and release to the hepatic portal vein are what length?
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short or medium chain
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where is LPL
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capillary walls
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what does LPL do
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digests tG to glycerol andFA
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Fa in general circ used by
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many cells esp muscle and adipocytes
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glycerol in gen circ used by
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mostly liver
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chylomicron remnants in gen circ are taken up by
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liver
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the liver used cholesterol in
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other lipoproteins and excretes excess in bile salts
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chylomicrons reminants contain
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lots of cholesterol and little TG
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lipases that catalyze the digestion of TG
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pancreatic lipase
LPL adipocyte lipase |
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pancreatic lipase function
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dietary TG in sm intestine to Fa and 2 monoglycerides
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adipocyte lipase function
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stored tB in adipocytes to FA and diglyceride
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other adipocyte enzymes hydrolyze diglyceride to
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glycerol and free fatty acids
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free fatty acids
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circulate in the blood as albumin complexes are taken up by amny different cell ytpes
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glycerol in blood circulation
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is taken up primarily in the liver
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the activity of adipocyte lipase is controlled by
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glucagon +
epinephrine + insulin - |
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before FA can be oxidized they must activated by
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acylcoa synthetase
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sythatases
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require ntp's
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sythases
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no ntp
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5 form of acyl coa synthatase
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short chain specific
mediu chain specific long chain specific very long chain specific non-specific gtp dependent |
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the most common acyl coa synthetase is
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long chain specific
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long chain specific is located
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either outer surface of ER or outer surface of outer mito mem
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acyl carnitine
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(derived from lys and met) transports long chain fatty acyl groups across the inner mito mem
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cpt1
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sythesizes acyl carnitine from acyl coa and carnitine
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does import of med/short chain require carnitine?
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no
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do unsaturated FA's yield the same # of atp as saturated?
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no
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3cis 2trans aceyl coa isomerase used to cope with a double bond..
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no fadh2 is made
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2,4 dienoyl coa reductase is used to cope with a double bond...
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nadPh is invested
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what cells can't carry out beta ox?
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rbc's
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can brain cells carry out beta ox?
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yes, but acess to FA's is limited, don't cross bbb
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only in the liver can acetyl coa be used to make?
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ketone bodies
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acetoacetate and beta dyrosybutyrate are usable as fuel by
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some cells but not the liver
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acetone is usable by which cells
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none, excreted
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ketone bodies are produces by the liver when
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glucagon/insulin ratio is high during fasting or in an uncontrolled type 1 diabetic
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high glucagon/insulin ration results in
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release of FA form the adipocytes
inhibits glycolysis and stimulates gluconeogenesis in the liver |
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high g/i ratio effect on cac
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slows
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slow cac results in what effect on beta ox of FA in mito
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decrease beta ox
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advantage of liver cells in making KB's when high g/i?
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regerates coash for use in beta ox
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KB are important fuels for...
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brain and muscle under conditions that promote kb sythesis(low blood glu, and low i/g ratio)
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during fasting, insulin levels are
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decreased
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GLUT4
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glucose transport protein upregulated by insulin
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where does kb utilization occur?
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mito matrix of brain, muscle (skeletal and cardiac), and renal cortex
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fuel source used by brain normally
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100% carbs
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fuel source used by brain during starvation
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20% carbs 80% kb
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advantages of kb use during starvation
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conserve glucose for rbc's
decrease muscle protein degredation |
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disadvantages of kb use during starvation
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decrease blood pH to life threatening levels
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FA's are synthesized from
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acetyl coa
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sources of acetyl coa for fatty acid syn?
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carbs mostly and some amino acids
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most acteyl coa used for FA syn is generated in the
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mito matrix
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enzymes that catlyze teh sythesis of FA's from acteyl coa are located in the
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cytosol
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how does acetyl coa cross the inner mito mem?
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combines with oaa to form citrate which can cross
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how is acetyl coa carboxylase hormonally controlled?
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insulin increases activity and glucagon decreases activity
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ix acetyl coas carboxylase more active when phosphorylated or de phosphorylated?
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dephosphorlyated
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FAS characteristics
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dimer of two identical monomers
7 different enzymatic activities per monomer contains one acyl carrier protein per monomer |
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enzymes of the FAS
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acetyl coa acp transacetylase
malonyl coa acp tranacylase beta ketoacyl sythase beta ketoacyl reducatse beta hydroxyacyl dehydrogenase enyl reducatse thioesterase |
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Where does sythesis of unsat FA from sat FA occur?
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ER
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sythesis of unsat FA from sat FA requires?
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desaturases
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desaturases
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mixed function oxidase activity (enz catlyze 2 substrate that are oxidized in same rxn)
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FA can be incorporated into more complex llipids:
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TG
PG sphingolipids |
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TG sythesis occurs in
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liver adipoctyes and intestinal cells
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acyl carnitine inhibits
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PDH
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malonyl coa inhibits
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CPT-1
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perhydrocyclopentanophenanthrene
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steroid
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cholesterol is a
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sterol
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sterols are steroids that have
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a hydroxyl group at C3
a hydrocarbon chain on C17 |
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regions of cell membranes enriched in choesterol form
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thicker microdomains that move like rafts among membrane phosphoglycerides
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a given microdomain often contains
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functionally related proteins
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association with the same microdomain probably increases teh likelihood that these funtionally related proteins will come in contact with each other which will
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increase functional efficiency
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mechanism of steroid hormone aciton
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cross cell and nuclear mem to bind receptor in nucleus that activates DNA transcription
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bile salt
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deprotonated bile acid
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cholestrol sources
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dietary - animal product
endogenous synthesis |
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cholesterol sythesized from
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acetyl coa
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most non hepatic cells get majority of cholesterol from
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LDLs
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Liver cells synthesize large amounts of
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cholesterol
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cholesterol is used by the liver for
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cell membranes (like all cells)
bile acids and VLDLs (only liver) |
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VLDLs
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protein
TG CE |
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how does vldl become ldl
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TG's digested to FA and gylcerol by LPL, changes type of apolipoprotein
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cholesterol biosynthesis
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cytosolic
all 27 C's from acetyl coa nadph provides most of reducing power atp is required intermediates make other molecules |
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key regulatory enz of cholesterol synthesis
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HMG coa reductase
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drugs that inhibit HMG coa reductase
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statins (structurally similar to HMG reductase = competative inhibitor)
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cholesterol excretion
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excreted as components of bile salts
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excess cholesterol
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incorporated into cell membranes, picked up by hdl and returned to liver
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cholesterol excreted as
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acidic sterols: bile acids/salts
neutral sterols: cholesterol, cholestanone, cholestanol, coprostanol |
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all hydroxyl groups of cholesterol are
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alpha and below the plane of the ring
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how much bile salt excreated is reabsorbed
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95%
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enterohepatic circulation
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recycling of bile acids/salts between intestine and liver
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