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ch.21 Lipids

Lipids Heterogeneous class of naturally occurring organic compounds Insoluble in water but soluble in organic solvents like dichloromethane
Lipid Examples Fatty acids, triglycerides, sphingolipids, glycolipids prostaglandins, leukotrienes, thromboxanes Cholesterol, steroid hormones, bile acids
Function of Lipids: Storage & membrane components Storeage: 2x the energy of carbs by weight Membrane components: membranes divide aqueous cytoplasma into cells & intracellular compartments
Function of Lipids: Chemical Messengers Primary Messengers- signals from one part of the body to the other ex) steroid hormones, sex hormones Secondary Messengers- intracellular messengers ex) prostoglandins
Triglycerides A triester of glycerol with 3 fatty acids
Structure of Triglycerides 2 or 3 fatty acid components present hydrophobic character caused by long hydrocarbon chains The ester group is polar but buried in a non-polar environment, making triglycerides insoluble in water
2 kinds of Complex Lipids Phospholipids and Glycolipids Complex lipids form the membranes around cells and around small structures within cells
Phospholipids Contains an alochol, 2 fatty acids and phosphate Glycerophospholipids-alcohol is glycerol Sphingolipids- alcohol is sphingosine
Glycolipds Complex lipids that contain a carbohydrate
Complex lipids in aqueous solution spontaneously form into a lipid bilayer, a back to back arrangement of lipid monolayers (2 layers, tail to tail) The hydrocarbon tails in the interior can be rigid of rich in saturated fatty acids or fluid if rich in unsaturated fatty acids
Cholesterol *Most abundant & important steroid in body *A component in plasma membrane in all animal cells *the precursor of all steroid hormones & bile acids
What are lipoproteins? Carriers of cholesterol
High Density Lipoproteins (HDL) "good Cholesterol" consists of 33% protein & 30% cholesterol
Low density lipoprotein (LDL) "bad Cholesterol" contains 25% proteins & 50% cholesterol *leaks lipids that get stuck in blood vessles
Very Low density lipoproteins (VLDL) Carries Triglycerides(fats) synthesized by liver, Delivers fat cells for storage will morph into LDL eventually
Chyomicrons Carry dietary lipids synthesized in intestines
What is the starting material for the synthesis of steroid hormones? Cholesterol, it is converted first to progesterone and then to both sex hormones & adrenocorticoid hormones
Female sex hormones synthesized in the ovaries from progesterone
Prostaglandins family of compounds that have the 20-carbon skeleton of prostanoic acid * autocrine and endocrine hormones *mediate vasodilation, bronchodilation, neuron sensitization
Prostaglandins not stored in tissues but synthesized ... from membrane bound 20-carbon polyunsaturated fatty acids in response to specific physiological triggers ex) arachidonic acid
Thrombaxanes derived from arachodonic acid *induces platelet aggregation & vasconstriction *aspirin inhibits the synthesis of thromboxane by inhibiting the COX enzyme
COX-1 catalyzes the normal physiological production of prostaglandins
COX-2 responsible for production of prostaglandins in inflammation-reason why we take asprin
Which hormone inhibits further ovulation once an egg has been fertilized? progesterone
How many rings are associated with the steroid structure? 4
Which of the following transports cholesterol to the liver? HDL
Lipid membranes have how many layers? 2
What is the IUPAC name of glycerol? 1,2,3-propanetriol
In glycerophospholipids where is the phosphate group attached to glycerol? at a terminal carbon only
Which of the following has the largest percentage of cholesterol and cholesterol esters? LDL
Myelin, the coating of nerve axons, is what type of lipid? sphingolipid
Which of the following reactions is the source of trans fatty acids found in some processed food? Hydrogenation
Which of the following carries cholesterol to the cells? LDL
What is the function of a steroid hormone primary messenger? deliver signals from one part of the body to another
Which alcohol is a component of all triglycerides? glycerol
Which hormone triggers ovulation? luteinizing hormone
Which of the following is associated with thromboxanes? platelet clumping
Which of the following is used to define lipids? their insolubility in water
Which of the following is a function of unsaturated fatty acids in membranes? they give the interior of the membrane liquid like structure
What do we mean by an essential fatty acid? a fatty acid which must be part of our diets since we cannot synthesize it
Which of the following describes the distribution of the polar & nonpolar portions of lipids in the lipid bilayer? both polar heads are on the outside of the bilayer and both hydrophobic tails are on the inside of the bilayer
Which of the following is the result of high cholesterol levels inside cells? less LDL is taken into the cells from the plasma
Asprin and other NSAIDs do which of the following? inhibit both COX-1 and COX-2 activity
Where in the body are leukotrienes most commonly found? White blood cells
Created by: aoyler



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