Lipids

Question	Answer
Lipids contain...	fatty acids or a steroid nucleus
Lipids: properties	- soluble in organic solvents (eg acetone) but NOT in water
Triacylglycerols/fats	triesters fromed between glycerol and 3 long chain fatty acids - solid & mostly animal fats
waxes	esters formed between saturated fatty acids and long chain alcohols
Saturated fatty acids: properties	- molecules fit closely together in a regular pattern - strong attractions between fatty acid chains - high melting points that make them solids at room temperature
Classification of fatty acids	- saturated fatty acids contain only SINGLE bonds - unsaturated fatty acids contain cis C=C bonds - trans fatty acids have trans C=C bond
Unsaturated fatty acids: properties	- have nonlinear chains that do not allow molecules to pack closely - have low melting points - are liquids at room temperature
Prostaglandins contain...	20 C atoms in their fatty acid chains, derived from arachidonic acid
Prostaglandins are:	- produced by injured tissues - involved in pain, fever and inflammation - not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis
Olestra is...	- used in foods as an artificial fat - sucrose linked by ester bonds to several long-chain fatty acids - not broken down in the intestinal tract
Hydrogenation converts...	converts double bonds in oils to single bonds by adding hydrogen
Hydrogenation produces...	solid shortening, margarine, and other products
Hydrolysis	Triacylglycerols are split into glycerol and 3 fatty acids by water in the presence of an acid, a base, or an enzyme catalyst
Soaps are:	salts of fatty acids
Saponification	A reaction in which a tricylglycerol reacts with a strong base
Glycerophospholipids contain...	A glycerol backbone with 2 fatty acids at C1 & C2, and a phosphorylated alcohol attached at C3
Glycerophospholipids: examples & locations	- Lecithin & Cephalin - Abundant in brain & nerve tissues - Found in egg yolk, wheat germ & yeast
Sphingolipids are:	phospholipids that have an amide bond between a fatty acid and sphingosine (an 18 C alcohol)
Glycosphingolipids contain	monosaccharides bonded to the -OH of sphingosine by a glycosidic bond
Cerebrosides contain	only one monosaccharide
Steroids are...	lipids containing the steroid nucleus, which is a fused structure of four rings
Steroids: location	found in cholesterol, bile salts, hormones, and vitamin D
Cholesterol is a component of...	cellular membranes, myelin sheaths, and brain & nerve tissues
Cholesterol is composed of...	the steroid nucleus with methyl CH3 groups, an alkyl chain, and a hydroxyl group attached
Sterols serve as a precursor for the synthesis of steroid hormones such as...	- sex hormones (estrogen) - adrenocorticoids (cortisol) which regulate immunity - vitamin D (cholecalciferol) - bile salts (glycocholate) which are required for emulsification of fats
Sterols are transported in the blood in the form of...	High density lipoproteins (HDL) and low density lipoproteins (LDL)
Cholesterol is considered elevated if...	plasma cholesterol exceeds 200-220mg/dL
Cholesterol is synthesised where?	In the liver and also obtained from foods
Why are lipoproteins soluble in water?	Because the surface consists of polar lipids
How do lipoproteins differ?	In density, composition, and function
LDLs function	transport cholesterol to tissues to be used for the synthesis of cell membranes, steroid hormones, and bile salts
Why is LDL the "bad" cholesterol?	When the level of LDL exceeds the amount of cholesterol needed by the tissues, the LDLs deposit cholesterol in the arteries, which can restrict blood flow & increase the risk of heart attacks
HDLs function	Remove excess cholesterol from the tissues and carry it to the liver where it is converted to bile salts and eliminated.
Where are bile salts synthesised and stored?	Synthesised from cholesterol Stored in the gall bladder
Bile salts: function	Emulsify fats and oils to give a greater surface area for lipid digesting enzymes
Examples of bile salts	Sodium glycocholate Taurocholate
Gallstones are formed when...	large amounts of cholesterol accumulate in the gallbladder
Gallstones are composed of...	almost 100% cholesterol, with some calcium salts, fatty acids, and glycerophospholipids
Adrenal Cortiscosteroids are produced...	By adrenal glands located on the top of each kidney
Examples of adrenal corticosteroids	- Aldosterone which regulates electrolytes and water balance by the kidneys - Cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver
Anabolic steroids are derivatives of	testosterone
Anabolic steroids are used to...	illegally increase muscle mass
Anabolic steroids side effects	- fluid retention - hair growth - sleep disturbance - liver damage
What is the major dietary monounsaturated fatty acid?	Oleic acid (olive oil)
Lecithin functions	- one of the major phospholipids in cell membranes - most commonly used food emulsifier
Oxygenation causes what?	Rancidity
Oxygenation results in...	one oxygen per pair of C
Omega 3 example	Linolenic acid
Omega 6 example	Linoleic acid
Omega 9 example	Oleic acid
Glycosphingolipids examples	- gangliosides - cerebrosides
VLDL function	transport of endogenous triglycerides (bad cholesterol)
Chylomicron function	Transport of dietary triglycerides
Alkylosis & Acidosis: definition	- blood pH outside 7.35-7.45 - increased acidity = increased hydrogen - reduced acidity (more alkaline) = reduced hydrogen - interferes with oxygen transport
Peptides & Polypeptides contain	peptides = less than 10 amino acids polypeptides = more than 10
Are steroid hormones hydrophobic or hydrophilic?	Hydrophobic
Are protein hormones hydrophobic or hydrophilic?	hydrophilic
Thiols can contain...	disulfide bonds eg. keratin and casein
Polyunsaturated fatty acids contain..	two or more double bonds
In the type O cell membrane of the red blood cell in humans, the red blood cell surface has	A trisaccharide

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	Created by travel_bug about 11 years ago