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250 Cards in this Set
- Front
- Back
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what are lipids?
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a group of structurally and functionally diverse biomolecules that don't dissolve in water. made in living systems by biochemical reaction.
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what in the liver can we use to make fat?
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carbohydrate
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if tehre is no room to store glycogen, then what?
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we make fat
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what is the recommended calorie intake for men?
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2900
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what is the recommended calorie intake for women?
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2200
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what makes up the most weight in our body?
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fat, 85%
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how much muscle glycogen is in the body in relation to fat?
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100 times more fat than muscle glycogen
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what are the two main features of fatty acids?
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carboxylic acid group and a long hydrocarbon chain
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how long is the hydrocarbon chain in fatty acids?
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4-30 carbons; 12-24 is more common
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what are other hallmark characteristics of the fatty acid hydrocarbon chain?
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linear, contains even number of carbons
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what properties do saturated fatty acids have?
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free rotation, mp, solubility
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what kind of fatty acids are te most prevalent in the human body?
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fatty acids with one double bond
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are fatty acid double bonds usually cis or trans?
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cis
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what is it called when cis double bonds occur at three-carbon intervals?
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divinylmethane pattern
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what ist he carboxyl reference number?
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carbons: double bond ratio
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where do trivial names come from?
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derive from a common source of the compound or the source from which it was first isoalted
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where does palmitic acid come froM?
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palm oil
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where does oleic acid come from?
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olive oil (oleum)
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where does stearic acid come from?
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"solid" in greek, solid at room temperature
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arachidonic acid
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arachnids in latin, mean spiders. they have arachidonic acid.
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what does the omega reference system do?
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indicates the # of carbons, # of double bonds and position of double bonds closest to omega carbon.
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what does the carboxyl-reference system indicate?
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the @ of carbons, # of double bonds, counting from carboxyl carbon (which is 1)
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what does omega-3 mean?
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omega is the last carbon, furthest from the carbonyl. 3 means the 3rd carbon with omega counting as 1.
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what are neutral glycerides?
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ester of glycerol and a fatty acid.
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what is the principal function of a neutral glyceride?
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energy storage, as in fat
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what is another name for phosphoglyceride?
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glycerophospholipids
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what are phosphoglycerides?
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lipids that contain a phosphate group
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what are phosphoglycerides used for?
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production of cell membranes, emulsifying agents
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why can phosphoglyceries not be stored as droplets?
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charged, it would be dragged away by water
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what is excess acetyl CoA converted to in humans?
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fatty acid esters
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where does fatty acid synthesis occur?
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cytoplasm
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where does fatty acid degradation occur?
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mitochondria
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what is the point of attachment during fatty acid synthesis?
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an acyl carrier protein (ACP)
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where specifically does fatty acid synthesis occur?
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in a multienzyme complex called fatty acid synthase
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what molecules are produced with fatty acid degradation?
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NADH and FADH2
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what molecule is used for fatty acid synthesis?
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NADPH
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what are the four main steps of fatty acid synthesis?
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condensation, reduction, dehydration, reduction
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what are the starting products of fatty acid synthesis?
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acetyl unit and malonyl unit
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wat is malonyl coA made from?
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acetyl CoA and bicarbonate (HCO3)
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is the formation of malonyl CoA reversible or irreversible?
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irreversible
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what enzyme catalyzes the synthesis of malonyl coA>
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acetyl CoA carboxylase
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what prosthetic group does acetyl CoA carboxylase contain?
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biotin, which links to the E amino group of a lys residue
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what activates the synthesis of malonyl CoA?
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citrate
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what inactivates the synthesis of malonyl coA?
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long-chain acyl-CoA
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What is the first step of malonyl CoA synthesis?
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biotin carboxylation
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what is the second step of malonyl CoA synthesis?
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carboxyl transfer via a transcarboxylase site
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what is needed for palimate synthesis?
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1 acetyl CoA and 7 malonyl Coa, and repeating fatty acid synthesis 7 times.
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what is palimate?
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a 16:0 long-chain saturated fatty acid
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does ATP favor or inhibit fatty acid synthesis?
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favor
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where are fatty acids made?
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cytosol
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where are fatty acids modified?
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smooth ER
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Where does elongation occur, and what are its substrates?
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smooth ER, palmitoyl CoA and malonyl Coa
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Where does desaturation occur, and what are its substrates?
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smooth ER, stearoyl CoA, O2, NADPH, Cyt B5
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what is the effector of a thioester and by what mechanism does it act?
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palmitoyl CoA, allosteric
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what is the effector of phosphorylation and by what mechanism does it act?
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ATP, conformational change
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what is the mechanism effect of citrate?
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allosteric
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what is substrate availability in fatty acid synthesis?
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availability of acetyl groups in the cytoplasm, supplied by citrate
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what is the key enzyme of fatty acid synthesis?
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acetyl CoA carboxylase
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what is acetyl CoA carboxylase activated by allosterically?
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citrate
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what is acetyl CoA carboxylase activated by covalently?
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dephosphorylation
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what is acetyl CoA carboxylase inhibited by allosterically?
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palmitoyl CoA
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what is acetyl CoA carboxylase inhibited by covalently?
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phosphorylation
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what is the source of glycerol for triglyceride for intersinal mucosa?
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2-monoacylglycerol
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what is the source of glycerol for triglyceride in other tissues?
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glycerol-3-phosphate
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which tissue has phosphatidic acid intermediates, intestinal mucosa or other tissues?
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other tissues
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where is glycerol kinase present?
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high in liver
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where is glycerol kinase NOT present?
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adipose
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where is glycerol-3-P dehydrogenase present?
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liver
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where is glycerol-3-P dehydrogenase present in high concentrations?
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adipose
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what are the general structures of glycerophospholipids?
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alkyl chains of long-chain fatty acids
choline ethanolamine inositol serine |
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what is the enzyme deficiency in niemann-Pick disease?
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sphingomyelinase
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what lipid accumulates in Niemann-Pick disease?
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sphingomyelin
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what is the enzyme deficiency in Gaucher disease?
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glucocerebrosidase
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what lipid accumulates in Gaucher disease?
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glucosylceramide
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what is the enzyme deficiency in Tay-Sachs disease?
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hexosaminidase A
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what lipid accumulates in Tay Sachs disease?
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ganglioside GM2
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What are eicosanoids?
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a group of molecules derived from the C20 fatty acid, arachidonic acid
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Which cells DO NOT synthesize eicosanoids?
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erythrocytes
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Where do eicosanoids function?
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locally at the site of synthesis
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What are examples of eicosanoids?
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PGE2, TXA2, LTA4
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What enzymes aid in the conversion of Arachidonic acid to eicosanoids?
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cyclooxygenase (COX) and Lipoxygenase
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What are the four stages of biosynthesis of cholesterol?
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1. Condensation
2 and 3. formation of Isoprene Unit and polymerization 4. cyclization and transformation |
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what is the precursor for formation of cholesterol?
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acetyl CoA
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What happens in step 1, condensation in cholesterol synthesis?
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formation of the intermediate mevalonate from acetate.
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what activates and inactivates condensation step in cholesterol synthesis?
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insulin activates it
glucagon inhibits it. |
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what is involved in step 2 of cholesterol biosynthesis?
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formation of Isoprene Units from mevalonate with 3 p hosphate groups from ATP.
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what is involved in step 3 of cholesterol biosynthesis?
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polymerization. six activated isoprene units are condensed to from squalene.
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What is involved in step 4 of cholesterol biosynthesis?
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conversion of squalene to the four-ring steroid nucleus, aka cyclization.
epoxide -->lanosterol --> cholesterol |
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what are the refining steps in cholesterol biosynthesis?
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reduction and isomerization, removal of 3 carbons
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what are the 3 main fates of cholesterol?
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biliary cholesterol, bile acds, or cholesteryl esters
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how are cholesteryl esters formed?
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in the liver through cyl CoA-cholesterol acyl transferase (ACAT). it catalyzes transfer of a fatty acid from co-enzyme A to hydroxyl group of cholesterol
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where are cholesteryl esters transported?
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in secreted lipoprotein particles to other tissues that use cholesterol, or stored in the liver.
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what is LACT?
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lecithin cholesterol acyltransferase
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what does LCAT do?
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catalyzes the fromation of cholesteryl esters from lecithin (phosphatidylcholine) and cholesterol.
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where are cholesteryl esters fromed by lcat stored?
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in the blood as lipoproteins
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what are chylomicrons?
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largest and least dense lipoproteins. have high proportion oof triacyhlglycerols.
synthesized in the ER of epithelial cells of small intestines. carry dietary fatty acids to tissues where they will be consumed or stored. |
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where do the remnants of chylomicrons go?
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the liver
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when is VLDL formed?
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when the diet has more fatty acids than needed. they are converted to triacylglycerols in the liver and packaged with apolipoproteins into VLDLs.
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what do LDLs do?
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carry cholesterol to extrahepatic tissues
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where do HDLs originate?
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originate in the liver and small intestines
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what is the function of apoA?
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activator of LCAT
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how is apo A distributed?
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HDL
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what si the function of apo-B-100?
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ligand for receptor; structural role
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how is apo B-100 distributed?
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VLDL, LDL
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what is the function of apo B-48?
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structural role
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how is apo B-48 distributed?
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chylomicrons
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what is the function of apo C-II?
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activator of lipoprotein lipase
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how is apo C-II distributed?
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chylomicron, VLDL, HDL
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what is the purpose of apo E?
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ligand for receptor
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how is apo E distributed?
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chylomicron, VLDL, apo E-rich HDL
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what is the site of action of LCAT?
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lipoproteins, especially nascent HDL
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what are the substrates of LCAT?
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phosphatidylcholine and cholesterol
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what is the site of action of LPL?
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capillary surfaces
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what are the substrates of LPL?
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triacylglycerol in VLDL and chylomicron
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what is the site of action of hepatic lipase (HL)?
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liver sinusoids
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what are the substrates of HL?
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triacylglycerol and phospholipids in IDL and HDL
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what is the site of action of acid lipase?
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lysosomes
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what are the substrates of acid lipase?
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triacylglycerol and cholesterol esters
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what is the role of liver for glucose?
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supplies glucose to other systems
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how does the liver regulate blood glucose?
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by conversion to and from glycogen
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what can the liver produce glucose from?
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lactate from overused muscles
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what happens in the liver if there is an excess of glucose and glycogen?
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fatty acid synthesis
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what does the liver make for use by other organs?
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ketone bodies
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what happens in the liver after a meal?
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glucse from the blood enters the liver.
G6P is used as fuel glycogen is converted to fatty acid VLDL sends fatty acids to adipose tissue |
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what happens in the liver after fasting?
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fatty acids sent from adipose to liver
converted to glycogen, G6P, then glucose glucose is sent to the blood |
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how are fatty acids transported from the liver to adipose tissue?
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VLDL complexes
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how are fatty acids stored in adipose cells?
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converted to triglycerides
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what glucose product is required to make triglycerides?
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glycerol-3-phosphate
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how is energy supplied to muscle tissue at rest?
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beta oxidation of fatty acids
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how is energy supplied to muscle tissue at work?
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internal supply of glycogen.
lactate from glycolysis alanine from protein degradation |
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what organ accounts for 60% of all the glucose used by the body?
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the brain
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what happens if glucose drops in the brain?
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it will use ketone bodies
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why can't the brain use fatty acids for energy?
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fatty acids can't cross the blood-brain barrier
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after the stomach, where do fats go?
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small intestines
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where are bile salts, lecithin, and cholesterol before they enter teh small intestins?
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liver
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what happens to fats, bile salts, lecithin, and cholesterol in the small intestines?
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attached by pancreatic lipase
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what is pancreatic lipase?
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the enzyme used in the hydrolysis of fats
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what does pancreatic lipase produce?
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fatty acids and a monoglyceride
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what enzyme assists pancreatic lipase?
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collipase
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what is collipase?
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a protein that binds to the surface of the lipid droplet
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where does phospholipase A cleave?
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a the ester bond
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where does phospholipase C cleave
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phosphate off of carbon 3
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where does phospholipase D cleave?
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The group after the phosphate
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after hydrolysis, where do fatty acids and monoglycerides go?
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pass through the wall of the small intestines
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what happens after fatty acids and monoglycerides pass through the wall of the small intestines?
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reassemble into triglycerides
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what happens in lipid oxidation after fatty acids reassemble into triglycerides?
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a protein is added and chylomicrons are produced (B-48)
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what happens in lipid oxidation after chylomicrons are produced?
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chylomicrons are passed via the lymph system to the blood
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what are the major components of a chylomicron?
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apolipoprotein, triglyceride, cholesteryl ester, phospholipid
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as lipoproteins, w hat component increases?
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triacylglycerol
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where is the site of action of LCAT?
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lipoproteins, especially nascent HDL
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what is the substrate for LCAT?
|
phosphatidylcholine and cholesterol
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what is the site of action for LPL?
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capillary surfaces
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what is the substrate for LPL (lipoprotein lipase)
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triacylglycerol in VLDL and chylomicron
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what is the site of action of hepatic lipase (HL)?
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liver sinusoids
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what is the substrate of hepatic lipase?
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triacylglycerol and phospholipids in IDL and HDL
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what is the site of action of acid lipase?
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lysosomes
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what is the substrate of acid lipase?
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triacylglycerol and cholesteryl esters
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what is the function of Apo-A-I
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activator of LCAT
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where is apo A-I distributed?
|
HDL2, HDL3
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what is the function of apo A-II?
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structural role
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what ist he distribution of apo A II?
|
chylomicron
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what isthe function of apo B-100?
|
ligand for receptor; structural role
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what is the distribution of apo B-100?
|
VLDL, LDL
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what is the function of apo B-48
|
structural role
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what is the distribution of apo B-48?
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chylomicron
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what ist he function of apo C-II?
|
cofactor with lipoprotein lipase
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what is the distribution of apo C-II?
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chylomicron, VLDL, HDL2
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what is the function of apo E?
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ligand for receptor
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what is the distribution of apo E?
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chylomicron, VLDL, apo-E-rich HDL
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what are the two pathways that lead to VLDL, HDL, and IDL?
|
exogenous pathway where dietary cholesterol ends up in the liver via intestines
OR endogenous pathway where extrahepatic tissues send cholesterol to the liver |
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how are fatty acids stored an adipocyte?
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as triglycerides
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where are fatty acids stored in adipocytes?
|
cytoplasm
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what happens in adipose tissue during a "fed" stage?
|
glucose and VLDL from the liver enters adipose tissue
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what happens in adipose tissue during fasting?
|
triglycerides are converted to glycerol and fatty acids, then sent to the liver and albumin respectively
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how can glycerol from fat be made into an energy source?
|
glycerol converted to glycerol-3-phosphate in the liver
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what does glycerol have to be converted to from fat to enter glycolysis?
|
dihydroxyacetone phosphate (DHAP)
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how much glycogen does the body usually store?
|
a one day supply
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which has more energy per gram, fat or glycogen?
|
fat
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how much water is in glycogen?
|
70%
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how much fat is stored in the human body?
|
one month supply
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how much water is in fat?
|
none
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when is fat released?
|
after glycogen is gone
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what ist he major carrier of free fatty acids in blood?
|
plasma albumin
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how much can plasma albumin carry?
|
up to 10 mol/mol
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what are carriers of esterified fatty acids as triacylglycerols?
|
lipoproteins
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how many carbons are removed at each beta oxidation?
|
2
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what is the end product of beta oxidation of lipids?
|
1 acetyl CoA
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where does acetyl CoA go after beta oxidation?
|
citric acid cycle for energy production
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why is beta oxidation named so?
|
the beta carbon of the fatty acid is oxidized to a ketone.
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what is the activation step of beta oxidation?
|
conversion of the fatty acid into a fatty acyl CoA
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does the activation step require energy?
|
yes
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where does the fatty acid acyl go once it is fomed?
|
into the mitochondrira for further degradation.
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how many steps is the activation step?
|
2.
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how is a fatty acid converted to a fatty acyl-CoA?
|
with ATP and Coenzyme A catalyzed by acyl-CoA synthetase. linkage between fatty acid carboxyl group adn thiol group of coenzyme A yield a fatty acyl CoA
|
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where are fatty acids converted to fatty acyl- CoA?
|
outer mitochondrial membrane
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how many ATPs does it take to convert a fatty acyl-CoA back to a fatty acid?
|
2
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how is malonyl CoA made and for what purpose, and where?
|
acetyl CoA carboxylase makes it from acetyl Coa to make fatty acids.
|
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what is malonyl coa?
|
the first intermediate in fatty acid synthesis
|
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what does malonyl coa inhibit?
|
acyltrasferase I
|
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what ins important about the inhibition of acyltransferase I by malonyl Coa?
|
prevents the simultaneous synthesis and degradation of fatty acids
|
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|
fatty acids destined for mitochondrial oxidation are attached to what?
|
carnitine to form fatty acyl-carnitine in a transesterification catalyzed by carnitine acyltransferase I
|
|
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where are fatty acids attached to carnitine?
|
in the outer mitochondrial membrane.
|
|
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by what transporters does fatty acyl carnitine ester enter the matrix?
|
acyl-carnitine/carnitine transporter
|
|
|
which enzyme regenerates fatty acyl-CoA and releases it with free carnitine into the matrix?
|
carnitine acyl- transferase II in inner mitochondrial membrane.
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what are the major enzymes in beta oxidation?
|
dehydrogenase, hydrloase, dehydrogenase, thiolase, acetyl transferase
|
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where is acetyl coa further oxidized?
|
citric acid cycle
|
|
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what are the major steps in beta oxidation of a fatty acid?
|
oxidation, hydration, oxidation, thiolysis
|
|
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what are the start and end products of beta oxidation of a fatty acid?
|
acyl CoA to acetyl CoA
|
|
|
which yields mor eATP, saturated or unsaturated fatty acids?
|
saturated
|
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|
how is the oxidation of an unsaturated fatty acid different from an oxidated?
|
unsaturated requires more isomerization and reduction.
|
|
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how is lipase in adipose tissue activated?
|
by phosphorylation (glucagon).
|
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|
what is lipase activity like when insulin levels are high?
|
lipase levels are low
|
|
|
what inhibits carnitine acyltransferase I?
|
high levels of malonyl CoA, preventing beta oxidation during fattya cid synthesis
|
|
|
what must be available for beta oxidation to proceed?
|
CoA, since it is the substrate for the thiolase reaction
|
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what inhibits beta-hydroxylacyl CoA dehydrogenase?
|
NADH/NAD
|
|
|
what inhibits thiolase?
|
high aceytl CoA
|
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|
what is stearic acid?
|
an 18 carbon fatty acid
|
|
|
how many ATP are used at each step?
|
-2 for activation
12* 9 for 9 acetyl CoA 8*2 for 8 FADH2 8*3 for NADH = 146 |
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when are ketone bodies fromed?
|
if too much acetyl CoA is produced from Beta oxidation
|
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when would too much acetyl coa be formed in beta oxidation?
|
when fasting, starving, or a high fat diet
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what ist he first step in the citric acid cycle?
|
acetyl Coa + oxaloacetate --> citrate
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|
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what are 3 examples of ketone bodies?
|
D B-hydroxybutyrate, acetoacetate, acetone
|
|
|
what is ketosis?
|
abnormal rise in the concentration of ketone bodies in the blood
|
|
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what causes ketosis?
|
starvation, high fat, low carb diet, diabetes mellitus
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|
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what is ketoacidosis?
|
two of the ketone bodies are acids which causes lowering of hte blood pH
|
|
|
what is ketogenesis?
|
pathway for the production of ketone bodies
|
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how does ketogenesis occur?
|
enzyme mediated reaction taht starts with the reversal of the last step of beta oxidation.
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what ist he regulation point of ketogenesis?
|
HMG CoA synthase
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what is the first stage of ketogenesis?
|
condensation
|
|
|
what is acetone breath?
|
spontenous loos of CO2 from acetoacetate?
|
|
|
what is acetone breath a symptom of?
|
untreated diabetes mellitus or starvation conditions
|
|
|
what is acetone breath a conversion of?
|
decarboxylation of acetoacetate into acetone
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|
|
Where are acetoacetate and B-hydroxybutyrate produced?
|
primarliy in the liver
|
|
|
where to ketone bodies normally go?
|
muscles and brain for energy. other tissues may use them if glucose is low.
|
|
|
where is acetone eliminated?
|
urine or breath
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where does fatty acid oxidation take place?
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msucle, liver
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where does fatty acid synthesis take place?
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liver, adipose
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where in the cell does fatty acid oxidation tak eplace?
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mitochonrial matrix
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where in the cell does fatty acid synthesis tak eplace?
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cytosol
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what are the intermediates in oxidation?
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acetyl CoA
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what are the intermediates in synthesis?
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acetyl CoA, malonyl- CoA, NADPH
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what is the activator of synthesis?
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citrate
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what is the inhibitor of oxidation?
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malonyl CoA
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what is the inhibitor of synthesis?
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long-chain acyl CoA
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what is the energy state of oxidation?
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high ADP
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what is the energy state of synthesis?
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high ATP
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what is the metabolic state of oxidation?
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fasting, starvation
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what is the metabolic state in synthesis?
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carboyhydrate feeding
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what is the hormonal state of oxidation?
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insuline/glucagon decrease
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what is the hormonal state of synthesis?
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insulin/glucagon increase
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