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Biochem Lipids
Everything about lipds
| Question | Answer |
|---|---|
| What are anabolic steroids? | Hormones that increase muscle mass and performance |
| Why are saturated fats and cholesterol bad? | Strong correlation between these lipids and heart disease Large amounts of saturated fats linked to colon, esophageal, stomach, and breast cancers |
| What are lipids? | collection of organic molecules of varying chemical composition |
| Types of fatty acids? | Saturated and unsaturated |
| What are glycerides? | Glycerol containing lipids |
| What are nonglyceride lipids? | Sphingolipids, steroids, waxes |
| What are lipoproteins? | complex lipids |
| Functions of lipids? | Excellent energy source energy storage cell membrane structural components hormones vitamins vitamin absorption protection insulation |
| Energy given off by 1 gram of lipid? | 9 kcal |
| Lipids primarily stored as...? | Triglycerides |
| What membrane structural components do lipids form? | phosphogycerides sphingolipids steroids |
| Importance of hormones | Critical chemical messengers that allow tissues of body to communicate |
| Lipid soluble vitamins? | ADEK and used for blood clotting and vision |
| How do lipids help transport vitamins? | Carrier for lipid soluble vitamins Transported into small intestine |
| How does lipid protect the body? | Shock absorber, 4% of total body fat reserved for this purpose |
| What are fatty acids? | long-chain monocarboxylic acids |
| Due to biosynthesis, fatty acids usually contain... | even number of carbons |
| What happens to melting point with increasing carbon number in saturated fats? | Increases |
| Fatty acids with how many carbons are solid at room temp? | 10+ |
| Melting pt of saturated fatty acid is.... that of an unsaturated fatty acid of same chain length | Greater |
| Difference between saturated and unsaturated fats? | Unsaturated fats have double carbon bonds |
| What configuration are double bonds in (unsaturated fats)? | cis |
| What dictates placement and geometric configuration of unsaturated fatty acids | enzymes that catalyze the biosynthesis |
| What degree is the bend in a cis double bond? | 30 |
| Melting point ..... of unsaturated fatty acids with increasing hydrocarbon chain length | increases |
| Chemical reactions involving fatty acids | esterification, saponification, addition of double bond, partial hydrogenation |
| What essential fatty acids cannot be synthesized by the body? | linolenic and linoleic |
| Why us linoleic acid essential? | synthesis of arachidonic acid precursor of eicosanoids |
| What are eicosanoids? | Derivatives of 20 carbon fatty acids |
| What are prostaglandins? | Extremely potent biological molecules with hormonlike activity, unsaturated carboxylic acids, have 5 carbon ring, made in most tissues |
| What does aspirin do? | inhibits cyclooxygenase which is needed for arachidonic acid to PGH2 conversion |
| Why does aspirin work in many different targets? | reaction catalyzed by cyclooxygenase occurs in all cells |
| Biological processes regulated by eicosinoids | blood clotting inflammatory response reproductive system gastrointestinal tract kidneys respiratory tract |
| What are omega 3 fatty acids and where are they found? | EPA, DHA, found in fish alpha linoleic acid found in flax seed |
| Why are omega 3s important? | reduce risk of cardiovascular disease by decreasing blood clot formation, triglyceride levels, and atherosclerotic plaque growth |
| What is EPA a precursor for? | prostacyclin inhibits clumping of platelets and reduces clot formation |
| Where is DHA useful? | sperm, brain, retina, reduces triglyceride levels |
| What are the omega 6 acids? | Linoleic, arachidonic |
| What do omega 3s do? | prostaglandin precursor for anti-inflammatory response |
| What do omega 6s do? | prostaglandin precursor for inflammatory response |
| What are neutral glycerides? | lipid esters that contain glycerol molecule and fatty acids, non-ionic, nonpolar |
| How are neutral glycerides produced? | esterification of glycerol with fatty acid |
| Why are triglycerides important? | Storage of energy, uncharged |
| What is the majority of fat cells in the body? | neutral triglycerides |
| An important phosphoglyceride and its role in the body? | lecithin component of cell membranes found in egg yolks, soybeans |
| What are sphingomyelins and why are they important? | nonglyceride lipid, sphingolipid, structural lipid component of nerve cell membranes, myelin sheath |
| Important glycolipids? | cerebrosides found in membranes of brain cells |
| Examples of steroids? | bile salts, testosterone, estrone |
| Role of cholesterol? | regulation of fluidity of membrane as a result of nonpolar fused ring, narrowing of arteries due to plaques |
| What are bile salts? | emulsifying agents whose polar hydroxyl groups interact with water, synthesized in liver and stored in gallbladder |
| What can cholesterol be converted to? | Progesterone |
| What is cortisone responsible for? | metabolism of carbs |
| Where is aldosterone produced and what is its job? | adrenal cortex, activated when blood Na level too low, causes Na ions and water to be returned to blood |
| Name an important wax | lanolin found as protective coating for hair and skin and is used in skin creams and ointments |
| Whar are the four classes of plasma lipoproteins? | chylomicrons, very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) |
| Triglycerides are assembled into these for transport | VLDL |
| Cholesterol is packaged in this for transport | LDL |
| What determines membrane fluidity? | proportion of saturated to unsaturated fatty acids |
| Pathway used under aerobic conditions for fatty acid metabolism | pyruvate to acetyl CoA to citric acid cycle |
| Why is acetyl CoA important? | starting material for biosyntheis of fatty acids, cholesterol, steroid hormones |
| Where are dietary lipids processed in animals? | Small intestine |
| How are lipids stored in heart and other cells? | fat droplets surrounded by mitochondria |
| How are fatty acids degraded? | removal of 2 carbon acetate groups from carboxyl end of fatty acid |
| Name for fatty acid degradation? | beta oxidation |
| Number of ATP produced from FADH2 and NADH | 2, 3 |
| What is needed for acetyl CoA to enter citric acid cycle? | Oxaloacetate |
| How is oxaloacetate made? | Conversion of pyruvate |
| What must be true for acetyl CoA not to turn into ketone bodies? | Glycolysis rate must be the same as beta oxidation |
| Causes of ketosis | starvation (low carb), uncontrolled diatetes mellitus |
| How are ketones generated? | reversal of last step of beta oxidation, enzyme catalyzes fusion of 2 acetyl CoA molecules to end up at HMG-CoA |
| What is the primary reaction in mitochondrial matrix for ketogenesis? | acetoacetate + NADH -> beta-hydroxybutyrate |
| What organ uses ketone bodies are primary source of energy? | Heart |
| Organ that uses ketone bodies as secondary source after glucose? | Brain |
| Intracellular location of fatty acid biosynthesis? | cytoplasm |
| Intracellular location of fatty acid degradation? | mitochondria |
| In beta oxidation, this is a carrier for fatty acids? | ACP |
| How many enzymes involved in biosynthesis and degradation of fatty acids? | complex (fatty acid synthase), and none |
| Electron carriers produced by degradation versus synthesis of fatty acids? | NADH/FADH2 and NADPH |
| Pathway used by liver in response to insulin | insulin -> blood glucose taken by liver --> stored as glycogen |
| Pathway used by liver in response to glucagon | glucagon --> breakdown of glycogen --> release glucose to blood |
| What is used under anaerobic conditions by the liver to make glucose? | lactate |
| What happens in the liver when excess fuel or energy is available | synthesis of fatty acids -> make triglycerides -> transported to adipose tissues by VLDL |
| What happens in starvation? | fatty acids converted to acetoacetate and other ketone bodies |
| What effects does insulin have of cellular metabolism? | stimulates glycogen synthesis, inhibits glycogenolysis and gluconeogenesis, stimulates transport and uptake of amino acids, incorporation of amino acids into proteins, uptake of glucose by adipose cells, synthesis and storage of triglycerides |
| What does glucagon do? | responds to decreased glucose, inhibits glycogen synthesis, stimulates glycogenolysis and gluconeogenesis, breakdown of fat and ketogenesis |
| During fasting what is the role of glucagon? | production of glucagon -. increase blood glucose through breakdown of glycogen and production of glucose by gluconeogenesis |
| 17.19 In terms of solubility, explain why diet that contains no lipids can lead to a deficiency of the lipid soluble vitamins? | Lipid soluble vitamins are transported into cells of the small intestine in association with dietary fat molecules. Thus a diet low in fat reduces the amount of vitamins ADEK that enters the body |
| 17.25 Explain relationship between fatty acid chain length and melting point. | Melting points of fatty acids increase as length of the hydrocarbon chains increase. This is due to intermolecular attractive forces, including van der Waals, increase as the length of the hydrocarbon chain increases |
| 17.43 What is the function of essential fatty acids? | The essential fatty acid linoleic acid is required for the synthesis of arachidonic acid, a precursor for the synthesis of the prostaglandins |
| 17.45 What is the biochemical basis for the effectiveness of aspirin in decreasing the inflammatory response? | Aspirin effectively decreases the inflammatory response by inhibiting the synthesis of all prostaglandins. Works by inhibiting cyclooxygenase, the first enzyme in prostaglandin biosynthesis. The inhibition results from the transfer of an acetyl group |
| 17.47 List four effects of prostaglandins | Smooth muscle contraction, enhancement of fever and swelling associate with the inflammatory response, bronchial dilation, inhibition of secretion of acid into the stomach |
| 17.49 What do the terms omega 3 and omega 6 indicate about structures of the fatty acids in those classifications? | position of the double bond nearest the terminal methyl group |
| 17.51 Summarize the health benefits associated with omega 3 fatty acids | Omega 3 fatty acids reduce risk of cardiovascular disease by decreasing blood clot formation, blood tryglyceride levels, and growth of atherosclerotic plaque |
| 17.53 Explain relationship between increased levels omega 3 fatty acids and a decreased risk of cardiovascular disease | Decrease in blood clot formation, along with reduced blood triglyceride levels result in improved arterial health. This results in lower bp, and decreased risk of sudden death and heart arrhythmias |
| 17.55 Explain logic behind decreasing ratio of omega 6 to omega 3 fatty acids int the diet | omega 3s are precursors to anti-inflammatory prostaglandins while omega 6s are opposite. |
| 17.61 What do you predict the physical state would be of a triglyceride with 3 saturated fatty acid tails? | A triglyceride with three saturated fatty acid tails would be a solid at room temperature. The long, straight fatty acid tails would stack with one another because of strong intermolecular and intramolecular attractions |
| 17.67 What are the structural differences between triglycerides and phospholipids? | Triglycerides consist of three fatty acids esterified to the three hydroxyl groups of glycerol. Phospholipids there are only two fatty acids esterified to glycerol |
| 17.73 What is the biological function of sphingomyelin? | Sphingomyelins are important structural lipid components of nerve cell membranes. They are found in the myelin sheath that surrounds and insulates cells of the CNS |
| 17.75 What is the role of cholesterol in biological membranes? | Cholesterol is readily soluble in the hydrophobic region of biological membranes. It is involved in regulating the fluidity of the membrane |
| 17.77 What are the biological functions of progesterone, testosterone, and estrone? | Progesterone is the most important hormone associated with pregnancy. Testosterone is needed for development of male characteristics. Estone is required for proper female development. |
| 17.79 What is the medical application of cortisone? | Cortisone is used to treat rhematoid artheritis, asthma, gastrointestinal disorders, and many skin conditions |
| 17.81 A wax found in beeswax is myricyl palmitate. What fatty acid and what alcohol are used to form this compound? | Myricyl palmitate (beeswax) is made up of the fatty acid palmitic acid and the alcohol myricyl alcohol |
| 17.83 What are isoprenoids? | Large, diverse collection of lipids that are synthesized from the isoprene unit |
| 17.85 List some important biological molecules that are terpenes | Steroids and bile salts, lipid soluble vitamins, certain plant hormones, chlorophyll |
| 17.89 There is a single, unique structure for the cholesterol molecule. What is meant by the terms good and bad cholesterol? | HDL is considered good, because a correlation has been made between elevated levels of HDL and a reduced incidence of atherosclerosis. LDL is bad cholesterol |
| 17.91 What is the relationship between atherosclerosis and high blood pressure? | Results when cholesterol and other substances coast the arteries causing a narrowing of the passageways. |
| 17.93 How does a genetic defect in the LDL receptor contribute to atherosclerosis? | If LDL receptor is defective, it cannot function to remove cholesterol-bearing LDL particles from the blood. |
| 17.99 What is the major effect of cholesterol on the properties of biological membranes? | Cholesterol is freely soluble in the hydrophobic layer of the membrane. It moderates fluidity by disrupting the stacking of the fatty acid tails of membrane phospholipids |
| 17.101 What experimental observation shows that proteins diffuse within the lipid bilayers of biological membranes? | labelling with fluorescent dyes first localized, then spread across fused mouse-human cell membrane. |
| 17.103 How will the properties of a biological membrane change if the fatty acid tails of the phospholipids are converted from saturated to unsaturated chains? | If the fatty acyl tails of phospholipids are converted from saturated to unsaturated, the fluidity of the membrane will increase. |
| 23.19 What is the major storage form of fatty acids? | Triglycerides |
| 23.21 What is the outstanding structural feature of an adipocyte? | Large fat globule that takes up nearly the entire cytoplasm |
| 23.23 What is the general reaction catalyzed by lipases? | Lipases catalyze the hydrolysis of the ester bonds of triglycerides |
| 23.25 List three major biological molecules for which acetyl CoA is a precursor. | Acetyl CoA is the precursor for fatty acids, several amino acids, cholesterol, and other steroids |
| 23.27 What is the function of chylomicrons? | Plasma lipoproteins (proteins and triglycerides aggregrate) that carry dietary triglycerides from the intestine to all tissues via bloodstream |
| 23.29 What is the function of bile salts in the digestion of dietary lipids? | Detergents. Fat globules stimulate their release from gallbladder. Emulsify the lipids, increasing their surface area and making them more accessible to digestive enzymes (pancreatic lipases) |
| 23.31 Describe the stages of lipid digestion. | When fat globules reach the duodenum, emulsified by bile salts. Triglycerides in the resulting tiny fat droplets are hydrolyzed into the monoglycerides and fatty acids by action of pancreatic lipases, assisted by colipase. Absorbed by intestinal lining. |
| 23.41 What products are formed when the omega-phenyl-labeled carboxylic acid 14-phenyltetradecanoic acid is degraded by beta oxidation? | 6 acetyl CoA, 1 phenyl acetate, 6 NADH, 6 FADH2 |
| 23.43 Calculate the number of ATP molecules produced by complex beta oxidation of the 14 carbon saturated fatty acid, tetradecanoic acid, aka myristic acid? | 112 ATP |
| 23.45 Calculate the number of ATP molecules produced by complete beta-oxidation of lauric acid | 95 ATP |
| 23.47 What is the fate of the acetyl CoA produced by beta oxidation? | Acetyl CoA produced by beta oxidation enters the citric acid cycle |
| 23.57 Why do uncontrolled diabetics produce large amounts of ketone bodies? | Glucose in blood cannot get into cells of the body. Excess is excreted in the urine. Body cells degrade fatty acids because glucose not available. Beta oxidation releases large quantities of acetyl CoA excess of which is used for ketogenesis. |
| 23.59 When does the heart use ketone bodies? | preferred energy source |
| 23.65a What is the role of the phosphopantetheine group in fatty acid biosynthesis? | Allows formation of a high energy thioester bond with a fatty acid |
| 23.65b From what molecule is phosphopantehteine made? | Derived from vitamin pantothenic acid |
| 23.67 How does the structure of fatty acid synthase differ from that of enzymes that carry out beta oxidation? | Fatty acid synthase is a multienzyme complex consisting of 7 enzymes involved in fatty acid synthesis. Found in cell cytoplasm. In beta ox, no enzymes are associated together. Free in the mitochondrial matrix space. |
| 23.73 Which pathway provides the majority of the ATP for resting muscle? | Beta oxidation of fatty acids |
| 23.75 What is the major metabolic function of the liver? | Regulate blood glucose levels |
| 23.77 What are the major fuels of the heart, brain, and liver? | Ketone bodies for the heart; Glucose for the brain; Amino acid caron skeletons for the liver |
| 23.79 Describe triglyceride metabolism in an adipocyte. | FAs absorbed by adipocytes. Glycerol-3-phosphate used to make triglycerides which are constantly hydrolyzed and resynthesized in adipocytes. Rates of hydrolysis and synthesis are determined by lipases that are under hormonal control. |
| 23.81 In general, what is the effect of insulin on catabolic and anabolic or biosynthetic processes? | Stimulates anabolic processes including glycogen synthesis, uptake of amino acids and protein synthesis, and triglyceride synthesis. Catabolic processes (glycogenolysis) inhibited. |
| 23.85 What is the trigger that causes glucagon to be secreted into the bloodstream? | Decrease blood sugar levels trigger secretion of glucagon into bloodstream. |
| 23.87 Where is insulin produced? | Produced by beta cells of islets of Langerhans in the pancreas |
| 23.89 How does insulin affect carb metabolism? | Stimulates uptake of glucose from blood into cells. Enhances glucose storage by stimulating glycogenesis and inhibiting glycogen degradation and gluconeogenesis. |
| 23.91 How does insulin affect lipid metabolism? | Stimulates synthesis and storage of triglycerides |
| 23.93 Explain the importance of the antagonistic effects of insulin and glucagon | Insulin secreted when blood glucose high. Facilitates uptake and storage of glucose by target cells. Glucagon is secreted when blood glucose low. Stimulates release of glucose into blood to restore normal levels. |
| What happens to carbons 1,2,and 3 in a triglyceride? | Saturated, unsaturated, saturated or unsaturated |
| Which molecule is more efficient at energy storage and by how much? | Fat and 6 times |
| What is the respiratory quotient? | Used to determine which fuel is being utlized |
| What do most glycolipids contain in their long chain? | amino alcohol, sphingosine |
| What enzyme is used to cleave the fatty acid to produce fatty acyl-CoA? | thiokinase found in cytosol |
| What transfers fatty acyl-CoA to mitochondria during fatty acid metabolism? | carnitine |
| What enzyme is used to remove a hydrogen from fatty acid acyl-CoA after it's been alpha-beta unsaturated? | enoyl-CoA dehydrogenase |
| What enzyme is used to remove the hydrogen from the beta position on the fatty acid? | Beta-hydroxyl-CoA dehydrogenase |
| What enzyme is used to go from beta-keto-acyl-CoA to acetyl-CoA leading to Krebs cycle? | beta-ketothiolase |
| What does carnitine palmytoyl-transferase do? | transfers long chain fatty acids such as palmitate or myristate from carnitine to acyl-CoA |
| Where are very long chain fatty acids degraded? | peroxisomes |
| What are the products of beta oxidation of fatty acids? | 2-carbon acetyl groups (acetyl-CoA) |
| What decarboxylates pyruvate in mitochondria? | pyruvate dehydrogenase |
| What enzyme catalyzes the synthesis of fatty acids? | acetyl-CoA carboxylase, a rate limiting enzyme |
| How many catalytic sites does fatty acid synthase have? | 7 used for converting malonyl groups to fatty acid |
| What energy molecule is used to activate lipid precursors? | CTP, cytidine triphosphate |
| What does epinephrine/adrenaline do? | fight or flight |
| Exported triglycerides are broken down into fatty acids at capillary walls by? | lipoprotein lipase/capillary lipase |
| Is conversion of carbohydrate to fat reversible? | No |
| What directs circulating lipoproteins to their destinations? | apolipoproteins |
| Where is most circulating cholesterol found? | LDL |
| What do lipases do? | hydrolyze ester bonds of triglycerides and phospholipids |
| What acts on chylomicrons in the capillaries? | lipoprotein lipase |
| Triglycerides in adipocytes are hydrolyzed by what? | hormone-sensitive lipase |
| cAMP stimulates a kinase which phosphorylates and activates what enzyme? | hormone-sensitive enzyme |
| What does protein kinase do? | phosphorylates cAMP to ATP |
| What enzyme cleaves HMG-CoA to mevalonate in cholesterol synthesis? | reductase, the rate determining enzyme |
| Phosphoinositides are hydrolyzed by what enzyme? | phospholipase C |
| What enzyme is used for phospholipid in cell membrane to arachidonic acid? | phospholipase A2 |
| What enzyme is targeted by aspirin and what does it do? | cyclooxygenase 1 and 2, make prostaglandins and thromboxanes |
| What enzyme is used in formation of leukotrienes? | lipoxygenase |
| At what pH are all fatty acids ionized? what pKa? | physiological, less than 5 |
| Palmitic acid number of carbons, double bonds? | 16,0 |
| Stearic acid number of carbons, double bonds? | 18,0 |
| Linoleic acid number of carbons, double bonds? | 18,2 |
| Linolenic acid number of carbons, double bonds? | 18,3 |
| Arachidonic acid number of carbons, double bonds? | 20,4 |
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ilk0710
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