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369 Cards in this Set
- Front
- Back
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Roles of fatty acids
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1. Building blocks of phospholipids and glycolipids
2. Added onto proteins to create lipoproteins, which target them to membranes 3. Fuel molecules-source of ATP 4. Fatty acid derivatives serve as hormones and intracellular messengers |
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Fatty acids and triacylglycerols store...
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a lot of energy in a small volume; denser than carbohydrates because fats can be packed tightly without intervening water
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38kJ/g
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fat storage
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16kJ/g
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carbohydrate storage
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Why can fats store more than carbohydrates?
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Fats are more reduced and require less water for packing
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TAGs are synthesized in the...
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liver
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TAGs are stored in...
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adipose cells
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Why is lipid transport a problem?
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Fats are not soluble in water because they are too hydrophobic
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Bile is used to...
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break down insoluble fat globules
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Fats are metabolized mostly in...
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skeletal muscles, heart, and liver
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Bile is stored in the...
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gall bladder
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Bile enters the GI tract at...
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the start of the intestines
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Digestion of fats occurs primarily in the...
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small intestine
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fat particles are coated with...
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bile salts from the gall bladder
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Fats are degraded by...
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pancreatic lipase
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Bile is composed of...
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micelles of lecithin, cholesterol, protein, bile salts, inorganic ions and pigments
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Smaller fat globules leads to...
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larger surface area for attack by lipases
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Pancreatic lipase hydrolyzes...
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C1 and C3 to 2 fatty acids and 2-monoacylglycerides
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Once fats are broken down, they can be...
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absorbed by intestinal epithelial cells and bile salts are recirculated
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In the cells, fatty acids are converted by...
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fatty acyl CoA molecules
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Phospholipids are hydrolyzed by...
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pancreatic phospholipases
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The primary pancreatic phospholipase is...
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phospholipase A2
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Cholesterol esters are hydrolyzed by....
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esterases
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Cholesterol esters are hydrolyzed by esterases to form...
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free cholesterol, which is solubulized by bile salts and absorbed by the cells
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Lipids are transported throughout the body as...
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lipoproteins
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Lipoproteins consist of...
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a lipid core with amphipathic molecules forming layer on outside
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Acetyl CoA can be changed into...
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trigylcerides when more than needed for TCA cycle
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Chylomicrons transport fats....
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to the liver
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Fats are transported from the liver to other tissues by...
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VLDL, which is converted to LDL
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Fats are transported from tissues to the liver by...
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HDL
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HDL can get rid of...
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LDL
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LDL sticks to...
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fat and causes plaques
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Lipases cleave TAGs into...
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fatty acids and monoacylglycerol
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TAGs are converted into fatty acids by using...
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3 H20
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Chylomicrons contain....
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dietary triacylglycerols
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Chylomicron remnants contain...
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dietary cholesterol esters
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VLDLs transport...
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endogenous TAGs, which are hydrolyzed by lipoprotein lipase at capillary surface
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IDLs contain...
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endogenous cholesterol esters, which are taken up by liver cells via receptor-mediated endocytosis and converted to LDLs
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LDLs contain...
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endogenous cholesterol esters, which are taken up by liver cells via receptor-mediated endocytosis and are major carriers of cholesterol in the blood
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HDLs contain...
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endogenous cholesterol esters released from dying cells and membranes undergoing turnover
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Lipoprotein particles include...
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chylomicrons, VLDL, HDL, and LDL
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All of the lipoprotein particles contain...
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cholesterol
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High HDL cholesterol is considered...
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protective again heart disease
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Do TAGs enter cells easily?
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No, must be broken down into fatty acids and glycerol
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Once fatty acids and glycerols enter the cells of the small intestine...
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they are reassembled into TAGs, proteins are added, chylomicrons are produced, and they are sent to the blood via lymph
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1-2% proteins
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chylomicrons
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<0.95g/mL
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chylomicrons
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85-96% TAGs
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chylomicrons
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Fatty acid activation is...
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2 steps
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The enzyme used in fatty acid activation is...
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acyl CoA synthase
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Acyl CoA synthase is found in...
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the outer membrane of the mitochondria
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How many types of fatty acyl synthetases are there?
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3-one for long chain, one for medium chain, and one for short chain
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Fatty acid activation uses...
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ATP
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Fatty acid activation yields...
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AMP
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It costs ____ to convert AMP back to ATP
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2 ATP
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Fatty acid activation means...
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linking the fatty acid to CoA to form acyl-CoA
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Lipids can be used to make ATP through...
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beta oxidation
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Beta oxidation occurs in the...
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mitochondrial matrix
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How are lipids moved into the matrix?
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carnitine transporter
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Carnitine binds with acyl-CoA to become...
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acyl-carnitine
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Once inside the mitochondrial matrix, acyl-carnitine...
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binds with HSCoA to release acyl-CoA and regnerate carnitine
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The beta-oxidation reaction occurs at the...
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beta carbon
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Beta-oxidation is...
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four steps
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Beta-oxidation breaks down acyl-CoA...
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2 carbons at a time
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Beta-oxidation produces...
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acyl-CoA (shorter by two carbons), reduced QH2/NADH, a molecule of acetyl-CoA
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The three stages of beta-oxidation are...
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1. Activation of fatty acids in cytosol catalyzed by acyl-CoA synthetase; two high energy bonds are broken to produce AMP
2. Transport of fatty acyl CoA into mitochondria via carnitine shuttle 3. Beta-oxidation cyclic pathway in which many of the same enzymes are used repeatedly |
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The steps of beta-oxidation are:
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1. oxidation
2. hydration 3. oxidation 4. thialysis |
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In step one of beta-oxidation...
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oxidation occurs through acyl-CoA dehydrogenase
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In step two of beta-oxidation...
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hydration occurs through enoyl-CoA hydratase
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In step three of beta-oxidation...
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oxidation occurs through 3-hydroxyacyl-CoA dehydrogenase
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In step four of beta-oxidation...
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thialysis occurs through thiolase
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In step one of beta-oxidation, ____ goes in and ____ comes out, and ____ is reduced to _____
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FAD; FADH2; Q; QH2
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In step two of beta-oxidation, ____ goes in
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H20
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In step three of beta-oxidation, _____ goes in and ____ comes out
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NAD+; NADH + H
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In step four of beta oxidation, ___ goes in
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CoASH
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In step one of beta oxidation, ____ is converted to ______ by ________
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fatty acyl CoA; enoyl-CoA; acyl-CoA dehydrogenase
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In step two of beta oxidation, _____ is converted to ______ by ________
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enoyl-CoA; 3-hydroxyacyl-CoA; enoyl-CoA hydratase
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In step three of beta oxidation, _____ is converted to ______ by ________
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3-hydroxyacyl-CoA; ketoacyl-CoA; 3-hydroxyacyl-CoA dehydrogenase
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In step four of beta oxidation, _____ is converted to _______ and ______ by _______
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ketoacyl-CoA; fatty acyl CoA; acetyl-CoA; thiolase
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Is a lot of energy relased in oxidizing fatty acids?
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Yes
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How many ATP are produced from one round of beta-oxidation?
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2 from 1QH2; 3 from 1NADH; 12 from 1acetyl-CoA; 17 total
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One round of beta-oxidation produces 1QH2, which can be used to make...
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2 ATP
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One round of beta-oxidation produces 1NADH, which can be used to make...
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3 ATP
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One round of beta-oxidation produces 1 acetyl-CoA, which can be used...
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as 3NADH, 1QH2, and 1GTP in the citric acid cycle
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3NADH in the citric acid cycle can be used to make...
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9 ATP
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1QH2 in the citric acid cycle can be used to make...
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2 ATP and 1 acetyl-CoA
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1GTP in the citric acid cycle can be used to make...
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1 ATP
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ATP is produced through...
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oxidative phosphorylation
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To find out the amount of energy produced from a fatty acid...
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1. Count the total number of carbons
2. Substract two that will be left as acetyl-CoA 3. Multiple the amount of cycles by 17 ATP 4. Add 12 ATP for the acetyl-CoA that is produced by QH2 5. Subtract 2 ATP for the cost of activation |
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When a double bond appears in a fatty acid...
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two additional enzymes are needed to reduce the double bond
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The enzymes needed to reduce a double bond are...
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enoyl CoA isomerase and dienoyl CoA reductase
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If the double bond is at an odd number...
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2 ATP are used because you bypass the reductase step
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If the double bond is at an even number...
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3 ATP are used because reductase costs NADPH
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To find the total ATP produced when a fatty acid has a double bond...
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1. Count the number of carbons
2. Subtract 2 for the leftover 3. Multiply by 17 ATP 4. Add 12 ATP 5. Subtract 2 ATP for activation 6. Subtract either 2 or 3 ATP depending on location of double bond |
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When a fatty acid has an odd number of chains, you are left with...
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propionyl CoA
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Propionyl CoA is converted to...
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succinyl CoA, which then enters the Krebs cycle
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When dealing with odd numbered fatty acids, you need...
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adenosyl cobalamin cofactor for methylmalonyl mutase
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Instead of a total of 17 ATP being produced on the last cycle, with odd numbered fatty acids...
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only 8 are produced
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To find the total ATP produced of odd numbered fatty acids...
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1. Count the number of carbons
2. Subtract three that are leftover 3. Multiply by 17 ATP 4. Subtract 2 ATP 5. Add 8 ATP |
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Most fatty acid metabolism occurs in the...
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mitochondria
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The vitamin needed in breaking down fatty acids with odd numbers of carbons is...
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B12
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Some fatty acid metabolism occurs in special organelles called...
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peroxisomes
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Fatty acids that are longer than 22 carbons are oxidized in the...
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peroxisome
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Fat metabolism in peroxisomes generates...
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peroxide, which is quickly converted by catalase to H20
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In the peroxisome, electrons from beta oxidation are transferred to...
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oxygen, which forms hydrogen peroxide
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A disorder in which you cannot digest long or branched fatty acids is...
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Refsum's disease
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In Refsum's disease, excess _____ accumulates in cells and can cause....
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phytanate; neurological symptoms
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To find the total number of ATP produced for a long chain fatty acid...
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1. Count the number of cycles past C14
2. Multiply by 15 ATP 3. At C14, the mitochondria takes over, so multiply 6 cycles time 17 ATP 4. Add 12 ATP 5. Subtract 2 ATP |
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The reason only 15 ATP are produced in the peroxisome is...
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no QH2 is produced; H2O2 is produced instead
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Fatty acid synthesis occurs in the...
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cytosol
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Can organisms synthesize their own fatty acids?
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Yes by converting excess acetyl-CoA to fatty acid esters
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Synthesis of fatty acids occurs ______ carbons at a time
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2
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Acetyl group on acetyl CoA is moved from the mitochondria to the cytosol through...
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citrate transport system
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An acyl carrier protein is used during synthesis as...
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the point of attachment for the growing fatty acid
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Fatty acid synthesis occurs in a multienzyme complex known as...
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fatty acid synthase
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Fatty acid synthesis uses...
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NADPH
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Oxaloacetate in the mitochondria...
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is converted to citrate by citrate synthase
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Citrate in the mitochondria....
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is moved into the cytosol
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Citrate in the cytosol...
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is converted back to oxaloactate by ATP-citrate lyase
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In the citrate synthase reaction, _____ goes in and ____ comes out
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acetyl-CoA; HSCoA
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In the ATP-citrate lyase reaction, ____ goes in and _____ comes out
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ATP + HSCoA; ADP and acetyl-CoA
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The citrate transport system uses _____ and ______ to move ________ from the _______ to the ________
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oxaloacetate; citrate; acetyl-CoA; mitochondria; cytosol
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Intermediates of fatty acid synthesis are bound to...
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sulfhydryl groups of acyl carrier protein
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Intermediates of beta-oxidation are bound to...
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CoA
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Elongation of fatty acid stops when...
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palmitate (C16) is formed
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acetyl-CoA is converted to ____ for use in fatty acid synthesis
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malonyl-CoA
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Biotin + HCO3- + ATP --->
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Biotin-COO + ADP + Pi
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Biotin-COO + acetyl CoA --->
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malonyl-CoA + biotin
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The enzyme used in the conversion of acetyl CoA to malonyl-CoA is....
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acetyl-CoA carboxylase
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The COO- group on biotin is transferred to...
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acetyl-CoA to form malonyl-CoA
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Transacylase is used to....
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attach fatty acids to acyl carrier protein
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Fatty acid synthesis takes place in three stages:
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1. Mitochondrial acetyl-CoA is transported into cytosol via citrate transport system
2. Formation of malonyl CoA 3. ASsembly of fatty acid chain via fatty acid synthase |
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Formation of malonyl CoA is influenced by...
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glucagon which inactivates enzymes in the liver; epinephrine which inactivates enzyme in adipocytes; citrate which allosterically activates the enzyme; and fatty acyl-CoA which allosterically inhibits the enzyme
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The five stages of fatty acid assembly by fatty acid synthase are:
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1. Loading
2. Condensation 3. Reduction 4. Dehydration 5. Reduction |
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In the loading stage of fatty acid synthesis...
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acetyl CoA and malonyl CoA are attached to acyl carrier protein
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In the condensation stage of fatty acid synthesis...
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acetyl CoA and malonyl CoA are condensed by fatty acid synthase to form acetoacetyl-ACP
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In the first reduction stage of fatty acid synthesis...
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NADPH is oxidized to form hydroxybutyryl ACP
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In the dehydration stage of fatty acid synthesis...
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a double bond is formed
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In the second reduction stage of fatty acid synthesis...
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NADPH is a source of electrons and hydrogen to form butyryl-ACP
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Which steps of fatty acid synthesis are repeated?
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2-5, each time with malonyl-ACP to elongate the chain until palmitate is produced
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In the repeat steps, acetyl-ACP is replaced by...
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butyryl-ACP so that the acyl chain grows by 2 carbons
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Acetyl CoA + 7 malonyl CoA + 14 NADPH + 20H+ ---->
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palmitate + 7CO2 + 14NADP+ + 8HS-CoA + 6H2O
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Fatty acid metabolism is controlled by...
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acetyl-CoA carboxylase
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Fatty acid synthesis is stimulated by...
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abundant fuel (indicated by citrate)
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Prevention of simultaneous fatty acid oxidation and synthesis is controlled by...
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inhibition of carnitine shuttle by malonyl-CoA
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Fatty acid synthesis is maximal when...
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carbohydrate and energy are plentiful
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Important points of control in fatty acid synthesis are release of ______ from ______ and regulation of ________ in the ______
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1. fatty acids
2. adipocytes 3. carnitine acyltransferase I 4. liver |
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High insulin levels stimulate formation of....
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malonyl CoA which allosterically inhibits carnitine acyltransferase I; fatty acids remain in cytosol and are not transported to mitochondria for oxidation
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Insulin stimulate...
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fatty acid synthesis
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Insulin inhibits...
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hydrolysis of stored TAGs
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Glucagon and epinephrine inhibit...
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fatty acid synthesis
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When you eat excess foods...
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fat is synthesized and stored in adipocytes
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Fat release from adipocytes is regulated by...
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hormones, such as epinephrine during stress and glucagon during fasting
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Fatty acids are transported from the liver to adipose tissue as...
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VLDL complexes
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In the adipose tissue, fatty acids are converted into...
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TAGs for storage
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In adipose tissue, gglucose is converted into...
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glycerol-3-phosphate
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In adipose tissue, fatty acids are converted into...
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fatty acyl-CoA
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A water soluble molecule that is difficult for organisms to dissolve and transport
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cholesterol
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Cholesterol regulates...
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fluidity of cell membranes
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Cholesterol is a precursor for...
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steroid hormones, bile salts, and vitamin D
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Cholesterol biosynthesis consists of...
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30 different steps
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The first step of cholesterol biosynthesis starts with...
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3 molecules of acetyl CoA to form 3-hydroxy-3-methylglutaryl coA
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3-hydroxy-3-methyl-glutaryl-CoA is reduced to...
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mevalonate by HMG-CoA reductase
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HMG-CoA reductase is inhibited by...
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statins
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Statins can block...
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cholesterol synthesis to lower cholesterol in the blood
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Rate of HMG-CoA reductase synthesis is controlled by...
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sterol regulatory element which inhibits mRNA production
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Translation of HMG-CoA reductase mRNA is inhibited by...
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nonsterol metabolites derived from mevalonate
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Degradation of HMG-CoA reductase occurs at...
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high enzyme levels
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If HMG-CoA reductase is phosphorylated via glucagon pathway...
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there is decreased activity of cholesterol synthesis when ATP is low
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If HMG-CoA reductase is dephosphorylated via insulin pathway...
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there is increased activity of cholesterol synthesis
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Cells outside of the liver and intestine obtain cholesterol from the...
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blood
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Steps in uptake of cholesterol by LDL pathway:
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1. apolipoprotein on surface of LDL binds with receptor on membrane of cells
2. LDL-receptor complex internalized by endocytosis 3. vesicles formed fuse with lysosomes, which breaks apart protein part of lipoprotein to amino acids and hydrolyzes cholesterol esters 4. released unesterified cholesterol can be used for membrane biosytnhesis or be reesterified for storage |
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Defects in LDL receptor can lead to...
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familial hypercholesterolemia
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Cholesterol and LDL levels are elevated in...
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familial hypercholesterolemia
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Heterozygotes of familial hypercholesterolemia suffer from..
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atherosclerosis and increased stroke risk
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Homozygotes of familial hypercholesterolemia...
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usually die in childhood from coronary artery disease
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A competitive inhibitor of HMG-CoA reductase that blocks cholesterol synthesis
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lovastatin
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Inhibition of intestinal absorption of bile salts promotes...
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absorption of dietary cholesterol
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78% of air is...
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N2
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N2 is not very reactive because..
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the triple bond is very hard to break
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Useful nitrogen is found in...
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NH3, nucleotides, nucleic acids, NO3-, and NO2-
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N2 + 3H2 --->
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2NH3
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N2 + 3H2 ---> 2NH3 is favorable, but has high...
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activation energy
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Ammonia can be obtained from N2 by...
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Haber process
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In order to reduce nitrogen gas to ammonia, a process is used called..
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nitrogen fixation
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Higher organisms cannot form...
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NH4+
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Bacteria and blue-green algae possess...
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nitrogenase
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Nitrogenase has two subunits:
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1. strong reductase
2. two redox centers |
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Nitrogenase has an active site containing...
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iron-sulfur-molybdenum
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The strong reductase of nitrogenase has...
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iron-sulfur cluster that supplies electrons to the second subunit
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Iron and molybdenum reduce....
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N2 to NH4+
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The nitrogenase reaction is...
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ATP-dependent, but unstable in the presence of oxygen
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N2 + 8e- + 8H+ + 16ATP + 16H2O ---->
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2NH3 + H2 + 16 ADP+ 16Pi
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A symbiotic bacterium in the roots of legumes that has nitrogenase
|
Rhizobium
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Nodules are pink inside due to presence of...
|
leghemoglobin that binds to oxygen to keep the environment around the enzyme low in oxygen
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Plants and microorganisms can obtain NH3 by reducing...
|
nitrate and nitrite
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NO3-
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nitrate
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NO2-
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nitrite
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Nitrate and nitrite are used to make...
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amino acids, nucleotides, and phospholipids
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Organisms that are able to fix nitrogen
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diazotrophs
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N2 is converted to NH4+ by...
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nitrogenase
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The conversion of N2 to NH4+ is known as...
|
nitrogen fixation
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The conversion of NH4+ to NO2- and NO3- is known as...
|
nitrification
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The enzyme used in nitrification is...
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nitrite/nitrate reductase
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The conversion of NO3- to N2 is known as...
|
denitrification
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Once N2 has been reduced to ammonia...
|
it must be incorporated into metabolism fast because of its toxicity
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NH4+ is added to glutamate by...
|
glutamine synthetase
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NH4+ and glutamate form...
|
glutamine
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In bacteria, the conversion of ammonia and glutamate to glutamine is the...
|
initial entry of reduced nitrogen into metabolic pathways
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Nitrogen from ammonia can be effectively stored within...
|
glutamine
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Amino acids that are usually in higher concnetrations than other
|
glutamine and glutamate
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Glutamine is a...
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nitrogen carrier
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Alpha-ketoglutarate + glutamine --->
|
glutamate
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The enzyme used to convert alpha-ketoglutarate and glutamine into glutamate is...
|
glutamate synthase
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The alpha-amino group of most amino acids comes from...
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the alpha-amino group of glutamate by transamination
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Glutamine contributes its...
|
side chain nitrogen to some amino acids
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When ammonium ion is limiting...
|
most of glutamate is made by action of glutamine synthetase and glutamate synthetase
|
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Glutamate + NH4+ + ATP ---->
|
Glutamine + ADP + Pi + H+
|
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NH4+ + alpha-ketoglutarate + NADPH + ATP --->
|
glutamate + NADP+ + ADP + Pi
|
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The transfer of an amino group to an alpha-keto acid
|
transamination
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Key intermediate in amino acid metabolism
|
glutamate
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The enzyme used in transamination is....
|
transaminase
|
|
|
Glutamate + pyruvate --(transaminase)-->
|
alpha-ketoglutarate + alanine
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In a transaminase reaction, the amino group of the amino acid is transferred to the...
|
alpha-keto acid
|
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Pyruvate and oxaloacetate are...
|
alpha-keto acids
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Transaminase contain a...
|
pyridoxal cofactor called PLP
|
|
|
The precursor for pyridoxal cofactor is...
|
pyridoxine (B6)
|
|
|
3-phosphoglycerate can be combined with NAD+ to produce...
|
3-phospho-hydroxypyruvate and NADH
|
|
|
3-phosphohydroxypyruvate can be combined with glutamate to form...
|
3-phosphoserine and alpha-ketoglutarate
|
|
|
The phosphate group may be removed from 3-phosphoserine to form...
|
serine
|
|
|
Amino acids that must be supplied in the diet are...
|
essential
|
|
|
Amino acids that we can produce ourselves are...
|
nonessential
|
|
|
Carbon skeletons of amino acids come from...
|
intermediates of glycolysis, pentose phosphate pathway, or citric acid cycle
|
|
|
Amino acids derived from oxaloacetate include...
|
Asp, Asn, Met, Thr, Ile, Lys
|
|
|
Amino acids derived from pyruvate include...
|
Ala, Val, Leu
|
|
|
Amino acids derived from ribose-5-phosphate include....
|
His
|
|
|
Amino acids derived from PEP and erythrose-4-phosphate include...
|
Phe, Tyr, Trp
|
|
|
Amino acids derived from alpha-ketoglutarate include...
|
Glu, Gln, Pro, Arg
|
|
|
Amino acids derived from 3-phosphoglycerate include...
|
Ser, Cys, Gly
|
|
|
The nonessential amino acids are...
|
Ala, Asn, Asp, Cys, Glu, Gln, Gly, Ser, Thr
|
|
|
The essential amino acids are...
|
Val, Met, His, Leu, Phe, Lys, Iso, Thr, Trp, Arg
|
|
|
The saying to remember the essential amino acids is...
|
Very Many Hairy Little Pigs Live In The Torrid Argentine
|
|
|
Only human babies require...
|
arginine and histidine
|
|
|
Aspartate + Glutamine + ATP--->
|
asparagine + glutamate + AMP + PPi
|
|
|
Asparate can be converted to asparagine through...
|
asparagine synthetase
|
|
|
Synthesis of glycine, methionine, and TMP nucleotide requires...
|
tetrahydrofolate from folic acid
|
|
|
The only carrier of one-carbon groups is...
|
tetrahydrofolate
|
|
|
Folic acid deficiency is associated with...
|
spina bifida
|
|
|
Folic acid is found in...
|
grains, cereals, bread, pasta, flour
|
|
|
Serine + tetrahydrofolate --(serine hydroxymethyltransferase)-->
|
glycine + methylene-tetrahydrofolate
|
|
|
In the serine to glycine conversion, the R group of serine is transferred to...
|
THF, leaving an H as the side chain
|
|
|
Methionine can be produced from...
|
homocysteine and methyl-tetrahydrofolate
|
|
|
Homocysteine difffers from cysteine in that...
|
it has an extra CH2 group before the SH
|
|
|
In the production of methionine, a methyl group is transferred from _________ to _________, leaving ________ and ___________
|
1. methyl-tetrahydrofolate
2. homocysteine 3. tetrahydrofolate 4. methionine |
|
|
dUMP + N5-N10-methylene-tetrahydrofolate ---(thimidylate synthase)-->
|
dTMP + dihydrofolate
|
|
|
In the synthesis of TMP from UMP, the _____ on ______ is transferred from the _________
|
1. methyl
2. thymidine 3. methyltetrahydrofolate |
|
|
The enzyme used in the conversion of dUMP to dTMP is...
|
thymidylate synthase
|
|
|
Folate is important in...
|
rapidly dividing cells because it is needed to make dTMP
|
|
|
Some anti-cancer drugs inhibit...
|
enzymes that use folate
|
|
|
Methotrexate is structurally similar to...
|
folate, and inhibits dihydrofolate reductase
|
|
|
Catecholamines include...
|
dopamine, norepinephrine, epinephrine
|
|
|
Catecholemines are synthesized from...
|
tyrosine
|
|
|
Amino acids can serve as precursors for...
|
neurotransmitters
|
|
|
Parkinson's disease is due to a deficiency in...
|
dopamine
|
|
|
Depression is a result of deficiency in...
|
serotonin
|
|
|
Nucleotides in the cell can be used for...
|
1. activated precursors of DNA and RNA
2. nucleotide derivatives are activated intermediates in many biosynthetic pathways 3. universal currency of the cell (ATP) 4. components of major coenzymes NAD+, FAD, CoA 5. metabolic regulators (cyclic AMP) |
|
|
Nucleotide synthesis can be either...
|
de novo or by recycling bases
|
|
|
Tryptophan can be used to form..
|
serotonin
|
|
|
Serotonin can be used to form....
|
melatonin
|
|
|
Arginine is involved in...
|
free radical gas causing no vasodilation
|
|
|
Nucleotides are composed of...
|
1. nitrogenous base
2. pentose sugar 3. phosphate group |
|
|
Pyrimidines include...
|
cytosine, uracil, and thymine
|
|
|
Purines include...
|
adenine and guanine
|
|
|
Pentose sugar can be...
|
ribose or deoxyribose
|
|
|
A purine or pyrimidine base linked to a pentose sugar is...
|
nucleoside
|
|
|
Purines are...
|
double rings
|
|
|
Pyrimidines are...
|
single rings
|
|
|
Purine biosynthesis begins with...
|
ribose-5-phosphate from the pentose phosphate pathway
|
|
|
Ribose-5-phosphate comes from ________ which comes from _________ which comes from ________
|
ribulose-5-phosphate; 6-phosphogluconate; glucose-6-phosphate
|
|
|
Purine rings are synthesized de novo from five different precursors:
|
1. aspartate (N1 atom)
2. CO2 (C6 atom) 3. glycine (C4, C5, N7 atoms) 4. tetrahydrofolate (C2, C8) 5. glutamine (N3, N9) |
|
|
Ribose-5-phosphate and ATP form...
|
5-phosphoribosylpyrophosphate using ribose phosphate pyrophosphokinase
|
|
|
5-phosphoribosylpyrophosphate goes through 10 steps to become...
|
inosine monophosphate (IMP)
|
|
|
IMP can be converted into...
|
AMP or GMP
|
|
|
For AMP synthesis from IMP...
|
aspartate amino group condenses with keto-group of IMP (GTP dependent)
|
|
|
For GMP synthesis from IMP...
|
C-2 is oxidized to form xanthosine monophosphate; amide nitrogen of glutamine replaces oxygen of C-2 to form GMP (ATP dependent)
|
|
|
The intermediate of AMP production is...
|
adenylsuccinate
|
|
|
Fumarate leaves the reaction of...
|
adenylsuccinate to AMP
|
|
|
NADH and H+ leave the reaction of...
|
IMP to XMP
|
|
|
Glutamate, AMP, and PPi leave the reaction of...
|
XMP to GMP
|
|
|
Nucleotide kinases transfer phosphoryl groups to convert...
|
AMP, CMP, GMP, UMP to ATP, CTP, GTP, and UTP
|
|
|
Phosphoryl groups in the conversion of pyrimidines to energy come from...
|
phosphoenolpyruvate or ATP
|
|
|
UTP can be converted to CTP through...
|
CTP synthetase by adding glutamine, ATP, and H2O
|
|
|
The amine for CTP comes from...
|
glutamine
|
|
|
The conversion of UMP to TMP uses...
|
methylenetetrahydrofolate as a carbon donor
|
|
|
dUMP and methylenetetrahydrofolate are converted to dTMP and dihydrofolate using...
|
thymidylate synthase
|
|
|
We can make dNTPs from NTPs using...
|
ribonucleotide reductase and ribonucleotide diphosphates as substrates
|
|
|
In cytosine, the amino group comes from...
|
glutamine
|
|
|
In uridine, the NH group comes from...
|
glutamine
|
|
|
In uridine, the double bond comes from..
|
aspartate
|
|
|
When you have excess protein in your diet...
|
the amine nitrogens are discarded in the urea cycle and the carbons are salvaged
|
|
|
In glucogenic amino acids, the carbon of the carbon skeleton is...
|
converted to pyruvate or oxaloacetate
|
|
|
In ketogenic amino acids, the carbon of the carbon skeleton...
|
is eventually converted to acyl-CoA
|
|
|
Glucogenic amino acids include...
|
Ala, Arg, Asp, Asn, Cys, Glu, Gly, His, Met, Pro, Ser, Val
|
|
|
Ketogenic amino acids include...
|
Leu, Lys
|
|
|
Glucogenic/ketogenic amino acids include...
|
Ile, Phe, Thr, Trp, Tyr
|
|
|
In the breakdown of asparagine...
|
asparaginase is used to break it down to aspartae, and then transaminase is used to convert it to oxaloacetate
|
|
|
Serine loses its amino group to form...
|
pyruvate
|
|
|
Phenylalanine can be converted to tyrosine by...
|
phenylalanine hydroxylase
|
|
|
In the catabolism of phenylalanine, the phenylalanine is converted to ______, which is converted to _________ by _______, which is then converted by ________ to _________, which is converted by _______ to _________
|
1. tyrosine
2. p-hydroxyphenylpyruvate 3. transaminase 4. p-hydroxyphenylpyruvate dioxygenase 5. homogentisate 6. homogentisate dioxygenase 7. 4-maleylacetoacetate |
|
|
Those with phenylketonuria do not have...
|
phenylalanine hydroxylase
|
|
|
Those with alkaptonuria do not have...
|
homogentisate dioxygenase
|
|
|
Homogentisic acid is toxic and causes...
|
black urine
|
|
|
We get rid of excess nitrogen through the...
|
urea cycle
|
|
|
Mammals excrete...
|
urea
|
|
|
Birds and reptiles excrete...
|
uric acid
|
|
|
Fish excrete...
|
ammonia
|
|
|
The urea cycle consists of...
|
four reactions
|
|
|
Before the urea cycle occurs, _____ and ______ use ______ to change into _____ and _______; this occurs in the _____
|
1. amino acids
2. alpha-keto acids 3. transaminase 4. alpha-ketoglutarate 5. glutamate 6. cytosol |
|
|
Before the urea cycle occurs, _______ and _______ utilize _________ to get rid of ____ which binds with ______ through the enzyme ______ to form _______; this occurs in the ______
|
1. alpha-ketoglutarate
2. glutamate 3. gluatmate dehydrogenase 4. NH3 5. HCO3- 6. carbamoyl phosphate synthase 7. carbamoyl phosphate 8. mitochondrial matrix |
|
|
In the first step of the urea cycle, ______ combines with ______ to form ______ and this occurs in the _______
|
1. carbamoyl phosphate
2. ornithine 3. citrulline 4. mitochondrial matrix |
|
|
In the second step of the urea cycle, ______ is converted into _______ by combining with _______ and _______ from the ______ and this occurs in the _______
|
1. citrulline
2. arginosuccinate 3. ATP 4. aspartate 5. TCA cycle 6. cytosol |
|
|
In the third step of the urea cycle, _____ is converted to _____ by the exit of _____ which goes into the ______; this occurs in the ______
|
1. arginosuccinate
2. arginine 3. fumarate 4. TCA cycle 5. cytosol |
|
|
In the fourth step of the urea cycle, _____ is converted to ______ and _____ leaves; this occurs in the _______
|
1. arginine
2. ornithine 3. urea 4. cytosol |
|
|
When fumarate leaves the urea cycle, it goes through the _____ where it is converted to _____, then _____, then _______, which reenters; this all occurs in the _______
|
1. TCA cycle
2. malate 3. oxaloacetate 4. aspartate 5. mitochondrial matrix |
|
|
In the fourth step of the urea cycle, ______ is added into the reaction in order for ____ to leave
|
H2O; urea
|
|
|
Regulation of the events prior to the urea cycle is done by...
|
allosteric activation of carbamoyl phosphate synthetase
|
|
|
The mitochondria have transporters for...
|
citrulline and ornithine
|
|
|
The end of the arginine side chain looks just like...
|
urea
|
|
|
Toxic ammonia in the matrix is secreted out in the form of..
|
urea
|
|
|
Uric acid packs more...
|
nitrogen with less associated water than urea
|
|
|
Uric acid is the product of...
|
purine catabolism in mammals
|
|
|
Too much purines to dispose of causing uric acid crystallization in joints is...
|
gout
|
|
|
Purine bases can be converted to...
|
xanthine
|
|
|
Xanthine is converted to...
|
uric acid by xanthine oxidase
|
|
|
Urea is eventually converted back to...
|
ammonia by bacteria and fungi
|
|
|
Urea is broken down in bacteria and fungi by...
|
urease
|
|
|
Surplus amino acids are used as...
|
metabolic fuel
|
|
|
Fatty acids, ketone bodies, and glucose can be formed from...
|
amino acids
|
|
|
Major site of amino acid degradation is...
|
liver
|
|
|
The overall reaction of the urea cycle is:
|
CO2 + NH4 + 3ATP + aspartate + 2H2O ---> urea + 2ADP + 2 Pi + AMP + PPi + fumarate
|
|
|
Amino acids can become:
|
1. pyruvate
2. acetyl CoA 3. acetoacetyl CoA 4. alpha-ketoglutarate 5. succinyl CoA 6. fumarate 7. oxaloacetate |
|
|
Glutamate dehydrogenase is inhibited by...
|
high GTP and ATP levels
|
|
|
Glutamate dehydrogenase is stimulated by...
|
high GDP and ADP levels
|
|
|
Metabolism needs to be coordinated between...
|
different organs and tissues and different cellular compartments
|
|
|
Substances produced by one tissue that influence function of another tissue
|
hormones
|
|
|
Extracellular hormones influence intracellular function through use of...
|
signal transduction pathways
|
|
|
Hormones bind to ________ which activates _______ or _______
|
extracellular receptors; kinases; phosphatases
|
|
|
The making of ATP by breaking carbon bonds
|
catabolism
|
|
|
The usage of ATP by making carbon bonds
|
anabolism
|
|
|
Protein kinase substrates are usually...
|
tyrosine, serine, or threonine (all have -OH groups)
|
|
|
Insulin stimulates cells to...
|
take up glucose when glucose levels are high and suppress fatty acid release from fat cells as well as stimulate TAG synthesis
|
|
|
Insulin contains...
|
three disulfide bonds
|
|
|
The insulin receptor is a member of a large class of receptors called...
|
tyrosine kinase receptors
|
|
|
When insulin binds to the receptor...
|
GLUT4 opens to bring glucose in
|
|
|
The insulin receptor contains...
|
two alpha and two beta subunits
|
|
|
Insulin binding to the receptor causes...
|
a conformational change that brings subunits closer together, autophosphorylation occurs, and IRS-1 triggers a cascade of responses based upon glucose availability
|
|
|
Insulin binds to receptors on fat cells and triggers activation of...
|
extracellular lipoprotein lipase
|
|
|
Vesicle fusion triggered by insulin casuses...
|
an increase in the number of glucose transporters on cell surfaces
|
|
|
Immune system destroys pancreatic islet cells that produce insulin in...
|
type I diabetes
|
|
|
Not enough insulin production is...
|
type II diabetes
|
|
|
Low glucose levels causes...
|
glucagon release from the pancreas
|
|
|
Glucagon receptors are...
|
G protein receptors
|
|
|
When glucagon binds to the receptor, _____ is release and _____ binds causing ______ to dissociate and bind with _______, which causes _____ to be converted to _______
|
1. GDP
2. GTP 3. alpha domain 4. adenylate cyclase 5. ATP 6. cyclic AMP |
|
|
Cyclic AMP release in the cell signals that...
|
there is a hormone in the receptor
|
|
|
Cyclic AMP is a...
|
second messenger
|
|
|
Cyclic AMP can be removed by converting to...
|
AMP by phosphodiesterase
|
|
|
Epinephrine binds to...
|
beta-adrenergic receptor
|
|
|
Epinephrine response stimulates...
|
glycogen cleavage and glucose release from the liver
|
|
|
Epinephrine receptor is...
|
G protein complex
|
