1 CHAPTER 15: ANSWERS T SELECTED PRBLEMS SAMPLE PRBLEMS ( Try it yourself ) 15.1 ur bodies can carry out the second reaction, because it requires less energy than we get from breaking down a molecule of ATP. However, the first reaction requires substantially more than 7.3 kcal of energy, so ATP does not supply enough energy for the first reaction C 2 H H 2 2 C [H] 15.3 C 2 H H 2 + FAD + 5 NAD + 2 C 2 + FADH NADH + 5 H We obtain a total of 34.5 molecules of ATP. 12 NADH x 2.5 = 30 ATP 3 FADH 2 x 1.5 = 4.5 ATP Total = 34.5 ATP 15.5 Breaking down a molecule of myristic acid requires 6 cycles of beta oxidation, and produces 7 molecules of acetyl-coa We obtain 92 molecules of ATP when we break down one molecule of myristic acid. In Sample Problem 15.5, we found that breaking down myristic acid requires 6 beta oxidation cycles and produces 7 molecules of acetyl-coa: 6 cycles of beta oxidation produce 6 NADH + 6 FADH 2 7 citric acid cycles produce 21 NADH + 7 FADH ATP We make a total of = 27 molecules of NADH. 27 NADH x 2.5 = 67.5 molecules of ATP We make a total of = 13 molecules of FADH FADH 2 x 1.5 = 19.5 molecules of ATP Now we can add up all of the ATP. Remember that we made 7 ATP in the citric acid cycle, and we must break down 2 ATP to activate the fatty acid. 7 ATP (formed during the citric acid cycle) 67.5 ATP (from the oxidation of NADH) 19.5 ATP (from the oxidation of FADH 2 ) 2 ATP (broken down to activate the myristic acid) 92 ATP 15.7 We make 117 molecules of ATP when we oxidize a molecule of linoleic acid. Since linoleic acid contains two double bonds, we make two fewer molecules of FADH 2, which translates to 2 x 1.5 = 3 fewer molecules of ATP We make 19.5 moles of ATP when we burn 100 g of glycerol (the calculator answer is moles). The formula weight of glycerol is , so we make 18 moles of ATP when we burn g of glycerol: 18 moles ATP 100 g glycerol = 19.5 moles ATP g glycerol
2 15.9 Here are the structures of leucine and the product of the transamination. CH CH NH 3 CH C C C leucine transamination product The overall ATP yield is 26 molecules of ATP. 9 NADH x 2.5 = 22.5 ATP (from the oxidation of the NADH) 3 FADH 2 x 1.5 = 4.5 ATP (from the oxidation of the FADH 2 ) 1 ATP (formed by substrate-level phosphorylation) 1 NH + 4 x 2 = 2 ATP (broken down in the urea cycle) 26 ATP We must break down 800 molecules of ATP to make this protein. It takes 4 molecules of ATP to place one amino acid into the polypeptide chain: 200 amino acids x 4 = 800 ATP END F SECTIN PRBLEMS Section ATP stores the energy that is produces by catabolic reactions, and makes that energy available for anabolic reactions (and all other energy-requiring processes) ADP + P i + energy ATP + H This is an anabolic process, because it is building a large molecule from small pieces. Like all anabolic processes, building an enzyme absorbs energy ATP contains three phosphate groups, whereas ADP contains only two The first reaction requires energy from ATP. The chemical equation has the energy (3.4 kcal) on the left side, so the reaction consumes energy. (The second reaction produces energy and does not need any additional energy from ATP.) 15.6 The first reaction goes to completion, because ATP supplies more than enough energy for this reaction to occur. The second reaction requires more energy than ATP can supply, so it produces only a small concentration of product.
3 Section The carbon atoms become incorporated into C 2 molecules. The hydrogen atoms are transferred to a redox coenzyme (NAD + or FAD) The additional hydrogen atoms come from water molecules. (The oxygen atoms from water are used to make C 2.) 15.9 ur bodies oxidize NADH and FADH 2, producing energy that is stored in the form of ATP The molecular formula of 3-hydroxybutyric acid is C 4 H 8 3, and the chemical equation is: C 4 H H 2 4 C [H] C 4 H H FAD + 7 NAD + 4 C FADH NADH + 7 H + Four of the H atoms are transferred to FAD, so we need two molecules of FAD (remember that each FAD bonds to two H atoms) and we make two molecules of FADH 2. The other 14 hydrogen atoms are transferred to NAD +, but only 7 of them actually bond to NAD + (to make NADH); the other 7 become H + ions. Section Mitochondria carry out the oxidation reactions in a cell, harnessing the energy of these reactions to make ATP The electron transport chain is a sequence of reactions that removes hydrogen atoms from NADH and FADH 2 and transfers them to 2. The final products of the electron transport chain are NAD +, FAD, and H 2. In the process, the electron transport chain moves hydrogen ions through the inner membrane of the mitochondrion, producing a concentration gradient (that will be harnessed to make ATP) ATP synthase combines ADP with phosphate to make ATP. The enzyme gets the energy it needs by allowing H + ions to move back into the matrix, harnessing the energy of the concentration gradient The electrons come from the hydrogen atoms that were removed from NADH and FADH 2, and the end up on oxygen atoms (converting the oxygen into 2 ) In a concentration gradient, there is a higher concentration of a solute on one side of a membrane than on the other side. In a charge gradient, one side of a membrane has a higher concentration of positive ions than negative ions, and the other side has a higher concentration of negative ions than positive ions. The electron transport chain produces both types of gradient by moving H + across the inner membrane. The concentration of H + becomes higher outside the membrane than inside the membrane (a concentration gradient). In addition, the extra H + outside the membrane produces an excess of positive charge, while the missing H + inside the membrane leaves an excess of negative charge (a charge gradient).
4 15.17 The electron transport chain moves 10 H + ions for each NADH that it oxidizes, so it moves a total of 10 x 4 = 40 H + ions when it oxidizes four molecules of NADH. Four H + ions must return to the matrix for each ATP that is made available to the cell, so the cell will gain a total of 40 4 = 10 molecules of ATP The fourth hydrogen ion is used to transport ATP out of the mitochondrion The cell will obtain 8 molecules of ATP. 2 NADH x 2.5 = 5 ATP 2 FADH 2 x 1.5 = 3 ATP Total = 8 ATP Section In an activation reaction, a cell uses energy from ATP to build a high-energy molecule (usually a compound that contains a phosphate group attached to an organic fragment). The ATP breaks down into ADP and phosphate In glycolysis, glucose is broken down into two pyruvate ions Lactic acid fermentation is anaerobic because it does not make any NADH or FADH 2, so the body does not require oxygen when it carries out this pathway. Any pathway that makes NADH or FADH 2 requires oxygen, because these coenzymes must be converted back into NAD + and FAD. The electron transport chain uses oxygen from the air to do this The NADH for this reaction is made in one of the earlier reactions of glycolysis Normal glycolysis makes 2 molecules of ATP and two molecules of NADH A substrate-level phosphorylation is a reaction that makes ATP without involving the electron-transport chain Two of the reactions of glycolysis break down a molecule of ATP into ADP and phosphate. Therefore, when we break down one molecule of glucose to pyruvate ions, our net gain is two molecule of ATP (i.e. we end up with two more molecules of ATP than we started with). Section NAD + + HS CoA C C H C S CoA + C 2 + NADH + H +
5 15.28 There are two decarboxylation reactions in the citric acid cycle (reactions 3 and 4). This is reasonable, because the citric acid cycle must convert citrate ion into oxaloacetate ion. Citrate ion contains six carbon atoms and oxaloacetate ion contains only four, so the citric acid cycle must remove two carbon atoms from the original citrate skeleton There are four oxidation steps in the citric acid cycle (reactions 3, 4, 6 and 8). This is reasonable, because each oxidation step produces two hydrogen atoms (bonded to NAD or FAD), and the overall cycle must produce eight hydrogen atoms The first step of the cycle combines the acetyl group with oxaloacetate ion. The product of this reaction is citrate ion The alcohol group in citrate is a tertiary alcohol, so it cannot be oxidized. Step 2 of the citric acid cycle converts the tertiary alcohol to a secondary alcohol, so the alcohol group can be oxidized in the next step The citric acid cycle produces three molecules of NADH, one molecule of FADH 2, and one molecule of ATP. (Actually, the cycle produces GTP rather than ATP, but these two compounds are functionally equivalent to one another.) A total of 10 molecules of ATP are formed when one molecule of acetyl-coa is broken down As shown on page 15-33, a total of 32 molecules of ATP are formed when one molecule of glucose is broken down. Four of these ATP molecules are made by substrate-level phosphorylations (two in glycolysis and two in the citric acid cycle), so the other 28 ATP molecules are formed by oxidative phosphorylation. Section C 18 H H 2 18 C [H] This reaction activates the fatty acid so it can be broken down into acetyl-coa ( ) 10 C S CoA + FAD ( ) 10 CH CH C S CoA + FADH 2 H ( ) 10 CH CH C S CoA + H 2 ( ) 10 CH C S CoA H ( ) 10 CH C S CoA + NAD + ( ) 10 C C S CoA + NADH + H + ( ) 10 C C S CoA + HS-CoA ( ) 10 C S CoA + C S CoA
6 15.38 Stearic acid contains 18 carbon atoms, so 8 cycles of beta oxidation are required to break it down, and 9 molecules of acetyl-coa are formed The total ATP yield is 120 molecules of ATP. 8 cycles of beta oxidation produce 8 NADH + 8 FADH 2 9 citric acid cycles produce 27 NADH + 9 FADH ATP We make a total of = 35 molecules of NADH. 35 NADH x 2.5 = 87.5 molecules of ATP We make a total of = 17 molecules of FADH FADH 2 x 1.5 = 25.5 molecules of ATP Now we can add up all of the ATP. Remember that we made 9 ATP in the citric acid cycle, and we must break down 2 ATP to activate the fatty acid. 9 ATP (formed during the citric acid cycle) 87.5 ATP (from the oxidation of NADH) 25.5 ATP (from the oxidation of FADH 2 ) 2 ATP (broken down to activate the stearic acid) 120 ATP Your body makes 42.2 moles of ATP (the calculator answer is moles). The molecular formula of stearic acid is C 18 H 36 2, and the formula weight is The calculation is: 120 moles ATP 100 g stearic acid = 42.2 moles ATP g stearic acid (In Problem 15.39, we found that we get 120 molecules of ATP from one molecule of stearic acid.) For each double bond in an unsaturated fatty acid, we lose one molecule of FADH 2, because the dehydrogenation step of beta oxidation will not occur when a double bond is already present. Section This reduces the number of different reactions our bodies must carry out. As a result, we do not need to make as many different enzymes. Building an enzyme requires a lot of energy, so we reduce the amount of energy we must expend to break down amino acids SH CH C The ion is ammonium ion (NH 4 + ) The urea cycle converts ammonium ions into the NH 2 groups of urea. Urea is much less toxic than ammonium ion, so we can store urea rather than excreting it continuously.
7 15.46 It takes two molecules of ATP to incorporate one NH 4 + ion into urea The liver converts most of the amino acids into glucose (removing nitrogen and sulfur atoms as needed) and releases the glucose into the blood, where it can be used as fuel by other cells The overall yield is 23 molecules of ATP. 8 NADH x 2.5 = 20 ATP (from the oxidation of the NADH) 2 FADH 2 x 1.5 = 3 ATP (from the oxidation of the FADH 2 ) 2 ATP (formed by substrate-level phosphorylation) 1 NH 4 + x 2 = 2 ATP (broken down in the urea cycle) 23 ATP (The C 2 is a waste product and is not used to make additional ATP.) Succinyl-CoA is also the product of one of the reactions of the citric acid cycle. Therefore, when a cell burns valine, it must make the enzymes that convert valine into succinyl- CoA, but it does not need to make additional enzymes to oxidize the succinyl-coa, since they are already present as part of the citric acid cycle. Section ur bodies can use amino acids and lactic acid to build glucose, but we cannot use fatty acids Gluconeogenesis is a sequence of reactions that converts pyruvate ions into glucose The liver carries out gluconeogenesis in the following situations: 1) immediately after a meal, to help replenish the glycogen supply in the liver 2) when the concentration of lactate in the blood is high as a result of heavy exercise 3) during a prolonged fast, to maintain an appropriate blood glucose level ur body breaks down 6 molecules of ATP and 2 molecules of NADH to convert pyruvate into glucose. In contrast, we obtain only 2 molecules of ATP and 2 molecules of NADH when we break down glucose into pyruvate It takes 2 molecules of ATP to add a molecule of glucose to a glycogen chain a) The body activates a fatty acid by linking it to coenzyme A. This reaction consumes two molecules of ATP. (Note that when we build a triglyceride, we must activate three molecules of fatty acid.) b) The body activates glycerol by linking it to a phosphate group, forming glycerol-1- phosphate. This reaction consumes one molecule of ATP.
8 15.56 A futile cycle is a pair of metabolic pathways that occur at the same time and that undo one another (wasting energy in the process). ne pathway builds a molecule, while the other breaks the molecule down Cells prevent futile cycles by using different enzymes for each pathway, and by carrying out the pathways in different locations in the cell A high concentration of ATP should have the opposite effect on enzymes 1 and 2, to prevent a futile cycle. Therefore, a high concentration of ATP should speed up enzyme 2. CUMULATIVE PRBLEMS (dd-numbered problems only) Some examples of catabolic pathways are glycolysis, the citric acid cycle, and the beta oxidation of fatty acids. All of these pathways (and all other catabolic pathways) produce energy a) This is an anabolic pathway, since it builds a large molecule from small pieces. b) Like all anabolic pathways, this pathway breaks down ATP to supply the needed energy ATP contains adenosine bonded to three phosphate groups, and ADP is similar but contains only two phosphate groups. P i P i P i adenosine adenosine P i P i ATP ADP This reaction produces a similar amount of energy to the breakdown of ATP, because both reactions break the bond between two phosphate groups The first reaction can be harnessed to make a molecule of ATP (from ADP and phosphate), because it produces more than 7.3 kcal of energy The enzymes of the electron transport chain remove electrons from NADH and FADH 2, and pass these electrons from one enzyme to another, eventually placing them on an oxygen atom. Each enzyme simultaneously pumps hydrogen ions from the mitochondrial matrix to the intermembrane space, using the energy from the electron transport reactions to carry out this active transport The products of this reaction are NAD +, an H + ion, and two electrons. The chemical equation is: NADH NAD + + H e A total of ten hydrogen ions are transferred through the inner membrane.
9 15.75 Mitochondria can break down stearic acid and phenylalanine to produce energy. They cannot break down glucose, because the enzymes of glycolysis are located in the cytosol Choices b, c and d all produce energy that is used to make ATP H 2 C 4 H H 2 4 C [H] The mitochondrion can make 10 molecules of ATP. Mitochondria can make 2.5 molecules of ATP for each NADH that they oxidize, so 2.5 x 4 = 10 ATP The total ATP yield is 12.5 molecules of ATP. 4 NADH x 2.5 = 10 ATP (from the oxidation of NADH) 1 FADH 2 x 1.5 = 1.5 ATP (from the oxidation of FADH 2 ) 1 ATP (formed by substrate-level phosphorylation) Total = 12.5 ATP The starting materials are glucose, 2 molecules of ADP, 2 phosphate ions, and 2 molecules of NAD +. The products are 2 pyruvate ions, 2 molecules of ATP, and 2 molecules of NADH. (I ve ignored hydrogen ions in this answer.) This is an example of alcoholic fermentation, in which the starch is broken down into ethanol and C 2. The C 2 is responsible for the fizz in the beer a) The starting materials are glucose, 2 molecules of ADP, and 2 phosphate ions. The products are 2 lactate ions and 2 molecules of ATP. b) Two molecules of ATP are produced for each molecule of glucose that breaks down The breakdown of acetyl-coa produces 10 molecules of ATP (via the citric acid cycle) Four molecules of ATP are produced in substrate-level phosphorylations (two during glycolysis and two during the citric acid cycle). The other 28 ATP molecules are made by oxidative phosphorylation. 4 ATP Percentage of ATP formed by substrate - level phosphorylations : 100% = 12.5% Percentage of ATP formed by oxidative phosphorylation: 28 ATP 32 ATP 32 ATP 100% = 87.5% We get 12.5 molecules of ATP when we break down one oxaloacetate ion. The first reaction (breaking oxaloacetate into pyruvate and C 2 ) does not make a high-energy molecule, so oxaloacetate ion and pyruvate ion give us the same number of ATP molecules: xidative decarboxylation of pyruvate: 1 NADH Citric acid cycle: 3 NADH, 1 FADH 2, 1 ATP Total high-energy molecules: 4 NADH, 1 FADH 2, 1 ATP 4 NADH x 2.5 = 10 ATP 1 FADH 2 x 1.5 = 1.5 ATP Total ATP = = 12.5
10 15.97 a) We get 80 molecules of ATP when we break down three molecules of ribose. It helps to think of this in two steps. Step 1: breaking down 3 ribose molecules into 5 pyruvate ions This step produces 5 NADH and 5 ATP for every three molecules of ribose. Step 2: breaking down 5 pyruvate ions into C 2 As we saw in problem 15.95, we get 4 NADH, 1 FADH 2, and 1 ATP when we break down one pyruvate ion. Since we are breaking down five pyruvate ions, we get a total of 20 NADH, 5 FADH 2, and 5 ATP. Now we can work out the total: 5 NADH in step NADH in step 2 = 25 NADH total no FADH 2 in step FADH 2 in step 2 = 5 FADH 2 total 5 ATP in step ATP in step 2 = 10 ATP total Finally, we account for oxidative phosphorylation: 25 NADH x 2.5 = 62.5 ATP 5 FADH 2 x 1.5 = 7.5 ATP Total ATP = = 80 ATP b) In part a, we saw that we get 80 molecules of ATP from three molecules of ribose. For one molecule of ribose, we get 80 3 = 26.7 molecules of ATP C 18 H H 2 18 C [H] a) The ATP yield is 50 molecules of ATP from one molecule of caprylic acid. Caprylic acid has eight carbon atoms, so it must undergo three cycles of beta oxidation, which produce four molecules of acetyl-coa. 3 cycles of beta oxidation produce 3 NADH + 3 FADH 2 4 citric acid cycles produce 12 NADH + 4 FADH ATP We make a total of = 15 molecules of NADH. 15 NADH x 2.5 = 37.5 molecules of ATP We make a total of = 7 molecules of FADH 2. 7 FADH 2 x 1.5 = 10.5 molecules of ATP Now we can add up all of the ATP. Remember that we made 4 ATP in the citric acid cycle, and we must break down 2 ATP to activate the fatty acid. 4 ATP (formed during the citric acid cycle) 37.5 ATP (from the oxidation of NADH) 10.5 ATP (from the oxidation of FADH 2 ) 2 ATP (broken down to activate the caprylic acid) 50 ATP b) We get four molecules of ATP from substrate-level phosphorylations (the four ATP molecules that are formed in the citric acid cycle) The overall yield is 336 molecules of ATP (wow!). Table 15.6 (on page 15-50) gives the ATP yield from one molecule of glycerol as 18 molecules of ATP. We can calculate the ATP yield from palmitic acid in the usual fashion, noting first that palmitic acid contains 16 carbon atoms, so it requires 7 cycles of beta oxidation and produces 8 molecules of acetyl-coa. For one molecule of palmitic acid, we get:
11 7 cycles of beta oxidation produce 7 NADH + 7 FADH 2 8 citric acid cycles produce 24 NADH + 8 FADH ATP We make a total of = 31 molecules of NADH. 31 NADH x 2.5 = 77.5 molecules of ATP We make a total of = 15 molecules of FADH FADH 2 x 1.5 = 22.5 molecules of ATP Now we can add up all of the ATP we get from a molecule of palmitic acid. Remember that we made 4 ATP in the citric acid cycle, and we must break down 2 ATP to activate the fatty acid. 8 ATP (formed during the citric acid cycle) 77.5 ATP (from the oxidation of NADH) 22.5 ATP (from the oxidation of FADH 2 ) 2 ATP (broken down to activate the palmitic acid) 106 ATP (from one molecule of palmitic acid) Finally, we can calculate the overall ATP yield. We get 106 x 3 = 318 molecules of ATP from the three molecules of palmitic acid, and we get an additional 18 molecules of ATP from the glycerol, giving us a total of = 336 molecules of ATP You get 41.6 moles of ATP per 100 grams of tripalmitin. The formula weight of tripalmitin is , so the calculation is: 336 moles ATP 100 g tripalmitin = 41.6 moles ATP g tripalmitin C 5 H 11 N H 2 + H + 5 C 2 + NH [H] CH CH NH 3 CH C leucine C C transamination product NH 3 CH NH 3 CH C NH 3 CH C lysine transamination product
12 The overall yield is 10.5 molecules of ATP. 4 NADH x 2.5 = 10 ATP (from the oxidation of NADH) 1 FADH 2 x 1.5 = 1.5 ATP (from the oxidation of FADH 2 ) 1 ATP (formed directly during the pathway) Total ATP formed = = 12.5 ATP The NH 4 + ion is metabolized in the urea cycle, which consumes 2 ATP. We must subtract this from the total to get the overall ATP yield. verall ATP yield = = 10.5 ATP Glutamine contains a nitrogen atom in the side chain, while glutamic acid does not. When your body breaks down glutamine, it must remove the nitrogen from the amide group in the side chain. This amide nitrogen is removed in the form of NH 4 +, which is then processed by the urea cycle. The urea cycle consumes 2 molecules of ATP, so the overall ATP yield for glutamine is two molecules of ATP less than the yield for glutamic acid. C NH 2 C to the urea cycle + H 2 + NH 4 + NH 3 CH C glutamine NH 3 CH C glutamic acid The reaction given in the problem makes one molecule of NADH and one molecule of FADH 2, and it breaks down one molecule of ATP. It also makes a NH 4 + ion, which must be processed by the urea cycle. The net ATP yield from this reaction is 1 molecule of ATP, as shown below: 2.5 ATP (from NADH) ATP (from FADH 2 ) 1 ATP (broken down in the reaction) 2 ATP (broken down in the urea cycle) 1 ATP (overall yield from the reaction in the problem) The three molecules of acetyl-coa are broken down to C 2 by the citric acid cycle. The citric acid cycle makes one ATP, three NADH, and one FADH 2 each time it consumes a molecule of acetyl-coa. Since we have three molecules of acetyl-coa, we multiply these amounts by three: we get 3 ATP, 9 NADH, and 3 FADH 2. Converting these into ATP: 9 NADH x 2.5 = 22.5 ATP (from NADH) 3 FADH 2 x 1.5 = 4.5 ATP (from FADH 2 ) +3 ATP (formed directly) 30 ATP (total from the citric acid cycle) The grand total is = 31 ATP from the breakdown of one molecule of leucine.
13 The reaction in the problem makes one molecule of NADH and one NH 4 + ion. We get 2.5 ATP from the NADH, but we must break down 2 ATP to deal with the NH 4 + ion, so the net yield of ATP from this reaction is = 0.5 ATP. This reaction also makes a molecule of pyruvate. Your body first converts pyruvate into acetyl- CoA, making one molecule of NADH in the process. This NADH gives you an additional 2.5 molecules of ATP. You then break down acetyl-coa via the citric acid cycle, which gives 3 NADH, 1 FADH 2, and 1 ATP. The overall ATP yield from the citric acid cycle is 10 ATP (7.5 from the NADH, 1.5 from the FADH 2, and 1 formed directly). The grand total is = 13 molecules of ATP a) The ATP yield is 22.2 moles of ATP per 100 g of valine (the calculator answer is ). The molecular formula of valine is C 5 H 11 N 2, and the formula weight of valine is The calculation is: 26 moles ATP 100 g valine = 22.2 moles ATP g valine b) The ATP yield is 26.2 moles of ATP per 100 g of valine (the calculator answer is ). When we use valine within a polypeptide, the molecular formula is C 5 H 9 N, and the formula weight is The calculation is: 100 g valine = 26.2 moles ATP 26 moles ATP g valine There is no pathway that converts acetyl-coa into glucose. (Acetyl-CoA can be broken to C 2 by the citric acid cycle, and it can be used to build fatty acids, but it cannot be used to build carbohydrates.) Therefore, leucine can be converted to fatty acids, or burned to produce energy, but it cannot be converted to glucose a) Glycolysis is involved in the metabolism of carbohydrates. b) Beta oxidation is involved in the metabolism of fatty acids. c) The citric acid cycle is involved in the metabolism of all three types of nutrients. d) Transamination is involved in the metabolism of amino acids Pathway Starting material Final product Glycolysis glucose pyruvate ions Beta oxidation fatty acid and coenzyme A acetyl-coa Citric acid cycle acetyl-coa C 2 Transamination an amino acid and an α-ketoacid (usually α-ketoglutarate) a different α-ketoacid and a different amino acid (usually glutamic acid) ur bodies cannot convert fatty acids into glucose because there is no reaction that converts acetyl-coa into pyruvate. We can break down fatty acids into acetyl-coa, and we can convert pyruvate into glucose, but we have no way to connect these two pathways.
14 a) We must break down two molecules of ATP to activate a fatty acid. b) When we activate a fatty acid, we make a fatty-acyl CoA Breaking down one molecule of palmitic acid into eight molecules of acetyl-coa requires seven cycles of beta oxidation. Each cycle produces 1 NADH and 1 FADH 2, so we make a total of 7 NADH and 7 FADH 2. In addition, we must activate the palmitic acid before we can carry out beta oxidation, so we must break down 2 ATP. The net ATP yield is: 7 NADH x 2.5 = 17.5 ATP 7 FADH 2 x 1.5 = 10.5 ATP Total = 28 ATP formed 2 ATP broken down = 26 ATP The problem tells us that we break down 44 molecules of ATP when we build palmitic acid from acetyl-coa. Therefore, the futile cycle consumes = 18 molecules of ATP a) Citrate is a negative effector for one enzyme in glycolysis, and a positive effector for one enzyme in gluconeogenesis. Therefore, the concentration of citrate helps to control which pathway predominates. When the concentration of citrate is high, gluconeogenesis is fast and glycolysis is slow. When the concentration of citrate is low, glycolysis is fast and gluconeogenesis is slow. b) We can predict that citrate will have the effect that it does on FBP and PFK. When the concentration of citrate is low, the cell cannot carry out the citric acid cycle to make ATP. Therefore, when the concentration of citrate is low, the cell needs to make more citrate. It can do so by carrying out glycolysis, so a low citrate concentration should speed up glycolysis. (If a low citrate concentration slowed down glycolysis, the cell could not obtain energy when it needed to!). In contrast, when the concentration of citrate is high, the cell does not need to make more citrate, so it slows down glycolysis. It also speeds up gluconeogenesis, which converts pyruvate into glucose and prevents the pyruvate from being converted to acetyl-coa (which must then form citrate) Acetyl-CoA is a negative effector of pyruvate kinase. When the cell has a high concentration of acetyl-coa, it does not need to make more acetyl-coa. Pyruvate kinase converts PEP into pyruvate, which is normally broken down into acetyl-coa and C 2. The cell does not need more acetyl-coa, so pyruvate kinase slows down a) Immediately after a meal, the concentrations of both glucose and amino acids in the blood increase. The liver does not need to supply glucose to the blood, so it absorbs excess amino acids from the blood, converts them to glucose (that s the gluconeogenesis pathway), and uses the glucose to build glycogen for storage. b) A couple of hours after the meal, the excess amino acids have been broken down, so gluconeogenesis stops. (The liver is now breaking down glycogen into glucose and delivering the glucose to the bloodstream.) c) After 12 hours or so, the liver has broken down most of its glycogen. It must continue to deliver glucose to the blood, because the brain needs a constant supply of glucose. Therefore, the liver begins to carry out gluconeogenesis once again, using amino acids (from the breakdown of body proteins) to build glucose.
15 a) You make roughly 61 g of ethanol (the calculator answer is g). The molecular formulas for glucose and ethanol are C 6 H 12 6 and C 2 H 6, respectively. The balanced equation for alcoholic fermentation is: C 6 H C 2 H C 2 The formula weight of glucose is , and the formula weight of ethanol is The reaction produces two molecules of ethanol, so the relative weights are g of glucose to g of ethanol. Use this relationship as a conversion factor: g ethanol 120 g glucose = 61 g ethanol g glucose b) You make roughly 59 g of C 2 (the calculator answer is g). The formula weight of C 2 is 44.01, and the reaction calls for two molecules of C 2, so the relative weights are g of glucose to g of C 2 : g C 120 g glucose 2 = 59 g C g glucose c) The volume of the C 2 is roughly 32 liters (the calculator answer is liters). We first convert the mass of C 2 into moles: 1 mole g C 2 = moles of C g Then we convert the moles of C 2 into liters, using the fact that 1 mole occupies 24 liters: 24 L moles = 32 L 1 mole a) Here are the ATP yields for each of the amino acids in casein: 9 ala x 13 = 117 ATP 6 arg x 23.5 = 141 ATP 8 asn x 11 = 88 ATP 7 asp x 13 = 91 ATP 25 glu x 20.5 = ATP 14 gln x 18.5 = 259 ATP 9 gly x 5.5 = 49.5 ATP 5 his x 19 = 95 ATP 11 ile x 33.5 = ATP 17 leu x 32.5 = ATP 14 lys x 30 = 420 ATP 5 met x 21.5 = ATP 8 phe x 32 = 256 ATP 17 pro x 23 = 391 ATP 16 ser x 10.5 = 168 ATP 5 thr x 18 = 90 ATP 2 trp x 35 = 70 ATP 10 tyr x 34.5 = 345 ATP 11 val x 26 = 286 ATP Adding all of these numbers gives molecules of ATP from one molecule of casein.
16 b) There are a total of 199 amino acids in casein. The ATP yield per amino acid is then = 22.1 molecules of ATP per amino acid (the calculator answer is ). c) The ATP yield is 19.2 moles of ATP per 100 g of casein (the calculator answer is ): moles ATP 100 g casein = 19.2 moles ATP g casein d) The ATP yield for casein is similar to that of starch, and much less than that of tristearin. This agrees with the nutritional energy values for proteins, carbohydrates, and fats; the values for protein and carbohydrate are the same (4 Cal per gram) and the value for fats is more than twice as high (9 Cal per gram).
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Take notes while watching the following video tutorials to prepare for the Metabolism Part 2 Activity. Metabolism and Bioenergetics Part 1: Intro and Acetyl CoA Metabolism ALL biochemical reactions involving
How is a Marathoner Different from a Sprinter? Long-distance runners have many slow fibers in their muscles Slow fibers break down glucose aerobically (using oxygen) for ATP production These muscle cells
Cellular respiration So why do we breathe? The big picture Heterotrophs cannot make their own food to supply their energy needs Instead they break down food to use the chemical energy stored in organic
9-1 Notes Chemical Pathways Chemical Energy & Food Food provides living things with the chemical building blocks to grow and reproduce. One gram of the sugar glucose releases 3811 calories of heat energy.
Energy flows into an ecosystem as sunlight and leaves as heat Photosynthesis makes O 2 and organic molecules (like sugars and proteins), which are used in cellular respiration Cells use chemical energy
Scott K. Powers Edward T. Howley Theory and Application to Fitness and Performance SEVENTH EDITION Chapter Presentation prepared by: Brian B. Parr, Ph.D. University of South Carolina Aiken Copyright 2009
LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 9 Cellular Respiration and Fermentation
Summary of Metabolic Pathways (Ch 21,23 and 25) 21.1 Energy and Life Energy can be converted from one form to another, but can t be created or destroyed. -A consequence of this is that we need a constant
Name Advanced Biology Enzyme and Cellular Respiration Test Part I Multiple Choice (75 points) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The
Introduction Chapter 6 In eukaryotes, cellular respiration harvests energy from food, yields large amounts of, and Uses to drive cellular work. A similar process takes place in many prokaryotic organisms.
Part 1: Multiple Choice SBI4U: Respiration and Photosynthesis Test Mr. Dykstra Name: [25 marks] 1. Which of the following molecules links glucose oxidation, fatty acid catabolism, and the catabolism of
Ch. 6 Cellular Respiration Name Period California State Standards covered by this chapter: Cell Biology 1. The fundamental life processes of plants and animals depend on a variety of chemical reactions
How Cells Release Chemical Energy Cellular Respiration Overview of Carbohydrate Breakdown Pathways Photoautotrophs make ATP during photosynthesis and use it to synthesize glucose and other carbohydrates
An outline of glycolysis. Each of the 10 steps shown is catalyzed by a different enzyme. Note that step 4 cleaves a six-carbon sugar into two three-carbon sugars, so that the number of molecules at every
Lactic Acid Dehydrogenase Pyruvic Acid Dehydrogenase Complex Pyruvate to ACETYL coa CC CoA + CO 2 Mitochondria 3 carbon Pyruvate to 2 carbon ACETYL Coenzyme A Pyruvate Acetyl CoA + CO 2 + NADH + H + CO2
THE CELLULAR RESPIRATION SAGA II: THE CITRIC ACID CYCLE & OXIDATIVE PHOSPHORYLATION PLAYERS OF CELLULAR RESPIRATION NAD+ is a coenzyme that is reduced to using electrons Becomes reduced + H NAD + H + H
Chapter 9 Cellular Respiration Section 9 1 Chemical Pathways (pages 221 225) This section explains what cellular respiration is. It also describes what happens during a process called glycolysis and describes
Chapter 5 Fundamentals of Human Energy Transfer Slide Show developed by: Richard C. Krejci, Ph.D. Professor of Public Health Columbia College 6.18.11 Objectives 1. Describe the first law of thermodynamics
Phases of aerobic cellular respiration 1. Glycolysis 2. Transition or Acetyl-CoA reaction 3. Krebs cycle 4. Electron transport system Chapter 7 Cellular Respiration These phases are nothing more than metabolic
Cellular Respiration INTRODUCTION TO CELLULAR RESPIRATION Nearly all the cells in our body break down sugars for ATP production Most cells of most organisms harvest energy aerobically The aerobic harvesting
Chapter 6 How Cells Harvest Chemical Energy Standard 1.g. Cellular Respiration Is the main way that chemical energy is harvested from food and converted to ATP Is an aerobic process Yields The Relationship
GCE A Level Biology Energy and respiration сᴏᴏʟιᴏ 2013-2014 Q 1(a) Describe how ATP is synthesized by oxidative phosphorylation. [June 2012 # 1] Reduced NAD and reduced FAD are passed to the electron transport
Oxidation of Pyruvate and the Citric Acid Cycle Bởi: OpenStaxCollege If oxygen is available, aerobic respiration will go forward. In eukaryotic cells, the pyruvate molecules produced at the end of glycolysis
Metabolism Cellular Metabolism Consists of all of the chemical reactions that take place in a cell Biol 105 Lecture 6 Read Chapter 3 (pages 63 69) Cellular Metabolism Aerobic cellular respiration requires
Harvesting Energy: Glycolysis and Cellular Respiration Chapter 8 Overview of Glucose Breakdown The overall equation for the complete breakdown of glucose is: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP The
CHAPTER 9 CELLULAR RESPIRATION: HARVESTING CHEMICAL ENERGY Section C: Related Metabolic Processes 1. Fermentation allows some cells to produce ATP without the help of oxygen 2. Glycolysis and the Krebs
Transfers of electrons during chemical reactions (oxidation-reduction reactions) Relocation of electrons in food molecules releases energy which can be used to synthesize ATP ATP is used to do ALL types
Biology I Cellular Respiration Name: Date: Hour: OK OK OK.. I m sure you all thought that I wouldn t possibly ask you to know more for this chapter SORRY! Now, we need a place to disassemble the molecule
008 Chapter 8 Student: 1. Some bacteria are strict aerobes and others are strict anaerobes. Some bacteria, however, are facultative anaerobes and can live with or without oxygen. If given the choice of
ellular Respiration ellular Respiration A catabolic, exergonic, oxygen (O 2 ) requiring process that uses energy extracted from macromolecules (glucose) to produce energy (ATP) and water (H 2 O). 6 H 12
Cellular Respiration: How Cells Use Stored Energy Chapter 8 Killer Bees Descendents of African honeybees that were imported to Brazil in the 1950s More aggressive, wider-ranging than other honeybees Africanized
THE CITRIC ACID CYCLE Introduction In this Cbse Biology Notes on the Citric Acid Cycle, also called the Krebs Cycle, we will pick up where we left off in the last section with the aerobic product of glycolysis,
Cellular respiration - how cells make energy - Oxygen is needed for cellular respiration [OVERHEAD, fig. 6.2, p. 90 / 4th: 6.1] - ATP - this is provided by the lungs - lungs provide oxygen to blood, blood
Pathways that Harvest and Store Chemical Energy Chapter 6 Pathways that Harvest and Store Chemical Energy Key Concepts 6.1 ATP, Reduced Coenzymes, and Chemiosmosis Play Important Roles in Biological Energy
Chapter 9 & 24 Muscle Metabolism Annie Leibovitz/Contact Press Images Introduction: Muscle Metabolism Energy for Contraction Energy is never created nor destroyed, only stored or released Bonds = energy
Chemical Reactions and Enzymes Do Now Photosynthesis and Respiration 4 Minutes Share Out What is SUCCESS? Success is not gained by defeat Success does not occur over night Success can emerge at anytime
IX. Metabolism and Energy Production A. Introduction Slide 1. R `ism a. Stage I: Breakdown of macromolecules into their building blocks (1) Proteins amino acids (2) Polysaccharides, disaccharides monosaccharides
Chapter 5 Metabolism: Aerobic Respiration Dr. Amy Rogers Bio 139 Fall 2006 Office Hours: Mondays & Wednesdays, 8:30-10:00 AM Some figures taken from Krogh Biology: A Guide to the Natural World Bacterial
Harvesting Energy: and Cellular Chapter 8 Using the Energy from Photosynthesis 6CO 2 + 6H 2 O + light C 6 H 12 O 6 + 6O 2 + heat Some ATP is produced in photosynthesis, but most energy is stored in sugars.
3 Cell Metabolism Chapter 3 Cell Metabolism - review Student Learning Outcomes: Describe central role of enzymes as catalysts Vast array of chemical reactions Many enzymes are proteins Role of NAD + /NADH
1. Glycolysis leads to the production of and two molecules of ATP. In the absence of oxygen, fermentation leads to the production of. Glycolysis plus the citric acid cycle can convert the carbons of glucose
Copyright! The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 22.1 The Mitochondria Denniston Topping Caret 5 th Edition Chapter 22 Aerobic Respiration and Energy Production
Slide 1 Chapter 9 Cellular Respiration: Harvesting Chemical Energy PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley
Ch23_PT MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) All of the following statements concerning digestion are correct except A) The major physical
Chapter 8: pp. 133-149 BIOLOGY 10th Edition Cellular Respiration Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Insert figure 8. here and Cytoplasm e F ADH Mitochondrion
Cellular Respiration So, all living things need energy in order to stay alive. The transformation of energy and matter in the body is called metabolism. Metabolism involves anabolic (build-up) and catabolic
OpenStax-CNX module: m47334 1 Oxidation of Pyruvate and the Citric Acid Cycle Robert Bear David Rintoul Based on Oxidation of Pyruvate and the Citric Acid Cycle by OpenStax College This work is produced
OpenStax-CNX module: m44433 1 Oxidation of Pyruvate and the Citric Acid Cycle OpenStax College This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 3.0 By the
Chapter 16 The Citric Acid Cycle Multiple Choice Questions 1. Which of the following is not true of the reaction catalyzed by the pyruvate dehydrogenase complex? A) Biotin participates in the decarboxylation.
MULTIPLE CHOICE: Circle ALL that are TRUE. There may be MORE THAN one correct answer. is the first step in cellular respiration that begins releasing energy stored in glucose. A. Alcoholic fermentation
Chapter 18 Metabolic Pathways and Energy Production 1 Metabolism Metabolism involves all chemical reactions that provide energy and substances needed for growth catabolic reactions that break down large,
Microbiology - Problem Drill 05: Microbial Metabolism No. 1 of 10 1. Anabolism is a metabolic process where are turned into molecules. (A) Complex, simple (B) Simple, ATP (C) Simple, ATP (D) Simple, complex
Anabolic pathway that makes glucose from pyruvate Net result = reverse of glycolysis Three topics: 1. Thermodynamics 2. Enzymes 3. Regulation 1. Thermodynamics Reversing glycolysis requires energy to pump
Enzymes and Metabolic Pathways Un-lecture.part II NOTE: number corresponds to slides posted on the website. 44. ETS and Oxidative phosphorylation: When we completed the Krebs cycle, all of the bonds between
Introduction to Biology Respiration Chapter 5 Introduction Being alive is work. Cells organize small organic molecules into polymers such as the proteins, carbohydrates, and so forth you studied last week.
Pyruvate Oxidation and the Krebs Cycle Courtney, Chelsey, Morgan, GSchilbeG, Tessa Pyruvate Oxidation Pyruvate Oxidation Pyruvate is a glucose molecule cut in half Pyruvate oxidation is the second stage
http://www.youtube.com/watch?v=vcpnk92uswy What s the point? Cellular Respiration The point Stage 4: is to make ATP! Electron Transport Chain ATP 2013-2014 Cellular respiration ATP accounting so far Even
1 Cellular Respiration Chapter 9 2 Introduction Living is work. To perform their many tasks, cells require transfusions of energy from outside sources. In most ecosystems, energy enters as sunlight. Light
23 Answers and Solutions to Text Problems 23.1 The digestion of polysaccharides takes place in stage 1. 23.2 In stage 3, small molecules are converted to CO 2, H 2 O, and energy for ATP synthesis. 23.3
Introduction to Biology Respiration Chapter 8 Introduction Being alive is work. Cells organize small organic molecules into polymers such as the proteins, carbohydrates, and so forth you studied last week.
Amphibolic nature of Krebs Cycle How what we are is what we eat In aerobic organisms, the citric acid cycle is an amphibolic pathway, one that serves in both catabolic and anabolic processes. Since the
Chapter 9 Cellular Respiration: Harvesting Chemical Energy Lecture Outline Overview: Life Is Work To perform their many tasks, living cells require energy from outside sources. Energy enters most ecosystems
23.2 Glucose Metabolism: An Overview When glucose enters a cell from the bloodstream, it is immediately converted to glucose 6- phosphate. Once this phosphate is formed, glucose is trapped within the cell
Section: 3.4 Name: Opening Activity: What is the equation for photosynthesis? Latin Root Word: Review of Old Information: Review of Old Information: 1. All energy begins as what type of energy and from
AP Bio Photosynthesis & Respiration Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. What is the term used for the metabolic pathway in which
Unit 3 Lecture METABOLISM Anabolism is defined as the chemical reactions that combine simple substances into more complex molecules (requires energy). Examples of anabolism include glycogenesis (conversion
Chapter 9 CELLULAR RESPIRATION HARVESTING FREE ENERGY Photosynthesis takes free energy and puts it into carbohydrates/sugars Carbohydrates can be stored for later use; light can not and neither can ATP
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