Physio Exam 1
As a result of low plasma glucose concentrations, the activity of which of the following metabolic pathways would be elevated? a) Glycogenolysis and lipolysis b) Lipogenesis and glycogenesis c) Gluconeogenesis and lipogenesis d) Glycogenolysis and glycogenesis e) Lipolysis and glycogenesis
a) Glycogenolysis and lipolysis
Cyanide is a poison that prevents oxygen from accepting electrons from the electron transport chain. If cyanide were added to cells, which of the following would cease? a) Oxidative phosphorylation and the Krebs cycle b) The Krebs Cycle c) Oxidative phosphorylation d) ATP synthesis e) glycolysis
a) Oxidative phosphorylation and the Krebs cycle Cyanide prevents oxygen from accepting the low-energy electrons from the electron transport chain. Therefore, no additional high-energy electrons (from NADH or FADH2) can be added to the chain. This leads to the shut-down of the electron transport chain. Due to the relationship between then the Krebs cycle and the electron transport chain, the Krebs cycle would also cease. Glycolysis can continue to produce ATP; the conversion of pyruvate to lactate regenerates enough NAD+ to keep glycolysis running. However, most organisms will not survive on only 2 ATP produced per glucose molecule oxidized.
As glucose is oxidized, how many times will the Krebs (citric acid) cycle turn, and how much NADH, FADH2 and ATP is produced during this process? a) The Krebs (citric acid) cycle turns twice and 6 NADH, 2 FADH2 and 2 ATP are produced as a result of oxidizing glucose. b) The Krebs (citric acid) cycle turns once and 3 NADH, 1 FADH2 and 1 ATP are produced as a result of oxidizing glucose. c) The Krebs (citric acid) cycle turns twice and 3 NADH, 1 FADH2 and 1 ATP are produced as a result of oxidizing glucose. d) The Krebs (citric acid) cycle turns once and 6 NADH, 2 FADH2 and 2 ATP are produced as a result of oxidizing glucose.
a) The Krebs (citric acid) cycle turns twice and 6 NADH, 2 FADH2 and 2 ATP are produced as a result of oxidizing glucose. The oxidation of glucose in glycolysis yields two pyruvate molecules. Next, each pyruvate molecule is oxidized to acetyl-CoA. Hence, in order to harvest the energy from glucose, the Krebs (citric acid) cycle must turn twice to oxidize the two acetyl-CoA molecules. Each turn of the cycle yields 3 NADH, 1 FADH2 and 1 ATP. Two turns of the Krebs (citric acid) cycle yield 6 NADH, 2 FADH2 and 2 ATP.
Within the mitochondria, __________. a) the energy contained in the hydrogen ion gradient is used to synthesize ATP b) the source of electrons for the electron transport chain is pyruvate c) energy from the electron transport chain is used to move hydrogen ions down their concentration gradient d) the final electron acceptor in the electron transport chain is carbon dioxide
a) the energy contained in the hydrogen ion gradient is used to synthesize ATP
In glycolysis, __________. a) two molecules of pyruvate are produced from each molecule of glucose b) oxygen is consumed c) carbon dioxide is produced
a) two molecules of pyruvate are produced from each molecule of glucose Two molecules of pyruvate are produced from each molecule of glucose is correct. Glycolysis is the first step in the process of oxidizing glucose and occurs independently of oxygen. The six-carbon glucose molecule is broken in half, producing two three-carbon pyruvate molecules, which will enter the mitochondria. No carbon dioxide is produced during this process. Oxygen is consumed during oxidative phosphorylation (and the electron transport chain). Carbon dioxide is produced during the process of oxidizing pyruvate to acetyl-CoA (link step) and the Krebs (citric acid) cycle. None is produced during glycolysis. Two molecules of pyruvate are produced during glycolysis as a result of oxidizing glucose.
Increasing muscle mass and decreasing fat content in your body can increase resting metabolism. Which feature below most likely contributes to this? a) Fat cells have no blood supply and cannot carry nutrients to be metabolized. b) Muscle cells have more mitochondria than fat cells which allows for more energy to be released from sugar. c) Adipocytes contain more cytoplasmic inclusions, which slow down metabolism. d) Doing so requires exercise,and exercising in turn burns calories.
b) Muscle cells have more mitochondria than fat cells which allows for more energy to be released from sugar. In fact, it is relatively easy to say that a cell whose job it is to store energy would have a well-designed means for distributing the energy it stores when called for, but would be especially efficient and frugal when it came to utilizing the stored energy for its own purposes of survival. Mitochondria utilize sugar in the making of ATP and can turn to stored fat as a source of that sugar in adipose cells. Mitochondria are also many times more numerous in skeletal muscle cells. If one decreases the amount of fat stored in adipocytes and also reduces consumption of dietary items that could be converted to fats to replace that use, it follows that the metabolic rate at rest would rise to utilize the calories provided more efficiently and to then burn those calories from sugars in the diet more efficiently. The other choices are simply factually incorrect.
What is the purpose of the conversion of pyruvate to lactate? a) ATP is produced to meet the energy requirements of the cell. b) NAD+ is regenerated and permits glycolysis to continue. c) Lactate is produced and shuttled to oxidative phosphorylation in the mitochondria to harvest the energy from the molecule. d) NADH is generated and shuttled to oxidative phosphorylation in the mitochondria to harvest the energy from the molecule. e) Lactate is produced, which permits glycolysis to continue.
b) NAD+ is regenerated and permits glycolysis to continue. During the conversion of pyruvate to lactate, NAD+ is regenerated and permits glycolysis to continue during low oxygen conditions. This permits the continued operation of glycolysis and ATP production. Lactate is then utilized in the process of gluconeogenesis, not oxidative phosphorylation.
Each turn of the Krebs (citric acid) cycle produces __________. a) FAD b) NADH c) four ATP molecules by substrate phosphorylation d) no carbon dioxide molecules
b) NADH Each turn of the Krebs (citric acid) cycle produces NADH. Specifically, three NADH are produced as a result of oxidizing acetyl-CoA. The first molecule of NADH is produced during the oxidation of isocitrate to α-ketoglutarate. The second NADH is a product of oxidizing α-ketoglutarate to succinyl-CoA. The third NADH is a product of the oxidation of fumarate to oxaloacetate. FAD is reduced to FADH2 as a result of oxidizing succinate to fumarate in the Krebs (citric acid) cycle. One molecule of ATP is produced as a result of substrate phosphorylation during the Krebs (citric acid) cycle. The phosphate atom was transferred from GTP to ADP forming ATP. During the Krebs (citric acid) cycle, carbon-carbon bonds are broken twice, yielding two molecules of CO2.
The fatty acids released from the breakdown of lipids are converted by beta oxidation into __________ molecules. a) pyruvate b) acetyl CoA c) glucose d) glycerol
b) acetyl CoA The fatty acids released from the breakdown of lipids are converted by beta oxidation into acetyl-CoA molecules. Beta oxidation is the process of catabolizing fatty acids to acetyl-CoA, and this process occurs in the mitochondrial matrix. The rate of beta oxidation increases in times of fasting or when other energy supplies are running low. The hydrolysis of triglycerides produces glycerol and free fatty acids. Glycerol would not be produced during beta oxidation. Glycogenolysis and gluconeogenesis produce glucose, but beta oxidation does not. Pyruvate is the product of glycolysis, not beta oxidation.
CO2 is produced during __________. a) conversion of pyruvate to lactate b) the Krebs (citric acid) cycle c) glycolysis d) oxidative phosphorylation
b) the Krebs (citric acid) cycle During the Krebs (citric acid) cycle, carbon-carbon bonds are broken twice yielding two molecules of CO2. The first molecule of CO2 is produced from oxidizing isocitrate to α-ketoglutarate. The second CO2 molecule is a product of the oxidation of α-ketoglutarate to succinyl-CoA. No CO2 is produced during glycolysis; ATP, NADH, and pyruvate are the products of glycolysis. No CO2 is produced during oxidative phosphorylation; NAD+, FAD, ATP, and water are products of oxidative phosphorylation. No CO2 is produced during the conversion of pyruvate to lactate; NAD+ and lactate are the products of this process.
The majority of the time the human body utilizes aerobic cellular respiration to meet its energy needs as opposed to anaerobic cellular respiration. Why? a) Anaerobic cellular respiration requires oxygen in order to oxidize glucose. During times of low oxygen, anaerobic cellular respiration ceases while aerobic cellular respiration will continue. b) As a result of oxidizing one glucose molecule, the ATP yield is greater from aerobic cellular respiration than anaerobic cellular respiration. c) Aerobic cellular respiration occurs in the cytosol of the cell, whereas anaerobic cellular respiration occurs in the mitochondria. Thus, the cell works harder to shuttle molecules in and out of organelles in order to complete anaerobic cellular respiration. d) Aerobic cellular respiration is a shorter process; hence, less time is required to produce ATP from this process.
c) As a result of oxidizing one glucose molecule, the ATP yield is greater from aerobic cellular respiration than anaerobic cellular respiration. During aerobic cellular respiration, the energy harvested from the oxidation of glucose is efficiently utilized to produce optimal quantities of ATP in order to meet the needs of the cell. Specifically, anaerobic cellular respiration produces 2 ATP per glucose molecule while aerobic cellular respiration produces more than 30 ATP molecules per glucose molecule. Aerobic cellular respiration is a longer process than anaerobic cellular respiration. The majority of aerobic cellular respiration occurs in the mitochondria (except for glycolysis), while anaerobic cellular respiration occurs in the cytosol. Anaerobic refers to "a lack of oxygen." Thus, oxygen is not required for anaerobic cellular respiration to occur, while it is mandatory for aerobic cellular respiration.
During a fast, the rate(s) of which of the following reactions may increase? a) Glycogenesis b) Glycogenesis and lipogenesis c) Gluconeogenesis and glycogenolysis d) Gluconeogenesis e) Lipogenesis f) Glycogenolysis
c) Gluconeogenesis and glycogenolysis During a fast, blood glucose concentrations need to be maintained. Gluconeogenesis is the process by which lactate, amino acids, and glycerol are used to produce glucose in the liver. Glycogenolysis is the process by which glycogen is hydrolyzed in order to produce glucose. The glucose produced from both processes is released into the blood to compensate for the fast. Glycogenesis is the process of producing glycogen from glucose molecules, and it occurs in the liver and skeletal muscle. During a fast, blood glucose needs to be maintained. If the rate of glycogenesis increased, the blood glucose concentration decreases. During fasting, the body needs to perform metabolic processes that increase the blood glucose concentration. During a fast, blood glucose concentrations need to be maintained. Gluconeogenesis is the process by which lactate, amino acids, and glycerol are used to produce glucose in the liver. The glucose is then released into the blood, resulting in an increase in blood glucose concentrations. Thus, the rate of gluconeogenesis should increase during fasting. There is another process that also elevates blood glucose concentrations. During a fast, blood glucose concentrations need to be maintained. Glycogenolysis is the process by which glycogen is hydrolyzed in order to produce glucose, which is released into the blood. The rate of glycogenolysis should increase in a fasting state. There is another process that also elevates blood glucose concentrations. Lipogenesis is the production of fatty acids from acetyl-CoA. The rate of lipogenesis increases during time of excess consumption of nonlipid food such as carbohydrates and proteins. Hence, during a fast, the rate of lipogenesis would decrease. During a fast, blood glucose concentrations need to be maintained. Lipogenesis is the process of producing lipids from nonlipid substrates such as carbohydrates and proteins. If the rate of lipogenesis increased, then blood glucose concentrations would decrease during a fast. Thus, we would expect to see the rate of lipogenesis decrease during a fast.
Which of the following occur in the mitochondria? a) Glycolysis b) Krebs cycle c) Krebs cycle and oxidative phosphorylation d) Oxidative phosphorylation
c) Krebs cycle and oxidative phosphorylation The Krebs cycle occurs in the mitochondrial matrix. Oxidative phosphorylation also occurs inside the mitochondria, across the mitochondrial inner membrane. However, glycolysis occurs in the cytoplasm.
During the oxidation of glucose, which of the following reactions ultimately produces the greatest number of ATP molecules? a) All of the reactions involved in the oxidation of glucose produce the same number of ATP molecules. b) Krebs cycle c) Oxidative phosphorylation d) Glycolysis
c) Oxidative phosphorylation As a result of oxidizing glucose, oxidative phosphorylation produces the greatest number of ATP molecules during the oxidation of NADH and FADH2. Using the energy from the high energy electrons from NADH and FADH2, hydrogen ions are pumped against their concentration gradient into the inner membrane space. Utilizing the energy from hydrogen ions moving down their concentration gradient across the inner membrane mitochondrial membrane through ATP synthase produces ATP. Hence, 10 NADH and 2 FADH2 are the energy products from glycolysis, oxidizing pyruvate and the Krebs cycle (citric acid cycle). These molecules are shuttled to oxidative phosphorylation to convert the energy in NADH and FADH2 to ATP. Approximately 3 ATP are produced from the energy stored in 1 NADH molecule while approximately 2 ATP are produced from the energy stored in 1 FADH2. Hence, more than 30 ATP are produced during oxidative phosphorylation, more than any other metabolic processes in aerobic cellular respiration.
What is the main purpose of oxidative phosphorylation? a) The energy produced from pumping hydrogen ions up their concentration gradient is provided by ATP synthase and produces water to maintain hydration in the cell. b) ATP synthase provides the energy to pump hydrogen ions across the inner mitochondrial membrane up their concentration gradient to synthesize ATP to meet the energy needs of the cell. c) The energy stored in NADH and FADH2 is utilized to produce ATP to meet the energy needs of the cell. d) The energy in NADH and FADH2 is used to produce water to maintain the appropriate water concentration in the intracellular fluid. e) The energy in ATP is used during oxidative phosphorylation to produce NAD+ and FAD, all of which are reactants for glycolysis, the oxidation of pyruvate, and the Krebs (citric acid) cycle which allows these processes to continue without interruption.
c) The energy stored in NADH and FADH2 is utilized to produce ATP to meet the energy needs of the cell. The energy in NADH and FADH2 is utilized in oxidative phosphorylation (and the electron transport chain) to produce ATP. Specifically, the oxidation of NADH and FADH2 provides high-energy electrons to the electron transport chain; the chain utilizes the energy in these electrons to pump hydrogen ions across the inner mitochondrial membrane against their concentration gradient. The hydrogen ions move back across the mitochondrial membrane down their concentration gradient by traveling through ATP synthase, which utilizes the energy from the gradient to phosphorylate ADP producing ATP. Water is produced as the electrons are picked up by oxygen from the electron transport chain; however, maintaining the appropriate water concentration in the intracellular fluid is not the main purpose of the electron transport chain. ATP is a product of the oxidative phosphorylation, not a reactant. Moreover, NAD+ and FAD are produced as a result of oxidizing NADH and FADH2; ATP is not involved in this process. ATP synthase is an enzyme and cannot provide energy for a reaction.
During the hydrolysis of proteins (proteolysis), the deamination process produces __________. a) amino acids b) urea c) ammonia d) glucose
c) ammonia Deamination is the process of producing an ammonia molecule and organic acid from amino acids. Examples of organic acids are pyruvate, acetyl-CoA, or intermediates from the Krebs (citric acid) cycle, and these molecules will enter the aerobic metabolism pathway in order to harvest the energy from them. Since ammonia is a toxic molecule, it travels via the blood to the liver and is converted to urea and excreted in the urine. Urea is produced in the liver from ammonia; deamination does not produce urea. Amino acids are the reactants for deamination, not the products. Gluconeogenesis utilizes amino acids to produce glucose; glucose is not a product of deamination.
Anabolic reactions __________. a) occur spontaneously in the forward direction b) occur in the reverse direction when coupled to catabolic reactions c) occur in the forward direction when they are part of a metabolic pathway that has a net energy change that is negative d) All of the listed responses are correct.
c) occur in the forward direction when they are part of a metabolic pathway that has a net energy change that is negative Anabolic reactions involve the production of larger molecules from smaller reactants. For an anabolic reaction to have a net energy change that is negative, the reaction is coupled to a catabolic reaction in the metabolic pathway; the catabolic reaction provides the required energy in order for the anabolic reaction to proceed forward. Anabolic reactions involve the production of larger molecules from smaller reactants, which requires the input of energy and are often endergonic reactions. For an anabolic reaction to occur in the reverse direction, the resultant reaction would be catabolic. Two catabolic reactions are never coupled to each other. Reactions occur spontaneously in the forward direction when they release energy (that is, exergonic reaction). Anabolic reactions involve the production of larger molecules from smaller reactants, which requires the input of energy and would qualify as an endergonic reaction.
Glucose oxidation cannot proceed beyond glycolysis unless __________. a) pyruvate is converted to lactate b) acetyl-CoA enters the mitochondria c) oxygen is present
c) oxygen is present Oxygen is needed for glucose oxidation to proceed beyond glycolysis to the oxidation of pyruvate to acetyl-CoA, the Krebs cycle, and oxidative phosphorylation. Specifically, oxygen is a reactant of oxidative phosphorylation. Important products of oxidative phosphorylation are NAD+and FAD, which are reactants of the Krebs cycle (citric acid cycle), oxidation of pyruvate to acetyl-CoA, and glycolysis. Without oxygen, oxidative phosphorylation ceases. As a result, the cell begins to accumulate NADH and FADH2. Decreased amounts of NAD+ and FAD are available to the cell, which causes the process of oxidizing pyruvate to acetyl-CoA and the Krebs cycle (citric acid cycle) to cease. Acetyl-CoA is produced in the mitochondria. It does not influence the continuation of glucose oxidation. The production of lactate from pyruvate is a result of anaerobic cellular respiration. This reaction occurs during time of low oxygen.
Which of the following types of chemical reactions occur in glycolysis? a) Phosphorylation b) Reduction c) Oxidation d) All of the listed responses are correct
d) All of the listed responses are correct All of the given reactions occur during glycolysis. Specifically, glucose is oxidized and 2 NAD+ molecules are reduced to NADH. In addition, glucose oxidation provides the energy for the phosphorylation of ADP to ATP during glycolysis. Glucose is oxidized during glycolysis. However, oxidation is the process of losing electrons and is coupled to another reaction in order for a molecule to accept the electrons. ATP is phosphorylated during glycolysis, but other energy-carrying molecules are also produced during glycolysis. Reduction occurs during glycolysis. However, reduction is the process of gaining electrons and is coupled to another reaction because a molecule has to donate electrons in the first place.
The reaction, ADP + Pi + energy → ATP + H2O, is an example of __________. a) a condensation reaction b) an endergonic reaction c) oxidative phosphorylation d) All of the listed responses are correct.
d) All of the listed responses are correct The reaction, ADP + Pi + energy → ATP + H2O, is an example of a condensation reaction, oxidative phosphorylation, and an endergonic reaction. In oxidative phosphorylation, ADP binds with free inorganic phosphate (Pi) to form ATP. This is an example of an endergonic reaction in which energy is input into the reaction in order to convert low, smaller energy reactants to large, high-energy products. Condensation is the joining of two or more smaller molecules to form a larger one, and water is generated as a product. Forming a bond between smaller molecules such as ADP and Pi to produce a larger molecule such as ATP meets the definition of condensation. The production of water is another clue that condensation has occurred. In oxidative phosphorylation, ADP binds with free Pi to form ATP. In an endergonic reaction, energy is input into the reaction in order to convert smaller, low energy reactants to large, high-energy products.
In gluconeogenesis, glucose can be synthesized using __________. a) glycerol from triglycerides b) amino acids from proteins c) pyruvate, produced from lactate d) All of the listed responses are correct.
d) All of the listed responses are correct. All of the listed responses are correct. In gluconeogenesis, glucose can be synthesized using amino acids from proteins, glycerol from triglycerides, and pyruvate produced from lactate. In the liver, gluconeogenesis utilizes three reactants in order to produce glucose. Amino acids from proteins, glycerol from triglycerides, and pyruvate produced from lactate are used to produce glucose. Since the nervous system is dependent on the blood for glucose, it is imperative that blood glucose concentrations remain constant. The rate of gluconeogenesis is elevated during times of excessive fasting in order to compensate for the drop in blood glucose levels observed during this activity. The liver utilizes amino acids to produce glucose in gluconeogenesis. However, there are other reactants for gluconeogenesis. The liver utilizes glycerol to produce glucose in gluconeogenesis. However, there are other reactants for gluconeogenesis. The liver utilizes pyruvate to produce glucose during gluconeogenesis. The origin of the pyruvate is lactate produced in skeletal muscle and shuttled to the liver. However, there are other reactants for gluconeogenesis.
When molecules of ATP are broken down into ADP and inorganic phosphate (Pi), and the energy from this reaction is used to power cellular functions, __________. a) the reaction runs spontaneously in the forward direction b) the First Law of Thermodynamics applies c) potential energy is converted into kinetic energy d) All of the listed responses are correct.
d) All of the listed responses are correct. All of the listed responses are correct. When molecules of ATP are broken down into ADP and inorganic phosphate (Pi), and the energy from this reaction is used to power cellular functions, the First Law of Thermodynamics applies, potential energy is converted into kinetic energy, and the reaction runs spontaneously in the forward direction. The First Law of Thermodynamics states that energy cannot be created nor destroyed. Thus, potential and kinetic energy are interchangeable, but the total energy in the system does not change. The conversion of ATP to ADP and inorganic phosphate to fuel cellular activities reflects the change of chemical potential energy to kinetic energy, while the energy of the system remains constant. An additional answer is also correct. ATP possesses chemical potential energy. As a result of the hydrolysis of ATP, the chemical potential energy is converted to kinetic energy, which can be used by the cell to perform work. An additional answer is also correct. The hydrolysis of ATP to ADP and inorganic phosphate is an example of an exergonic reaction which proceeds spontaneously in a forward direction. The reason is exergonic reactions release energy as a result of converting high potential energy reactants (ATP) to low potential energy products (ADP and inorganic phosphate). An additional answer is also correct.
Which of the following is needed in order to couple electron transport to ATP synthesis? a) A proton channel in the inner mitochondrial membrane b) The enzyme ATP phosphatase c) More hydrogen atoms inside the mitochondria than outside d) None of the above
d) None of the above Oxidative phosphorylation consists of two processes that are required for ATP to be produced. First, the electron transport chain pumps H+ up their concentration gradient across the inner mitochondrial membrane via proton pumps. The energy to transport the H+ against their gradient is provided by the electrons that move along the electron transport chain. The second process is the production of ATP by ATP synthase. ATP synthase couples the two processes by allowing H+ to move down its concentration gradient through ATP synthase. ATP synthase transfers the energy from the concentration gradient to a high-energy phosphate bond, forming ATP. Hydrogen atoms are attached to a variety of molecules inside and outside the mitochondria. The number of hydrogen atoms present inside vs. outside the mitochondria would not influence the coupling of electron transport to the production of ATP. ATP phosphatase removes phosphates. In order to produce ATP, a phosphate needs to be added to ADP. The presence of the proton channel permits the transport of H+ against their concentration gradient utilizing the energy from electrons moving through the electron transport chain. However, the proton channel does not couple the electron transport chain with ATP production.
Which of the following is needed in order to couple electron transport to ATP synthesis? a) A proton channel in the inner mitochondrial membrane b) More hydrogen atoms inside the mitochondria than outside c) The enzyme ATP phosphatase d) None of the listed responses is correct.
d) None of the listed responses is correct. Oxidative phosphorylation consists of two processes that are required for ATP to be produced. First, the electron transport chain pumps H+ up their concentration gradient across the inner mitochondrial membrane via proton pumps. The energy to transport the H+ against their gradient is provided by the electrons that move along the electron transport chain. The second process is the production of ATP by ATP synthase. ATP synthase couples the two processes by allowing H+ to move down its concentration gradient through ATP synthase. ATP synthase transfers the energy from the concentration gradient to a high-energy phosphate bond, forming ATP. Hydrogen atoms are attached to a variety of molecules inside and outside the mitochondria. The number of hydrogen atoms present inside vs. outside the mitochondria would not influence the coupling of electron transport to the production of ATP. ATP phosphatase removes phosphates. In order to produce ATP, a phosphate needs to be added to ADP. The presence of the proton channel permits the transport of H+ against their concentration gradient utilizing the energy from electrons moving through the electron transport chain. However, the proton channel does not couple the electron transport chain with ATP production.
The words "fat free" are found on some candy packaging indicating that the candy is made of carbohydrates, not lipids. If individuals incorporate such candy into a diet plan, they will not lose weight, and they might even gain weight. Which of the following statements about how cells regulate their metabolic pathways is true? a) The body converts any excess carbohydrates to proteins in the process of protein synthesis, which could prevent weight loss. b) The body converts any excess carbohydrate to nucleic acids, which could prevent weight loss. c) Any excess carbohydrate consumed is metabolized during aerobic cellular respiration, resulting in excess ATP production and the prevention of weight loss. d) The body converts any excess carbohydrates to lipids in the lipogenesis process, preventing weight loss.
d) The body converts any excess carbohydrates to lipids in the lipogenesis process, preventing weight loss. The body is efficient in its handling of the various macromolecules made available to it through the process of eating. In the liver, lipogenesis utilizes nonlipid foods to produce triglycerides. Thus, weight loss can be prevented if one consumes excess carbohydrates or protein. The body converts any excess carbohydrate, not proteins, to lipids during lipogenesis. There is a fine balance between ATP production and utilization. Excess energy is not stored in the form of ATP; the body uses another molecule to store excess energy. Nucleic acids are synthesized using nucleotides; excess carbohydrate consumption would not result in nucleic acid production.
In the absence of oxygen, the concentration of which of the following increases? a) NADH b) ADP c) Lactate d) FADH2 e) All of the above
e) All of the above
Complete the following pathway: ATP production starts with glucose entering the __________ pathway, which converts a molecule of glucose into __________. Once the final product of glycolysis is made, it enters into the __________ and is converted to __________. This molecule combines with oxalacetate in the __________ pathway, which produces more ATP and high-energy electrons. These high-energy electrons then enter the __________.
glycolysis; pyruvate; mitochondria; acetyl CoA; Krebs (citric acid) cycle; electron transport system ATP production starts with glucose entering the glycolysis pathway, which converts a molecule of glucose into pyruvate. Once the final product of glycolysis is made, it enters into the mitochondria and is converted to acetyl CoA. This molecule combines with oxalacetate in the Krebs (citric acid) cycle pathway, which produces more ATP and high-energy electrons. These high-energy electrons then enter the electron transport system. Glycolysis produces ATP and two pyruvate molecules from glucose; this process occurs in the cytoplasm. Each pyruvate enters the mitochondria and is oxidized resulting in the production of acetyl-CoA. This molecule enters the Krebs (citric acid) cycle and combines with oxaloacetate. One turn of the Krebs (citric acid) cycle produces high energy electrons which combine with 3 NAD+, 1 FAD and 1 ADP and 1 Pi, yielding 3 NADH, 1 FADH2, and 1 ATP. The 3 NADH and 1 FADH2 enter oxidative phosphorylation and the electron transport chain in order to harvest the energy stored in these molecules to produce additional ATP. A product of glycolysis is pyruvate, not glycogen. Pyruvate enters the mitochondria and is used to produce acetyl-CoA. Pyruvate is not converted to oxaloacetate in the cytoplasm; pyruvate is converted to acetyl-CoA in the mitochondria. In addition, high-energy electrons enter the electron transport chain, not the Krebs (citric acid) cycle. Glucose is a product of gluconeogenesis, not a reactant of this process. In addition, pyruvate enters the mitochondria rather than the cytoplasm and is converted to acetyl-CoA rather than oxaloacetate. In addition, high-energy electrons enter the electron transport chain, not the Krebs (citric acid) cycle. Glucose is a product of gluconeogenesis, not glycogen.
