What processes are included in glucose metabolism?
Digestion, absorption, glycolysis, TCA cycle, ETC, and gluconeogenesis.
p.2
Hormonal Regulation of Metabolism
What regulates glucose synthesis and breakdown?
Hormonal and metabolic signals.
What effect does high muscle glycogen level have on exercise?
It allows exercise to continue longer at a submaximal workload.
What is the limitation of stamina for endurance runners associated with?
The depletion of glycogen in muscle and hepatic stores.
p.91
Metabolic Disorders Related to Carbohydrate Consumption
What is the volume and page range of the study by Stanhope et al. (2009)?
Volume 119, pages 1322 - 1334.
p.71
Hormonal Regulation of Metabolism
How does the decrease in insulin affect the liver's role in glucose production?
It promotes gluconeogenesis and glycogenolysis, making the liver a net producer of glucose.
What is gluconeogenesis?
The metabolic process of synthesizing glucose from non-carbohydrate precursors.
p.78
Fatty Acid Synthesis and Breakdown
How are free fatty acids transported in the bloodstream?
They bind to plasma albumin.
p.88
Metabolic Disorders Related to Carbohydrate Consumption
What can long-term consumption of fructose or sucrose lead to?
A number of health problems.
p.17
Hormonal Regulation of Metabolism
What are the opposing hormones that regulate blood glucose levels?
Insulin and glucagon, plus epinephrine.
p.92
Metabolic Disorders Related to Carbohydrate Consumption
How does sugar in soft drinks affect health?
Excessive sugar consumption can lead to metabolic disorders such as obesity and diabetes.
What is the primary focus of a ketogenic diet?
To limit carbohydrate intake.
p.96
Metabolic Disorders Related to Carbohydrate Consumption
How does acetaldehyde affect proteins?
It attaches covalently to proteins to form protein adducts, changing their activity.
In what type of exercise does high muscle glycogen not apply?
Low levels of exercise or high-level exercise for short periods.
p.14
Hormonal Regulation of Metabolism
In which tissues does insulin primarily act?
Liver, muscle, and adipose tissues.
p.84
Fructose and Ethanol Metabolism
What is the first step in fructose metabolism?
Fructose is phosphorylated to fructose-1-phosphate by fructokinase.
p.4
Metabolic Disorders Related to Carbohydrate Consumption
What is the likelihood of carbohydrate deficiency in food?
The chance of carbohydrate deficiency is low.
p.7
Hormonal Regulation of Metabolism
What does intermediary metabolism encompass?
All reactions concerned with storing and generating metabolic energy and using that energy in biosynthesis.
p.90
Hormonal Regulation of Metabolism
How does excess lipid in the liver affect insulin signaling?
It interrupts insulin-induced signaling, leading to insulin resistance.
p.54
Tricarboxylic Acid (TCA) Cycle
What is the role of NADH in the regulation of the TCA cycle?
NADH acts as an indicator of the energy status of the cell, inhibiting the cycle when levels are high.
p.42
Hormonal Regulation of Metabolism
What is the effect of elevated glucagon on fructose 2,6-bisphosphate levels in the liver?
Elevated glucagon decreases the intracellular concentration of fructose 2,6-bisphosphate.
p.54
Tricarboxylic Acid (TCA) Cycle
How does ATP influence the TCA cycle?
High ATP levels inhibit the cycle, signaling sufficient energy availability.
What happens to the energy produced from fatty acid oxidation in relation to gluconeogenesis?
The energy produced is used to drive gluconeogenesis, ensuring that glucose can be synthesized from other substrates.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is oxidative phosphorylation?
The process of ATP production that occurs in the mitochondria, driven by the electron transport chain.
What is the Cori Cycle?
The process where lactate is converted back to glucose in the liver.
What is gluconeogenesis?
The synthesis of glucose from non-carbohydrate precursors.
p.16
Hormonal Regulation of Metabolism
What type of receptor does glucagon bind to?
Glucagon receptor, which is a G protein-coupled receptor.
p.81
Hormonal Regulation of Metabolism
How would an adipocyte’s response to epinephrine be affected by an inhibitor of cAMP phosphodiesterase (PDE)?
The inhibitor would prevent the breakdown of cAMP, leading to prolonged activation of protein kinase A (PKA) and enhanced lipolysis in adipocytes.
p.51
Hormonal Regulation of Metabolism
What is the function of PDH phosphatase?
It dephosphorylates and activates E1.
Which enzyme complex is responsible for the conversion of pyruvate to acetyl-CoA?
Pyruvate dehydrogenase complex (PDH complex).
p.14
Hormonal Regulation of Metabolism
What is the expression pattern of GLUT2 in the liver?
GLUT2 expression on the cell surface is constant.
p.87
Fructose and Ethanol Metabolism
What does fructokinase convert fructose into?
F1P (fructose-1-phosphate).
p.75
Fatty Acid Synthesis and Breakdown
What causes allosteric activation of ACC?
Citrate causes protomers to polymerize into an active form.
What is a ketogenic diet?
A dietary program that restricts carbohydrate consumption.
What are important non-carbohydrate sources for gluconeogenesis?
Lactate, glycerol, and certain amino acids.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What does ETC stand for?
Electron Transport Chain.
p.76
Fatty Acid Synthesis and Breakdown
What is de novo lipogenesis?
The synthesis of fatty acids (FA) and triacylglycerol (TAG) from substrates other than lipid.
p.31
Hormonal Regulation of Metabolism
What happens to the synthesis of glycolytic enzymes during fasting?
It is decreased due to increased glucagon.
p.42
Hormonal Regulation of Metabolism
What role does fructose 2,6-bisphosphate play in metabolism?
It acts as a regulator of glycolysis and gluconeogenesis.
p.96
Metabolic Disorders Related to Carbohydrate Consumption
What liver condition can result from acetaldehyde interaction?
Liver fibrosis, eventually leading to cirrhosis.
p.51
Hormonal Regulation of Metabolism
What inhibits PDH kinase?
Pyruvate, which keeps E1 active.
p.82
Hormonal Regulation of Metabolism
What factors influence the direction of acyl-CoA metabolism?
The availability of substrates, energy status of the cell, and hormonal regulation influence whether acyl-CoA is directed towards synthesis or oxidation.
What is the relationship between gluconeogenesis and glycolysis?
The signals that inhibit or activate gluconeogenesis have the opposite effect on glycolysis, providing reciprocal control of the pathways.
p.72
Metabolic Disorders Related to Carbohydrate Consumption
Why is hypoglycemia mild in Type VI glycogen storage disease?
In liver glycogen phosphorylase deficiency, glycogen can still be partially broken down, allowing for some glucose release, resulting in less severe hypoglycemia.
p.65
Hormonal Regulation of Metabolism
What is activated by the binding of glucagon or epinephrine?
Adenylyl cyclase, leading to the synthesis of cAMP.
p.15
Hormonal Regulation of Metabolism
What hormones oppose the actions of insulin?
Glucagon, epinephrine, and growth hormone.
Why is lactate released into the blood?
To regenerate NAD+ during anaerobic glycolysis in exercising skeletal muscle and RBCs.
What role does glucose 6-phosphatase play in glycogen metabolism?
It converts glucose 6-phosphate into free glucose, which is essential for maintaining blood sugar levels.
What role does NAD+ play in glycolysis?
It acts as an electron carrier, being reduced to NADH.
What metabolic state is indicated by elevated levels of acetyl-CoA?
Increased synthesis of oxaloacetate (OAA), e.g., during fasting.
p.90
Metabolic Disorders Related to Carbohydrate Consumption
What is chronic fructose consumption highly associated with?
The risk of diabetes onset.
p.85
Metabolic Disorders Related to Carbohydrate Consumption
What is the difference between wholefood and processed food?
Wholefood is minimally processed and retains its natural nutrients, while processed food often contains additives and is altered from its original form.
p.90
Fatty Acid Synthesis and Breakdown
What is the metabolic pathway for fructose in the liver?
Fructose → F1P → acetyl-CoA → TAG.
p.31
Hormonal Regulation of Metabolism
Which key glycolytic enzymes are affected by insulin in the liver?
GK (Glucokinase), PFK-1 (Phosphofructokinase-1), and PK (Pyruvate Kinase).
What role does fatty acid oxidation play in gluconeogenesis?
Fatty acid oxidation provides energy and metabolic intermediates that support gluconeogenesis, even though acetyl-CoA cannot be directly converted into glucose.
What is G1P converted to during glycogenolysis?
G6P (glucose-6-phosphate).
Which substrates are commonly used in gluconeogenesis?
Lactate, glycerol, and amino acids.
p.80
Fatty Acid Synthesis and Breakdown
What is the main purpose of fatty acid degradation?
To break down fatty acids for energy production.
p.15
Hormonal Regulation of Metabolism
What is glucagon?
A peptide hormone produced by α-cells of the pancreas.
p.89
Metabolic Disorders Related to Carbohydrate Consumption
What does chronic fructose consumption lead to in the liver?
Lipid accumulation and hyperlipidemia.
p.74
Fatty Acid Synthesis and Breakdown
What is the rate-limiting step in fatty acid synthesis?
Carboxylation of acetyl-CoA to malonyl-CoA by acetyl-CoA carboxylase (ACC).
p.33
Hormonal Regulation of Metabolism
What is the activity level of PFK-1 in an individual who consumed a carbohydrate-rich meal about an hour ago?
The activity level of PFK-1 is high due to increased levels of fructose-2,6-bisphosphate.
What is the first step of gluconeogenesis?
The conversion of pyruvate to PEP via OAA.
p.57
Hormonal Regulation of Metabolism
Where is uncoupling protein 1 (UCP1) expressed?
Only in brown adipose tissue.
p.52
Tricarboxylic Acid (TCA) Cycle
What do NADH and FADH2 do in the TCA cycle?
They pass high-energy electrons to the Electron Transport Chain (ETC) for ATP synthesis.
What is the central role of glucose metabolism?
It is central to energy homeostasis.
p.91
Metabolic Disorders Related to Carbohydrate Consumption
In which journal was the study on chronic fructose consumption published?
Journal of Clinical Investigation.
p.85
Carbohydrate Digestion and Absorption
What type of food is high in lactose?
Dairy products such as milk and cheese.
p.51
Hormonal Regulation of Metabolism
What is the role of PDH kinase in the PDH complex?
It phosphorylates and inactivates E1.
p.7
Hormonal Regulation of Metabolism
What are important reactions of intermediary metabolism focused on?
Storing and generating metabolic energy.
What is the overall reaction of glycolysis?
Glucose + 2NAD + 2ADP + 2P_i → 2 pyruvate + 2NADH + 2H + 2ATP + 2H2O.
p.98
Carbohydrate Digestion and Absorption
How do we digest and absorb carbohydrates?
Through enzymatic breakdown in the digestive system, followed by absorption in the intestines.
p.42
Hormonal Regulation of Metabolism
How does glucagon influence gluconeogenesis in the liver?
By decreasing fructose 2,6-bisphosphate, glucagon promotes gluconeogenesis.
p.13
Hormonal Regulation of Metabolism
What stimulates the secretion of insulin?
Glucose, amino acids, and gastrointestinal peptide hormones.
p.30
Hormonal Regulation of Metabolism
What activates Pyruvate Kinase (PK)?
F1,6-BisP (feed-forward activation).
What inhibits fructose 1,6-bisphosphatase?
Elevated levels of AMP and F2,6-bisP.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
How do protons contribute to ATP synthesis in oxidative phosphorylation?
Protons flow back into the mitochondrial matrix through ATP synthase, driving the conversion of ADP to ATP.
p.19
Tricarboxylic Acid (TCA) Cycle
What cycle generates high-energy electrons from glucose?
Tricarboxylic Acid (TCA) Cycle.
What is the significance of a high Vmax for Glucokinase?
It allows the liver to effectively remove large amounts of glucose from portal blood.
p.97
Fatty Acid Synthesis and Breakdown
What enzyme catalyzes the conversion of acetyl-CoA to malonyl-CoA in lipogenesis?
Acetyl-CoA carboxylase (ACC).
p.6
Carbohydrate Digestion and Absorption
How is glucose absorbed in the small intestine?
By carrier-mediated transport via the sodium-glucose co-transporter (SGLT1).
p.17
Hormonal Regulation of Metabolism
How is insulin secretion related to glucagon release?
Insulin secretion is closely coordinated with the release of glucagon.
p.40
Hormonal Regulation of Metabolism
What effect does glucagon have on PEP carboxykinase gene expression?
Glucagon increases the gene expression of PEP carboxykinase.
p.3
Carbohydrate Digestion and Absorption
What are the three main types of carbohydrates mentioned?
Glucose, Fructose, Galactose.
p.6
Carbohydrate Digestion and Absorption
What transporter is responsible for glucose leaving the cells?
Glucose transporter (GLUT2) via facilitated diffusion.
What does uncontrolled gluconeogenesis lead to?
High blood glucose levels.
p.91
Metabolic Disorders Related to Carbohydrate Consumption
What is the main focus of the study by Stanhope et al. (2009)?
Chronic fructose consumption.
p.40
Hormonal Regulation of Metabolism
What effect does insulin have on PEP carboxykinase gene expression?
Insulin decreases the gene expression of PEP carboxykinase.
p.17
Hormonal Regulation of Metabolism
What happens to blood levels of glucose after the ingestion of a carbohydrate-rich meal?
Blood levels of glucose, insulin, and glucagon change significantly.
Where is glycogen mainly stored in the body?
In skeletal muscle and liver.
p.86
Fructose and Ethanol Metabolism
Why do food and soft drink manufacturers prefer fructose?
Because it exerts a significantly increased perception of sweetness.
p.96
Metabolic Disorders Related to Carbohydrate Consumption
What is the toxicity level of acetaldehyde?
High levels of acetaldehyde are toxic.
p.7
Hormonal Regulation of Metabolism
What types of compounds are involved in intermediary metabolism?
Low-molecular-weight compounds and energy storage compounds.
p.71
Hormonal Regulation of Metabolism
What hormonal change occurs between evening meal and breakfast that affects blood glucose levels?
Insulin levels decrease and glucagon levels increase.
p.92
Metabolic Disorders Related to Carbohydrate Consumption
What is the typical sugar content in soft drinks?
Soft drinks often contain high levels of sugar, sometimes exceeding recommended daily limits.
What is the primary function of muscle glycogen?
To serve as a fuel reserve for the synthesis of ATP during muscle contraction.
What does 'hitting the wall' refer to?
A condition of sudden fatigue and loss of energy caused by the depletion of glycogen stores.
p.67
Hormonal Regulation of Metabolism
What is the primary hormonal control of glycogen metabolism?
Insulin and glucagon play key roles in regulating glycogen synthesis and degradation.
How does liver glycogen help maintain blood glucose levels?
By maintaining blood glucose concentration during the early stages of a fast (10 - 18 hours).
p.13
Hormonal Regulation of Metabolism
Where is insulin produced?
In the β-cells of the pancreas.
What is the first step in gluconeogenesis involving pyruvate?
Carboxylation of pyruvate to oxaloacetate (OAA).
p.78
Fatty Acid Synthesis and Breakdown
What must happen to fatty acids before they undergo β-oxidation?
They must be activated to their CoA derivative.
p.20
Hormonal Regulation of Metabolism
What is a characteristic of an insulinoma?
Constant production of insulin by tumor cells.
What is the significance of metabolic intermediates in gluconeogenesis?
Metabolic intermediates from fatty acid oxidation are crucial for gluconeogenesis as they help in the conversion of non-carbohydrate sources into glucose.
How is free glucose released from glycogen?
By glycogen debranching enzyme at the α(1 → 6) linked glucosyl residue.
What is the normal range for glucose homeostasis?
4 – 6 mmol/L (70 – 110 mg/dL).
p.67
Hormonal Regulation of Metabolism
What is the effect of insulin on glycogen synthesis?
Insulin stimulates glycogen synthesis.
What type of bonds are broken to release glucose 1-phosphate?
α(1 → 4) glycosidic bonds.
p.33
Hormonal Regulation of Metabolism
What is the phosphorylation state of PFK-2 after a carbohydrate-rich meal?
PFK-2 is dephosphorylated, which activates it and increases fructose-2,6-bisphosphate levels.
p.80
Hormonal Regulation of Metabolism
What role do hormones play in the regulation of fatty acid metabolism?
Hormones like insulin and glucagon influence the balance between synthesis and degradation.
p.27
Hormonal Regulation of Metabolism
What occurs when blood glucose levels increase?
GK is released by GKRP and re-enters the cytosol for glucose phosphorylation.
p.81
Hormonal Regulation of Metabolism
What effect does epinephrine have on adipocytes?
Epinephrine stimulates lipolysis, leading to the breakdown of stored fats.
p.66
Hormonal Regulation of Metabolism
What is the effect of insulin on glycogen synthase?
It activates glycogen synthase (dephosphorylated) to begin glycogenesis.
What effect does acetyl-CoA have on the PDH complex?
It inhibits the PDH complex by activating PDH kinase.
What is carbohydrate/glycogen loading?
A dietary strategy to maximize glycogen storage in muscle and liver for enhancing endurance performance.
p.18
Hormonal Regulation of Metabolism
What is the primary function of insulin in metabolism?
To lower blood glucose levels by promoting glucose uptake and storage.
p.5
Carbohydrate Digestion and Absorption
What types of carbohydrates are primarily digested?
Starches (plant) and glycogen (animal).
p.18
Hormonal Regulation of Metabolism
What role does glucagon play in metabolism?
To raise blood glucose levels by promoting glycogen breakdown and gluconeogenesis.
p.55
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What are the key components involved in the electron transfer process in the ETC?
Coenzyme Q (CoQ) and cytochrome c (cyt c).
What is the most potent activator of PFK - 1?
Fructose 2,6-bisphosphate (F2,6-bisP).
p.77
Hormonal Regulation of Metabolism
What effect does high plasma insulin levels have on hormone-sensitive lipase (HSL)?
It dephosphorylates and inactivates HSL.
What is the first step of glycolysis?
The phosphorylation of glucose to glucose-6-phosphate.
p.53
Tricarboxylic Acid (TCA) Cycle
What regulates the TCA cycle?
The overall energy status, not a particular substrate.
What is the role of glycogenin in glycogenesis?
Glycogenin serves as the site for the initial glucosyl unit from UDP-glucose.
p.80
Fatty Acid Synthesis and Breakdown
What is the primary function of fatty acid synthesis?
To create fatty acids for energy storage and membrane formation.
p.71
Hormonal Regulation of Metabolism
What metabolic processes are triggered by the hormonal changes during fasting?
Gluconeogenesis and glycogenolysis are triggered to increase blood glucose levels.
p.57
Hormonal Regulation of Metabolism
What is the function of uncoupling protein 1 (UCP1)?
It is a proton translocator that allows H+ to flow back into the matrix, making it unavailable for ATP synthesis.
p.97
Metabolic Disorders Related to Carbohydrate Consumption
How does an increased NADH/NAD+ ratio affect the TCA cycle?
It reduces the TCA cycle activity.
p.57
Hormonal Regulation of Metabolism
What happens to the energy derived from H+ influx in the uncoupling reaction?
It is dissipated as heat, a process known as non-shivering thermogenesis.
p.79
Fatty Acid Synthesis and Breakdown
What is the role of acetyl-CoA produced from β-oxidation?
It can be oxidized or used in hepatic ketogenesis.
p.95
Fructose and Ethanol Metabolism
Where is ethanol absorbed in the body?
In both the stomach and intestine.
What is the final step in the conversion of malate during gluconeogenesis?
Decarboxylation to phosphoenolpyruvate (PEP).
Which tissues require a continuous supply of glucose?
Brain, red blood cells, kidney medulla, lens and cornea of the eye, testes, and exercising muscle.
p.73
Fatty Acid Synthesis and Breakdown
What is the main enzyme involved in fatty acid synthesis?
Acetyl-CoA carboxylase is the key enzyme in fatty acid synthesis.
What is the function of the branching enzyme in glycogenesis?
It removes 6-8 glucosyl residues from the nonreducing end and attaches them to a non-terminal glucosyl residue by an α (1 → 6) linkage.
What is the ATP yield difference between glycolysis and gluconeogenesis?
Glycolysis yields 2 ATP, while gluconeogenesis consumes 6 ATP.
p.29
Hormonal Regulation of Metabolism
What happens to glucagon and insulin levels during the well-fed state?
Glucagon decreases and insulin increases.
What is the significance of allosteric regulation in glycogen metabolism?
It regulates glycogen synthesis and degradation.
p.16
Hormonal Regulation of Metabolism
What does cAMP activate?
cAMP-dependent protein kinase A (PKA).
p.30
Hormonal Regulation of Metabolism
What is the result of PK phosphorylation?
Decreased glycolysis and increased gluconeogenesis.
p.77
Hormonal Regulation of Metabolism
How is hormone-sensitive lipase (HSL) activated?
By phosphorylation from PKA.
p.83
Hormonal Regulation of Metabolism
How does AMPK regulate ACC?
AMPK phosphorylates ACC, inhibiting fatty acid synthesis and promoting fatty acid oxidation.
p.75
Fatty Acid Synthesis and Breakdown
What is the effect of epinephrine and glucagon on ACC?
They lead to phosphorylation and inactivation of ACC.
p.73
Fatty Acid Synthesis and Breakdown
What are the end products of fatty acid degradation?
The end products are acetyl-CoA, NADH, and FADH2.
p.95
Fructose and Ethanol Metabolism
What byproduct is generated during alcohol metabolism?
Reactive oxygen species (ROS), including H2O2.
Why does Hexokinase have a low V_max for glucose?
To avoid trapping too many cellular phosphates in the form of phosphorylated hexoses.
What is the primary product of glycogen degradation?
Glucose 1-phosphate (G1P).
Why is the production of acetyl-CoA in fatty acid oxidation essential for gluconeogenesis?
Acetyl-CoA itself cannot be converted into glucose, but its production indicates that fatty acids are being oxidized, which provides energy and helps maintain the balance of metabolic intermediates necessary for gluconeogenesis.
p.53
Tricarboxylic Acid (TCA) Cycle
Which enzyme in the TCA cycle is stimulated by ADP?
Isocitrate dehydrogenase.
p.27
Hormonal Regulation of Metabolism
What inhibits Hexokinase?
Glucose-6-phosphate (G6P).
p.76
Fatty Acid Synthesis and Breakdown
When does the liver synthesize fatty acids de novo?
When dietary carbohydrate is high.
p.89
Metabolic Disorders Related to Carbohydrate Consumption
What condition can result from chronic fructose consumption?
Non-alcoholic fatty liver disease (NAFLD).
What is produced from one molecule of glucose during glycolysis?
2 pyruvate, 2 NADH, 2 ATP, and 2 H2O.
p.52
Tricarboxylic Acid (TCA) Cycle
What is the final pathway for fuel molecules in the TCA cycle?
Complete oxidation to CO2.
p.66
Hormonal Regulation of Metabolism
What happens to glycogen phosphorylase kinase when insulin binds?
It becomes inactivated (dephosphorylated), stopping glycogenolysis.
What is the primary cycle involved in gluconeogenesis that includes alanine?
The Glucose-Alanine Cycle.
p.75
Fatty Acid Synthesis and Breakdown
What is the role of Acetyl-CoA carboxylase (ACC) in fatty acid synthesis?
ACC catalyzes the conversion of Acetyl-CoA to malonyl-CoA, a key step in fatty acid synthesis.
p.84
Fructose and Ethanol Metabolism
What is a potential consequence of excessive fructose consumption?
It can lead to metabolic disorders such as insulin resistance and fatty liver disease.
What inhibits glycogen phosphorylase in glycogenolysis?
G6P and ATP in liver and muscle.
p.67
Hormonal Regulation of Metabolism
How does glucagon affect glycogen synthesis?
Glucagon inhibits glycogen synthesis.
p.51
Hormonal Regulation of Metabolism
What activates PDH phosphatase?
Calcium ions (Ca2+), especially important in skeletal muscle.
p.72
Metabolic Disorders Related to Carbohydrate Consumption
What is the primary defect in Type 1a glycogen storage disease?
Deficiency of glucose 6-phosphatase.
p.14
Hormonal Regulation of Metabolism
What are the biological effects of insulin?
Promotes glucose uptake in adipose, muscle, and liver cells.
p.13
Hormonal Regulation of Metabolism
What does insulin favor the synthesis of?
Glycogen, protein, and triacylglycerols.
p.77
Fatty Acid Synthesis and Breakdown
What enzyme acts on diacylglycerol (DAG) during lipolysis?
Hormone-sensitive lipase (HSL).
What does K_m represent in enzyme kinetics?
The substrate concentration at which the reaction velocity equals half of V_max.
What is the significance of gluconeogenesis?
It helps maintain blood glucose levels during fasting or intense exercise.
p.33
Hormonal Regulation of Metabolism
What role does fructose-2,6-bisphosphate play in regulating PFK-1?
Fructose-2,6-bisphosphate acts as an allosteric activator of PFK-1, enhancing its activity.
What activates PFK - 1 allosterically?
AMP, indicating depleted energy stores.
p.81
Hormonal Regulation of Metabolism
What would be the overall effect of inhibiting PDE in adipocytes?
Inhibition of PDE would lead to increased cAMP levels, enhancing the lipolytic response to epinephrine.
p.16
Hormonal Regulation of Metabolism
What is the effect of PKA activation?
Increases the phosphorylation of specific enzymes or other proteins involved in carbohydrate and lipid metabolism.
How many glycolytic reactions are reversible and used in gluconeogenesis?
Seven glycolytic reactions are reversible.
p.87
Fructose and Ethanol Metabolism
Which aldolase enzymes are involved in cleaving F1,6-bisP?
Aldolase A, aldolase B, and aldolase C.
p.7
Hormonal Regulation of Metabolism
What is the primary function of intermediary metabolism?
To store and generate metabolic energy.
Where does lactate used in gluconeogenesis primarily come from?
Muscle and red blood cells.
p.86
Fructose and Ethanol Metabolism
What are some common sources of sucrose in the diet?
Honey, fruit, syrup, and table sugar.
What is the primary requirement for gluconeogenesis?
Both mitochondrial and cytosolic enzymes.
How can gluconeogenic amino acids be utilized in metabolism?
They can be catabolized to intermediates of the TCA cycle.
p.54
Tricarboxylic Acid (TCA) Cycle
What is the PDH complex?
The Pyruvate Dehydrogenase complex, which converts pyruvate into acetyl-CoA, linking glycolysis to the TCA cycle.
p.79
Fatty Acid Synthesis and Breakdown
What are the four reactions involved in β-oxidation?
1. An oxidation that produces FADH2, 2. A hydration step, 3. A second oxidation that produces NADH, 4. A thiolytic cleavage that releases acetyl-CoA.
What is the role of allosteric control in glycogen metabolism?
It allows a rapid response to the needs of a cell and can override hormone-mediated covalent regulation.
What are the metabolic fates of glucose?
Glucose can be used for energy production, stored as glycogen, or converted to fatty acids.
p.14
Hormonal Regulation of Metabolism
How does insulin promote glucose uptake in muscle and adipose tissues?
Via GLUT4 (insulin dependent).
Why is gluconeogenesis important?
Because glucose may not always be available from external sources or intracellular stores.
p.98
Hormonal Regulation of Metabolism
What regulates glucose catabolism?
Regulated by hormones, allosteric effects, and covalent modifications.
p.10
Hormonal Regulation of Metabolism
What is the role of hormones in glucose homeostasis?
To maintain glucose levels within the normal range.
p.15
Hormonal Regulation of Metabolism
How does glucagon maintain blood glucose levels?
By activating hepatic glycogenolysis and gluconeogenesis.
p.34
Hormonal Regulation of Metabolism
How does insulin affect gluconeogenesis?
Insulin inhibits gluconeogenesis.
What is the function of Glucokinase in glycolysis?
It converts glucose (G) to glucose-6-phosphate (G6P).
p.83
Fatty Acid Synthesis and Breakdown
What would be the consequence of replacing the Ser residue in ACC with Ala?
It would prevent phosphorylation by AMPK, likely leading to increased fatty acid synthesis and decreased fatty acid oxidation.
p.97
Metabolic Disorders Related to Carbohydrate Consumption
What is the disease spectrum caused by overconsumption of alcohol?
Alcoholic fatty liver disease and related conditions.
What reaction does Phosphofructokinase-1 (PFK-1) catalyze?
It catalyzes the conversion of fructose-6-phosphate (F6P) to fructose-1,6-bisphosphate (F1,6-bisP).
p.94
Fructose and Ethanol Metabolism
Which enzyme converts acetaldehyde to acetic acid?
Acetaldehyde dehydrogenase (ALDH).
p.18
Hormonal Regulation of Metabolism
How does insulin affect glycogen synthesis?
Insulin stimulates glycogen synthesis in the liver and muscle.
What causes elevated levels of acetyl-CoA in mitochondria?
Increased lipolysis in adipose tissues.
When does glycogenesis accelerate in the liver?
During periods when the body has been well fed.
p.55
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What type of reactions are involved in the Electron Transport Chain?
Oxidation-reduction (Redox) reactions.
p.82
Fatty Acid Synthesis and Breakdown
Why does newly synthesized acyl-CoA not get oxidized?
Newly synthesized acyl-CoA is typically directed towards fatty acid synthesis rather than oxidation, as it is in a state of high energy and is not yet needed for energy production.
p.92
Metabolic Disorders Related to Carbohydrate Consumption
What are the potential consequences of high sugar intake from soft drinks?
Increased risk of dental problems, weight gain, and chronic diseases.
p.71
Hormonal Regulation of Metabolism
What role does glucagon play in glucose production by the liver?
Glucagon stimulates the liver to convert stored glycogen into glucose and to produce glucose from non-carbohydrate sources.
p.89
Fructose and Ethanol Metabolism
What process does fructose promote in the liver?
Glycolysis (uptake of glucose).
How many glucose units does glycogenin transfer to form a primer?
The first few glucose units (1st to 8th).
p.14
Hormonal Regulation of Metabolism
What is the role of receptor tyrosine kinase in insulin signaling?
It phosphorylates and activates other protein kinases and phosphatases.
p.32
Hormonal Regulation of Metabolism
Which isozyme will more closely approach V max at a blood glucose concentration of 5 mM?
Hexokinase, because its K m is much lower than the blood glucose concentration.
Where is Glucokinase (GK) primarily found?
In the liver and β cells of the pancreas.
Which four major tissues play a dominant role in glucose homeostasis?
Liver, adipose, muscle, and brain.
Which pathway generates pentose phosphate and NADPH from glucose?
Pentose phosphate pathway (PPP).
p.13
Hormonal Regulation of Metabolism
What decreases the synthesis and release of insulin?
Scarcity of dietary fuels and periods of physiologic stress mediated by epinephrine.
p.66
Hormonal Regulation of Metabolism
How does insulin affect glycogen phosphorylase?
It inactivates glycogen phosphorylase (dephosphorylated) to stop glycogenolysis.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What role do electron carriers play in the ETC?
They transport electrons from NADH and FADH2 to the final electron acceptor, usually oxygen.
Do animals use exogenous glucose?
Yes, as an important energy source.
p.97
Fatty Acid Synthesis and Breakdown
What is the effect of increased malonyl-CoA on triglyceride content?
It increases triglyceride (TAG) content.
p.20
Hormonal Regulation of Metabolism
What are the symptoms associated with glucagonoma?
Weight loss, hyperglycemia, and skin rash.
p.87
Fructose and Ethanol Metabolism
Why is fructose metabolism faster than glucose metabolism?
Because the trioses formed from F1P bypass PFK-1 regulation.
p.74
Fatty Acid Synthesis and Breakdown
What is the role of acetyl-CoA carboxylase (ACC) in fatty acid synthesis?
It catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, which is the regulated step.
p.75
Fatty Acid Synthesis and Breakdown
What activates AMPK?
AMP activates AMPK allosterically, while phosphorylation via several kinases covalently activates it.
p.2
Fatty Acid Synthesis and Breakdown
What processes are involved in fatty acid metabolism?
Synthesis and breakdown of fatty acids.
p.2
Hormonal Regulation of Metabolism
What regulates fatty acid synthesis and breakdown?
Hormonal and nutritional factors.
p.2
Fructose and Ethanol Metabolism
What is involved in fructose metabolism?
The conversion of fructose into intermediates for energy production.
What are the two phases of glycolysis?
Energy investment phase and energy payoff phase.
p.51
Hormonal Regulation of Metabolism
What activates PDH kinase?
High energy signals such as ATP, acetyl-CoA, and NADH.
p.27
Hormonal Regulation of Metabolism
How is Glucokinase (GK) indirectly inhibited?
By fructose-6-phosphate (F6P).
What happens at the nonreducing ends of the glycogen chain?
α(1 → 4) glycosidic bonds are broken to release glucose 1-phosphate.
p.72
Metabolic Disorders Related to Carbohydrate Consumption
Why is hypoglycemia severe in Type 1a glycogen storage disease?
It is due to glucose 6-phosphatase deficiency, which prevents the conversion of glycogen to glucose, leading to significant drops in blood sugar levels.
p.76
Fatty Acid Synthesis and Breakdown
What happens to the fatty acids synthesized de novo in the liver?
They are converted into triacylglycerol (TAG) and transported to extrahepatic tissues for storage.
Where does gluconeogenesis primarily occur in the body?
In the liver and to a lesser extent in the kidneys.
In which type of cells is glycolysis the sole provider of ATP?
In cells that lack mitochondria, such as erythrocytes.
p.27
Hormonal Regulation of Metabolism
What happens to GK in the presence of F6P?
It is translocated into the nucleus and binds to the glucokinase regulatory protein (GKRP), rendering it inactive.
p.41
Hormonal Regulation of Metabolism
How does the insulin to glucagon ratio affect F2,6-bisP concentration?
Glucagon ↑ leads to F2,6-bisP ↓; Insulin ↑ leads to F2,6-bisP ↑.
p.79
Fatty Acid Synthesis and Breakdown
What happens to the reduced coenzymes NADH and FADH2 during β-oxidation?
They are oxidized by the electron transport chain (ETC).
What is the brain's role in glucose homeostasis?
It is the consumer with a constant need for glucose.
Why is max enzyme activity not reached after a meal?
To prevent hyperglycemia during the absorptive period.
p.98
Fatty Acid Synthesis and Breakdown
How are glucose and fatty acids interconverted?
Through processes like gluconeogenesis and fatty acid synthesis.
What function does adipose tissue serve in glucose homeostasis?
Acts as the energy storage depot.
p.57
Hormonal Regulation of Metabolism
What is the primary location of brown adipose tissue?
It is primarily located in specific areas of the body, such as around the neck and along the spine.
p.95
Fructose and Ethanol Metabolism
What enzyme oxidizes ethanol to acetaldehyde in the liver?
Alcohol dehydrogenase (ADH).
p.15
Hormonal Regulation of Metabolism
What conditions lead to decreased glucagon secretion?
Elevated blood glucose and insulin levels.
p.2
Hormonal Regulation of Metabolism
What regulates glycogen synthesis and breakdown?
Hormonal signals such as insulin and glucagon.
p.95
Fructose and Ethanol Metabolism
What is acetaldehyde metabolized to in the liver?
Acetate, by aldehyde dehydrogenase - 2 (ALDH2).
What is the role of Pyruvate kinase in glycolysis?
It converts phosphoenolpyruvate (PEP) to pyruvate.
p.5
Carbohydrate Digestion and Absorption
What products are generated from the hydrolysis of starches and glycogen by α-amylase?
Limit dextrin and maltose.
What type of polymer is glycogen?
A branched-chain polymer of glucose.
p.14
Hormonal Regulation of Metabolism
What type of receptors does insulin bind to?
Insulin receptors (receptor tyrosine kinase).
p.82
Fatty Acid Synthesis and Breakdown
What is the primary fate of newly synthesized acyl-CoA?
It is primarily used for fatty acid synthesis.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is the primary function of the Electron Transport Chain?
To transfer electrons and pump protons across the mitochondrial membrane.
p.67
Hormonal Regulation of Metabolism
What stimulates glycogen degradation?
Glucagon and epinephrine stimulate glycogen degradation.
p.52
Tricarboxylic Acid (TCA) Cycle
What is another name for the Tricarboxylic Acid (TCA) Cycle?
Citric acid cycle or Kreb’s cycle.
p.65
Hormonal Regulation of Metabolism
What hormones are involved in the regulation of glycogen metabolism during fasting?
Glucagon and epinephrine.
p.96
Metabolic Disorders Related to Carbohydrate Consumption
What is a potential progression of liver disease due to acetaldehyde?
Progression from liver fibrosis to cirrhosis.
p.56
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is the chemiosmotic model?
A model that explains how ATP is generated in mitochondria through the movement of protons across a membrane.
What type of reaction converts pyruvate to acetyl-CoA?
Irreversible oxidative decarboxylation.
p.20
Hormonal Regulation of Metabolism
How does the presentation of a glucagonoma differ from an insulinoma?
Glucagonoma leads to hyperglycemia and symptoms of diabetes, while insulinoma causes hypoglycemia.
p.77
Fatty Acid Synthesis and Breakdown
Which enzyme initiates lipolysis in adipocytes?
Adipose triglyceride lipase (ATGL).
What is the primary role of the liver in glucose homeostasis?
Acts as the provider of glucose.
p.73
Fatty Acid Synthesis and Breakdown
What is the primary process for synthesizing fatty acids?
Fatty acid synthesis occurs through the process of lipogenesis.
What happens to G6P in muscle tissue?
It enters glycolysis to produce energy.
p.78
Fatty Acid Synthesis and Breakdown
What is the role of the carnitine shuttle?
To transport long-chain fatty acids into the mitochondrial matrix.
What are the three regulatory steps in glycolysis?
1. Glucokinase (GK) / Hexokinase I, II, III: G → G6P; 2. Phosphofructokinase-1 (PFK-1): F6P → F1,6-bisP; 3. Pyruvate kinase: PEP → Pyruvate.
p.10
Metabolic Disorders Related to Carbohydrate Consumption
What happens when blood glucose levels exceed 10 mmol/L?
Glucosuria (glucose in urine) occurs.
p.79
Fatty Acid Synthesis and Breakdown
How does acetyl-CoA affect pyruvate carboxylase?
Acetyl-CoA is a positive allosteric effector of pyruvate carboxylase.
p.12
Hormonal Regulation of Metabolism
What must be coordinated in metabolic pathways?
The production of energy or the synthesis of end products to meet the needs of the cell.
p.72
Metabolic Disorders Related to Carbohydrate Consumption
What is the primary defect in Type VI glycogen storage disease?
Deficiency of liver glycogen phosphorylase.
What happens to pyruvate at low levels of acetyl-CoA?
Pyruvate is primarily oxidized to produce acetyl-CoA.
What is the Michaelis-Menten equation used for?
To describe the saturation of enzymes with respect to substrate concentration [S].
What is gluconeogenesis?
The synthesis of glucose from non-carbohydrate sources.
What is the role of acetyl-CoA in relation to pyruvate during gluconeogenesis?
It diverts pyruvate away from oxidation and toward gluconeogenesis.
What happens to glycogen synthase when PKA is activated?
It becomes inactivated (phosphorylated) to stop glycogenesis.
p.77
Hormonal Regulation of Metabolism
How does insulin affect the expression of adipose triglyceride lipase (ATGL)?
Insulin suppresses the expression of ATGL.
p.12
Hormonal Regulation of Metabolism
What type of regulation is activated by second messengers of glucagon and insulin?
Covalent regulation by protein kinase/phosphatase.
p.82
Fatty Acid Synthesis and Breakdown
What role does acyl-CoA play in metabolism?
Acyl-CoA serves as a key intermediate in both fatty acid synthesis and oxidation.
p.95
Fructose and Ethanol Metabolism
What does drinking refer to in this context?
The consumption of beverages containing alcohol, such as beer and wine.
What does the hydrolysis of triacylglycerol stored in adipose tissue produce?
Free fatty acids and glycerol.
What type of linkage is formed by glycogenin during glycogenesis?
Short α (1 → 4) linked primer.
What happens to oxaloacetate (OAA) after its formation in gluconeogenesis?
It is reduced to malate for transfer to the cytosol.
What does a high Km value indicate about Glucokinase?
It implies low affinity for glucose.
p.16
Hormonal Regulation of Metabolism
Where are glucagon receptors primarily located?
On the cell membrane of hepatocytes (not found on skeletal muscle).
p.20
Hormonal Regulation of Metabolism
What type of cells does a glucagonoma derive from?
Alpha cells of the pancreas.
What happens to lactate in the liver?
It is reconverted to glucose and released back into circulation.
What is the role of Phosphofructokinase - 1 (PFK - 1) in glycolysis?
It is the rate-limiting and committed step in glycolysis.
p.15
Hormonal Regulation of Metabolism
What triggers an increase in glucagon secretion?
Low blood glucose, amino acids, and epinephrine.
What is the role of ATP in gluconeogenesis?
ATP is required for the conversion processes in gluconeogenesis.
p.79
Fatty Acid Synthesis and Breakdown
What is the significance of the link between fatty acid oxidation and gluconeogenesis?
Acetyl-CoA produced from β-oxidation activates pyruvate carboxylase, linking the two metabolic pathways.
What is glycolysis?
A metabolic pathway that converts glucose into pyruvate, producing ATP and NADH.
What does a low K_m value indicate about an enzyme's affinity for glucose?
It implies that the enzyme has a high affinity for glucose.
p.83
Fatty Acid Synthesis and Breakdown
What effect would replacing the Ser residue in ACC with Asp have?
It could mimic phosphorylation, potentially leading to decreased fatty acid synthesis and increased fatty acid oxidation.
What is the effect of glucose concentration on hexokinase and glucokinase?
It affects the rate of phosphorylation catalyzed by both enzymes.
What is the relationship between V_0 and V_max in the Michaelis-Menten Equation?
V_0 = V_max [S] / ([S] + K_m).
What is glycogenesis?
The process of converting glucose into glycogen for storage.
p.29
Hormonal Regulation of Metabolism
What occurs to glucagon and insulin levels during fasting?
Glucagon increases and insulin decreases.
p.10
Fatty Acid Synthesis and Breakdown
What is lipogenesis?
The process of converting excess glucose into fat.
p.28
Hormonal Regulation of Metabolism
What does the regulation of PFK - 1 and fructose 1,6-bisphosphatase ensure?
That glycolysis and gluconeogenesis are not fully active at the same time.
What is the role of fructose 1,6-bisphosphatase in gluconeogenesis?
It is one of the irreversible bypass reactions.
How does carbohydrate intake affect intramuscular TAG content?
It increases intramuscular TAG content, which serves as an energy supply during endurance events like marathons.
What role does PFK-2 play in the regulation of fructose 2,6-bisphosphate?
PFK-2 is responsible for synthesizing fructose 2,6-bisphosphate.
p.18
Hormonal Regulation of Metabolism
What triggers the release of glucagon?
Decreased blood glucose levels, especially during fasting.
p.66
Hormonal Regulation of Metabolism
What effect does insulin binding have on protein phosphatase-1 (PP1)?
It activates the signal cascade of PP1, favoring dephosphorylation.
p.53
Tricarboxylic Acid (TCA) Cycle
Which enzyme is inhibited by succinyl CoA, NADH, and ATP?
α-ketoglutarate dehydrogenase.
p.67
Hormonal Regulation of Metabolism
What inhibits glycogen degradation?
Insulin inhibits glycogen degradation.
p.84
Fructose and Ethanol Metabolism
What can glyceraldehyde be converted into during fructose metabolism?
Glyceraldehyde can be converted into glycerol or enter glycolysis.
What activates glycogen synthase in glycogenesis?
G6P (glucose-6-phosphate) in liver and muscle.
p.80
Hormonal Regulation of Metabolism
How are fatty acid synthesis and degradation regulated?
Through coordinated hormonal and enzymatic regulation.
p.89
Metabolic Disorders Related to Carbohydrate Consumption
How does the liver respond to increased fructose consumption?
By increasing the export of lipoproteins, leading to obesity.
p.81
Hormonal Regulation of Metabolism
What is the role of cAMP in adipocytes when responding to epinephrine?
cAMP acts as a second messenger that activates protein kinase A (PKA), which promotes lipolysis.
p.13
Hormonal Regulation of Metabolism
What are the metabolic effects of insulin?
Anabolic, favoring the induction of hepatic GK expression and altering intracellular glucose concentrations.
p.98
Metabolic Disorders Related to Carbohydrate Consumption
Can dietary carbohydrates improve exercise performance?
Yes, they can provide necessary energy for physical activity.
What are the two pathways for converting pyruvate to oxaloacetate?
1. Lactate → Pyruvate → OAA → PEP; 2. Amino Acids → Pyruvate → OAA → Malate → OAA → PEP.
p.33
Hormonal Regulation of Metabolism
How does the carbohydrate-rich meal affect the activity of PK?
The activity of PK is also high, promoting glycolysis and energy production.
What is glycogen?
A stored form of glucose in the body, primarily found in the liver and muscles.
p.75
Fatty Acid Synthesis and Breakdown
What leads to allosteric inactivation of ACC?
Long-chain fatty acyl-CoA causes depolymerization of ACC.
p.98
Metabolic Disorders Related to Carbohydrate Consumption
What metabolic disorders are caused by high sugar consumption?
Conditions like obesity, type 2 diabetes, and metabolic syndrome.
How does Glucokinase respond to changes in blood glucose concentration?
It regulates glucose production based on glucose levels.
What is the significance of the Cori Cycle in metabolism?
It prevents the accumulation of lactate in tissues and blood.
Can muscle tissue contribute directly to blood glucose maintenance?
No, it cannot contribute directly.
What effect does exercise/training have on glycogen accumulation?
It can increase glycogen accumulation in muscle.
How do the major tissues coordinate to achieve glucose homeostasis?
They metabolically coordinate to achieve homeostasis.
p.18
Hormonal Regulation of Metabolism
What effect does glucagon have on glycogen stores?
Glucagon promotes the breakdown of glycogen into glucose.
What is the significance of fructose-2,6-bisphosphate (F2,6-bisP) in glycolysis?
It acts as a regulator of Phosphofructokinase-1 (PFK-1).
p.73
Fatty Acid Synthesis and Breakdown
What is the significance of fatty acid synthesis and degradation?
They are crucial for energy storage and utilization in the body.
p.5
Carbohydrate Digestion and Absorption
Why is cellulose not digested in humans?
Because cellulase does not exist in humans.
p.95
Fructose and Ethanol Metabolism
What system does ethanol enter after absorption?
The hepatic portal system to the liver.
p.74
Fatty Acid Synthesis and Breakdown
Which enzyme catalyzes the remaining reactions of fatty acid synthesis in eukaryotes?
Fatty acid synthase (FAS).
What happens to alanine in the liver during gluconeogenesis?
Hepatic transamination converts alanine back to pyruvate.
p.5
Carbohydrate Digestion and Absorption
What is the primary location for carbohydrate digestion in the gastrointestinal tract?
Mouth and small intestine.
p.73
Fatty Acid Synthesis and Breakdown
What is the role of malonyl-CoA in fatty acid synthesis?
Malonyl-CoA provides the two-carbon units for elongating the fatty acid chain.
p.80
Fatty Acid Synthesis and Breakdown
What is a key enzyme involved in fatty acid degradation?
Carnitine acyltransferase.
p.55
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is the primary source of ATP generated from glucose breakdown?
The Electron Transport Chain (ETC).
Is gluconeogenesis a simple reversal of glycolysis?
No, gluconeogenesis is not a simple reversal of glycolysis.
p.73
Fatty Acid Synthesis and Breakdown
What is the primary pathway for the degradation of fatty acids?
Fatty acids are primarily degraded through beta-oxidation.
What accelerates glycogenolysis in the liver?
During periods of fasting.
How many ATP molecules are produced in glycolysis?
A net gain of 2 ATP molecules per glucose molecule.
What are the primary sources of glucose in the body?
Dietary carbohydrates, liver glycogen, and amino acids.
What is the primary function of glycogen in the body?
To serve as a readily available source of glucose for energy.
p.55
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is the term for the coupling of oxygen consumption, H+ gradient formation, and ATP synthesis?
Oxidative phosphorylation.
What is the significance of the bypass reactions in gluconeogenesis?
They allow gluconeogenesis to proceed despite the irreversible steps of glycolysis.
What is the role of Pyruvate dehydrogenase (E1) in the PDH complex?
Decarboxylation of pyruvate.
p.20
Hormonal Regulation of Metabolism
What are the symptoms associated with insulinoma?
Hypoglycemia, confusion, sweating, and palpitations.
p.83
Fatty Acid Synthesis and Breakdown
What is the role of acetyl-CoA carboxylase (ACC) in fat metabolism?
ACC is involved in the conversion of acetyl-CoA to malonyl-CoA, a key step in fatty acid synthesis.
p.94
Fructose and Ethanol Metabolism
What enzyme is primarily involved in the conversion of ethanol to acetaldehyde?
Alcohol dehydrogenase (ADH).
What is glycogen metabolism?
The synthesis and breakdown of glycogen.
p.13
Hormonal Regulation of Metabolism
What does insulin inhibit?
The mobilization of glycogen, protein, and triacylglycerols.
p.87
Fructose and Ethanol Metabolism
What is the role of hexokinase in fructose metabolism?
It has a low affinity for fructose, resulting in little phosphorylation to form F6P.
What is the overall reaction catalyzed by the pyruvate dehydrogenase complex?
Conversion of pyruvate to acetyl-CoA and production of NADH.
What is the role of Hexokinase in glucose metabolism?
It maintains low intracellular glucose levels to facilitate glucose uptake.
p.87
Fructose and Ethanol Metabolism
What is the significance of ATP in fructose metabolism?
ATP is used as a phosphate donor by fructokinase to convert fructose to F1P.
p.18
Hormonal Regulation of Metabolism
How does insulin influence fat metabolism?
Insulin promotes fat storage and inhibits fat breakdown.
p.49
Tricarboxylic Acid (TCA) Cycle
What is the primary function of the Tricarboxylic Acid (TCA) Cycle?
To oxidize acetyl-CoA to produce energy carriers like NADH and FADH2.
What is the significance of the Km value in enzyme kinetics?
It represents the substrate concentration at which the reaction velocity is half of Vmax.
How does branching affect the solubility and compactness of glycogen?
It increases both solubility and compactness.
What is glycogenin?
A protein that serves as a primer for glycogen synthesis.
What activates glycogen phosphorylase in muscle?
AMP and Ca2+ binding on calmodulin (CaM).
p.65
Hormonal Regulation of Metabolism
How is glycogen phosphorylase kinase activated?
By PKA through phosphorylation.
p.16
Hormonal Regulation of Metabolism
What does the activation of adenylyl cyclase cause?
A rise in cyclic AMP (cAMP).
p.30
Hormonal Regulation of Metabolism
What effect does increased cAMP have on Pyruvate Kinase?
It leads to phosphorylation by cAMP-dependent protein kinase A, making PK inactive.
What is glycogenolysis?
The process of breaking down glycogen to release glucose.
p.75
Fatty Acid Synthesis and Breakdown
How does AMP-activated protein kinase (AMPK) affect ACC?
AMPK phosphorylates and inactivates ACC.
p.66
Hormonal Regulation of Metabolism
What role does phosphodiesterase play in glycogen metabolism when insulin is present?
It degrades cAMP to inhibit glycogenolysis.
How much carbohydrate is typically consumed during glycogen loading?
500g/day, which is about 70% of total calorie intake.
p.33
Hormonal Regulation of Metabolism
Why is the phosphorylation state of hepatic enzymes important after a carbohydrate meal?
It ensures efficient glucose metabolism and energy production in response to increased glucose availability.
p.15
Hormonal Regulation of Metabolism
When is glucagon secretion significantly decreased?
Following ingestion of glucose or carbohydrate-rich meals.
What types of meals are recommended for replenishing glycogen content?
High carbohydrate meals, such as large quantities of pasta, rice, or bread.
p.94
Metabolic Disorders Related to Carbohydrate Consumption
How does chronic alcohol consumption affect the liver?
It can lead to fatty liver, hepatitis, and cirrhosis.
What is one benefit of high carbohydrate meals in relation to glycogen?
They replenish glycogen content, providing greater energy reserves.
What happens to most of the glucose formed during gluconeogenesis?
It is released into the blood.
When does glycogenesis begin in skeletal muscle?
As soon as the muscle is again at rest.
What is the function of glucose 6-phosphatase in gluconeogenesis?
It is one of the irreversible bypass reactions.
What triggers the conversion of glycogen to glucose during fasting?
Low blood glucose levels.
p.49
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is oxidative phosphorylation?
The process of ATP production that occurs as protons flow back into the mitochondrial matrix through ATP synthase.
p.76
Fatty Acid Synthesis and Breakdown
What are the potential consequences of excess de novo lipogenesis?
Fatty liver and hypertriglyceridemia.
p.81
Hormonal Regulation of Metabolism
What is the function of phosphodiesterase (PDE) in the context of cAMP?
PDE breaks down cAMP, thus regulating its levels and the duration of its signaling effects.
What is the effect of dephosphorylation of fructose 1,6-bisphosphate?
It is part of the regulation of gluconeogenesis.
What is the effect of increased F2,6-BisP during the well-fed state?
It indicates an increase in glucose and promotes glycolysis in the liver.
p.98
Fructose and Ethanol Metabolism
How does ethanol consumption affect metabolism?
It can disrupt glucose metabolism and lead to fatty liver disease.
p.73
Fatty Acid Synthesis and Breakdown
Where does beta-oxidation primarily occur?
Beta-oxidation primarily occurs in the mitochondria.
What are some noncarbohydrate precursors for glucose formation?
Lactate, pyruvate, glycerol, and α-keto acids.
What are the three bypass reactions in gluconeogenesis?
1. Pyruvate carboxylase and PEP carboxykinase, 2. Fructose 1,6-bisphosphatase, 3. Glucose 6-phosphatase.
What is the function of fructose 2,6-bisphosphate (F2,6-bisP) in relation to gluconeogenesis?
It inhibits fructose 1,6-bisphosphatase.
What is the significance of glucose for cells?
It serves as a primary energy source.
What role does NAD+ play in glycolysis?
It acts as an electron carrier, being reduced to NADH.
What is the significance of glycolysis in cellular respiration?
It is the first step in the breakdown of glucose for energy.
What is unique about the enzymes in each of the major tissues involved in glucose metabolism?
Each tissue contains unique sets of enzymes specialized for specific fuels.
p.29
Hormonal Regulation of Metabolism
What is the effect of fasting on adenylyl cyclase?
Adenylyl cyclase is activated.
p.94
Fructose and Ethanol Metabolism
What is the role of the microsomal ethanol-oxidizing system (MEOS)?
To metabolize alcohol at higher concentrations.
p.2
Fructose and Ethanol Metabolism
What is ethanol metabolism?
The process of breaking down ethanol for energy.
Where is glycogen primarily stored?
In the liver and muscle tissues.
How are glycogen synthase and glycogen phosphorylase regulated?
By hormones (phosphorylation and dephosphorylation) and allosteric control (by effector molecules).
What effect does branching have on glycogen synthesis and degradation?
It increases the rate of both processes due to more non-reducing ends.
p.75
Fatty Acid Synthesis and Breakdown
What is the effect of insulin on ACC?
Insulin leads to dephosphorylation and activation of ACC.
p.73
Fatty Acid Synthesis and Breakdown
How are fatty acids activated before degradation?
Fatty acids are activated by conversion to acyl-CoA.
How many glucose units can be in one glycogen molecule?
Up to 100,000 glucose units.
What does a V0/Vmax ratio of 100% indicate for Hexokinase?
It indicates that Hexokinase is fully saturated with substrate at normal blood glucose levels.
What are the two key enzymes involved in glycogen metabolism?
Glycogen synthase (for glycogenesis) and glycogen phosphorylase (for glycogenolysis).
p.18
Hormonal Regulation of Metabolism
What triggers the release of insulin?
Increased blood glucose levels after eating.
What is the role of allosteric control in glycogen metabolism?
To meet the needs of a particular tissue.
p.49
Tricarboxylic Acid (TCA) Cycle
What is the Link Reaction?
The process that converts pyruvate into acetyl-CoA, linking glycolysis to the TCA cycle.
p.18
Hormonal Regulation of Metabolism
What is the effect of glucagon on fatty acid metabolism?
Glucagon stimulates the breakdown of fatty acids for energy.
What is the effect of fasting on glycolysis and gluconeogenesis in the liver?
Glycolysis decreases and gluconeogenesis increases.
What is the relationship between glycolysis and gluconeogenesis?
They are opposing pathways.
What happens to pyruvate after glycolysis under anaerobic conditions?
It is converted to lactate or ethanol, depending on the organism.
p.94
Metabolic Disorders Related to Carbohydrate Consumption
What effect does alcohol have on blood sugar levels?
It can cause hypoglycemia.
p.18
Hormonal Regulation of Metabolism
How do insulin and glucagon work together in metabolism?
They maintain blood glucose homeostasis by opposing actions.
p.49
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What is the main purpose of the Electron Transport Chain?
To transfer electrons from NADH and FADH2 to oxygen, creating a proton gradient.
p.49
Tricarboxylic Acid (TCA) Cycle
What are the end products of the TCA cycle?
NADH, FADH2, ATP, and carbon dioxide.
What is the conversion process involving fructose 6-phosphate?
It is converted to triose phosphates.
p.49
Electron Transport Chain (ETC) and Oxidative Phosphorylation
Where does the Electron Transport Chain (ETC) occur?
In the inner mitochondrial membrane.
p.55
Electron Transport Chain (ETC) and Oxidative Phosphorylation
What can happen to the H+ gradient and ATP synthesis?
They can be uncoupled, leading to heat generation.
Where can large glycogen particles be found?
In a section of a liver cell.
p.5
Carbohydrate Digestion and Absorption
What type of glycosidic linkages does cellulase break down?
β 1-4 glycosidic linkages in cellulose.
What is the function of FBP-2?
FBP-2 (Fructose 2,6-bisphosphatase) is responsible for degrading fructose 2,6-bisphosphate.
p.49
Tricarboxylic Acid (TCA) Cycle
How does the Link Reaction contribute to cellular respiration?
It produces acetyl-CoA, which enters the TCA cycle for further energy extraction.
What is the role of hormonal regulation in glycogen metabolism?
To meet the needs of the body as a whole.
