Module 5-6 Review ChatGPT Flashcards
What are the primary fuel sources in myocytes, neurons, and erythrocytes during a keto diet
Fatty acids in myocytes, ketone bodies in neurons, and glucose in erythrocytes
What is the primary fuel used by the brain during prolonged fasting
Ketone bodies
What are the 4 main promoting and 2 inhibitory effects of insulin in the fed state
Glucose uptake, glycogen synthesis, lipogenesis, and protein synthesis
Gluconeogenesis and glycogenolysis
What triggers glycogenolysis and gluconeogenesis during fasting
The release of glucagon and epinephrine
What is the role of glucagon during prolonged fasting
Lipolysis
Ketogenesis
Gluconeogenesis
What are the main differences between saturated and unsaturated fats
Saturated fats have no double bonds and are typically solid at room temperature, while unsaturated fats have one or more double bonds and are typically liquid
What promoting (3) and inhibitory (1) effects does cortisol have on metabolism
Gluconeogenesis, proteolysis, and lipolysis
Glucose uptake in peripheral tissues
What promoting (2) and inhibitory (1) roles does epinephrine play in fuel mobilization
Rapidly mobilizes energy by increasing glycogenolysis and lipolysis
Insulin secretion
What is the significance of malonyl-CoA in fatty acid metabolism
Malonyl-CoA inhibits carnitine palmitoyltransferase I (CPT I), preventing fatty acid oxidation
What is the function of the pyruvate dehydrogenase complex
The pyruvate dehydrogenase complex converts pyruvate to acetyl-CoA, linking glycolysis to the TCA cycle
What effect does arsenic have on pyruvate dehydrogenase
Arsenic inhibits the pyruvate dehydrogenase complex by binding to dihydrolipoamide, leading to reduced activity and lactic acidosis
What is the result of a deficiency in glucose-6-phosphate dehydrogenase (G6PD)
G6PD deficiency leads to hemolytic anemia, especially under oxidative stress, due to impaired NADPH production
What are the key points to remember about the TCA cycle
The TCA cycle generates NADH and FADH2 for the electron transport chain, produces GTP/ATP, and is crucial for energy production
What are the effects of electron transport chain (ETC) uncoupling
ETC uncoupling dissipates the proton gradient as heat, reducing ATP production and increasing thermogenesis
What are the key inhibitors of Complex I in the ETC
Rotenone and Amytal
What are the key enzymes that circumvent gluconeogenesis
Pyruvate carboxylase, PEPCK, fructose-1,6-bisphosphatase, and glucose-6-phosphatase
What is the significance of fructose 2,6-bisphosphate in metabolism
Fructose 2,6-bisphosphate regulates glycolysis and gluconeogenesis, activated by insulin and inhibited by glucagon
What is the role of insulin in glycogen metabolism
Insulin stimulates glycogen synthesis and inhibits glycogenolysis
What are the primary effects of glucagon and epinephrine on glycogen metabolism
Both hormones stimulate glycogenolysis and inhibit glycogen synthesis
What is the role of fatty acid synthase
Fatty acid synthase catalyzes the synthesis of fatty acids from acetyl-CoA and malonyl-CoA in the cytoplasm
What is the impact of a deficiency in medium-chain acyl-CoA dehydrogenase (MCAD)
MCAD deficiency leads to hypoglycemia and the accumulation of medium-chain fatty acids during fasting or illness
What enzyme is deficient in phenylketonuria (PKU)
Phenylalanine hydroxylase
What are the symptoms of maple syrup urine disease (MSUD)
Sweet-smelling urine, lethargy, poor feeding, vomiting, and developmental delay
What causes hyperammonemia in urea cycle disorders
Deficiencies in enzymes like ornithine transcarbamylase (OTC) or carbamoyl phosphate synthetase (CPS) lead to the accumulation of ammonia
What is the function of carbamoyl phosphate synthetase I (CPS I) in the urea cycle
CPS I catalyzes the formation of carbamoyl phosphate from ammonia and bicarbonate, the first step in the urea cycle
What are the clinical features of ornithine transcarbamylase (OTC) deficiency
Hyperammonemia, orotic aciduria, lethargy, and cerebral edema
What is the role of lipoprotein lipase (LPL) in lipid metabolism
LPL hydrolyzes triglycerides in chylomicrons and VLDL into free fatty acids and glycerol, facilitating their uptake by tissues
What is the significance of ApoB-100 in lipoprotein metabolism
ApoB-100 is essential for the synthesis and clearance of VLDL, IDL, and LDL
What are the clinical features of familial hypercholesterolemia
Elevated LDL cholesterol, tendon xanthomas, and an increased risk of atherosclerosis
What is the impact of statins on cholesterol synthesis
Statins inhibit HMG-CoA reductase, reducing cholesterol synthesis and increasing LDL clearance from the bloodstream
What are the consequences of uncoupling protein (UCP) activity
UCPs dissipate the proton gradient in mitochondria, leading to heat generation instead of ATP production
What is the main source of energy during the fed state
Glucose is the main source of energy during the fed state
What are the key metabolic pathways activated during the fed state
Glycolysis, glycogenesis, and lipogenesis are activated during the fed state
What is the role of insulin in the fed state
Insulin promotes glucose uptake, glycogen synthesis, and fat storage, while inhibiting gluconeogenesis and glycogenolysis
How does the liver respond to insulin during the fed state
The liver increases glycogen synthesis and decreases glucose production through gluconeogenesis
What is the primary function of the pentose phosphate pathway
The pentose phosphate pathway generates NADPH and ribose-5-phosphate for nucleotide synthesis and reductive biosynthesis
What are the key enzymes of the pentose phosphate pathway
Glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase are key enzymes of the pentose phosphate pathway
What happens during the oxidative phase of the pentose phosphate pathway
NADPH is generated, which is essential for fatty acid synthesis and maintaining reduced glutathione levels
What is the role of NADPH in red blood cells
NADPH is crucial for maintaining reduced glutathione levels, which protect red blood cells from oxidative damage
What triggers the non-oxidative phase of the pentose phosphate pathway
The non-oxidative phase is triggered when the cell needs ribose-5-phosphate for nucleotide synthesis
What is the impact of a deficiency in glucose-6-phosphate dehydrogenase (G6PD)
G6PD deficiency leads to reduced NADPH production, making red blood cells more susceptible to oxidative stress and hemolysis
What is the role of fructose-2,6-bisphosphate in glycolysis
Fructose-2,6-bisphosphate activates phosphofructokinase-1 (PFK-1), enhancing glycolysis
How is fructose-2,6-bisphosphate regulated
Fructose-2,6-bisphosphate levels are regulated by insulin (which increases it) and glucagon (which decreases it)
What is the function of pyruvate dehydrogenase (PDH) in energy metabolism
PDH converts pyruvate to acetyl-CoA, linking glycolysis to the TCA cycle
What regulates pyruvate dehydrogenase activity
PDH is activated by ADP and inhibited by ATP, NADH, and acetyl-CoA
What is the role of the TCA cycle in cellular respiration
The TCA cycle generates NADH and FADH2, which are used in the electron transport chain to produce ATP
What are the key products of one turn of the TCA cycle
One turn of the TCA cycle produces 3 NADH, 1 FADH2, 1 GTP (or ATP), and 2 CO2 molecules
What is the importance of alpha-ketoglutarate in the TCA cycle
Alpha-ketoglutarate is a key intermediate that can be used for amino acid synthesis and energy production
What enzyme converts succinate to fumarate in the TCA cycle
Succinate dehydrogenase converts succinate to fumarate, and it is also part of Complex II in the electron transport chain
What is the role of citrate in metabolism
Citrate can be used in the TCA cycle, or transported to the cytoplasm for fatty acid and cholesterol synthesis
What is the significance of the malate-aspartate shuttle
The malate-aspartate shuttle transfers reducing equivalents (NADH) from the cytoplasm into the mitochondria for ATP production
What is the function of the electron transport chain (ETC)
The ETC transfers electrons from NADH and FADH2 to oxygen, driving the synthesis of ATP through oxidative phosphorylation
What is the role of Complex IV in the electron transport chain
Complex IV (cytochrome c oxidase) transfers electrons to oxygen, the final electron acceptor, forming water
Pumps protons
What happens during oxidative phosphorylation
During oxidative phosphorylation, the energy from electron transfer in the ETC is used to pump protons across the mitochondrial membrane, creating a gradient that drives ATP synthesis
What are the effects of ETC uncoupling on cellular metabolism
ETC uncoupling dissipates the proton gradient as heat, reducing ATP production and increasing thermogenesis
What is the function of ATP synthase in mitochondria
ATP synthase uses the proton gradient generated by the ETC to convert ADP and inorganic phosphate into ATP
What are the consequences of a deficiency in pyruvate dehydrogenase (PDH)
PDH deficiency leads to lactic acidosis, neurodevelopmental delay, and decreased energy production
What role does the enzyme hexokinase play in glycolysis
Hexokinase phosphorylates glucose to form glucose-6-phosphate, the first step in glycolysis
What is the function of phosphofructokinase-1 (PFK-1) in glycolysis
PFK-1 is the rate-limiting enzyme in glycolysis, converting fructose-6-phosphate to fructose-1,6-bisphosphate
What activates and inhibits phosphofructokinase-1 (PFK-1)
PFK-1 is activated by AMP and fructose-2,6-bisphosphate and inhibited by ATP and citrate
What is the role of pyruvate kinase in glycolysis
Pyruvate kinase catalyzes the final step in glycolysis, converting phosphoenolpyruvate (PEP) to pyruvate and generating ATP
What are the key regulatory enzymes of gluconeogenesis
Pyruvate carboxylase, PEPCK, fructose-1,6-bisphosphatase, and glucose-6-phosphatase are key enzymes in gluconeogenesis
What is the function of glucose-6-phosphatase in gluconeogenesis
Glucose-6-phosphatase converts glucose-6-phosphate to glucose, allowing it to be released into the bloodstream
What are the effects of insulin on gluconeogenesis
Insulin inhibits gluconeogenesis by decreasing the expression of key gluconeogenic enzymes
What role does glucagon play in gluconeogenesis
Glucagon promotes gluconeogenesis by increasing the expression of enzymes like PEPCK and glucose-6-phosphatase
What is the role of acetyl-CoA in fatty acid synthesis
Acetyl-CoA provides the two-carbon units for fatty acid synthesis, which occurs in the cytoplasm
What enzyme is responsible for the synthesis of malonyl-CoA
Acetyl-CoA carboxylase catalyzes the formation of malonyl-CoA from acetyl-CoA
What is the function of fatty acid synthase
Fatty acid synthase catalyzes the synthesis of palmitate (a 16-carbon saturated fatty acid) from acetyl-CoA and malonyl-CoA
What is the impact of insulin on fatty acid synthesis
Insulin promotes fatty acid synthesis by activating acetyl-CoA carboxylase and increasing the availability of glucose for lipogenesis
What happens to fatty acids during beta-oxidation
During beta-oxidation, fatty acids are broken down in the mitochondria to produce acetyl-CoA, NADH, and FADH2
What regulates the rate of beta-oxidation in the mitochondria
The rate of beta-oxidation is regulated by the availability of fatty acids and the activity of carnitine palmitoyltransferase I (CPT I)
What is the role of carnitine in fatty acid metabolism
Carnitine transports long-chain fatty acids into the mitochondria for beta-oxidation
What is the function of hormone-sensitive lipase (HSL)
HSL hydrolyzes stored triglycerides in adipose tissue into free fatty acids and glycerol, which are released into the bloodstream
What triggers the activation of hormone-sensitive lipase (HSL)
HSL is activated by epinephrine and glucagon during fasting or stress, leading to the mobilization of stored fats
What is the role of ketone bodies during fasting
Ketone bodies provide an alternative energy source, particularly for the brain, during prolonged fasting
What are the three main ketone bodies produced during ketogenesis
The three main ketone bodies are acetoacetate, beta-hydroxybutyrate, and acetone
What happens to ketone bodies during prolonged fasting
During prolonged fasting, ketone bodies accumulate and are used by the brain and other tissues for energy, sparing glucose
What is the impact of a deficiency in medium-chain acyl-CoA dehydrogenase (MCAD)
MCAD deficiency impairs fatty acid oxidation, leading to hypoglycemia and the accumulation of medium-chain fatty acids
What is the role of the urea cycle in nitrogen metabolism
The urea cycle converts toxic ammonia into urea, which is then excreted in the urine
What enzyme catalyzes the first step of the urea cycle
Carbamoyl phosphate synthetase I (CPS I) catalyzes the first step of the urea cycle, forming carbamoyl phosphate from ammonia and bicarbonate
What are the symptoms of a urea cycle disorder
Symptoms include hyperammonemia, lethargy, vomiting, seizures, and, if untreated, can lead to coma or death
What is the significance of N-acetylglutamate in the urea cycle
N-acetylglutamate is an allosteric activator of carbamoyl phosphate synthetase I (CPS I), the first enzyme in the urea cycle
What is the effect of a deficiency in ornithine transcarbamylase (OTC)
OTC deficiency leads to hyperammonemia and elevated orotic acid levels, causing neurological damage and developmental delays
What is the role of alanine in the transport of nitrogen
Alanine transports nitrogen from muscle tissue to the liver, where it is converted to urea for excretion
What happens to amino acids during prolonged fasting
During prolonged fasting, amino acids are released from muscle protein and used for gluconeogenesis and energy production
What is the function of glutamine in nitrogen metabolism
Glutamine carries ammonia from peripheral tissues to the liver or kidneys for excretion as urea or ammonium
What is the significance of the Cori cycle in metabolism
The Cori cycle allows lactate produced by anaerobic glycolysis in muscles to be converted back to glucose in the liver
What is the role of phenylalanine hydroxylase in amino acid metabolism
Phenylalanine hydroxylase converts phenylalanine to tyrosine, a precursor for neurotransmitters and melanin
What is the consequence of a deficiency in phenylalanine hydroxylase
A deficiency in phenylalanine hydroxylase leads to phenylketonuria (PKU), causing the accumulation of phenylalanine and resulting in intellectual disability if untreated
What are the key symptoms of phenylketonuria (PKU)
Symptoms of PKU include intellectual disability, musty body odor, fair skin, eczema, and seizures
What is the treatment for phenylketonuria (PKU)
Treatment for PKU involves a low-phenylalanine diet and supplementation with tyrosine
What enzyme is deficient in maple syrup urine disease
Maple syrup urine disease is caused by a deficiency in the branched-chain alpha-keto acid dehydrogenase complex
What are the symptoms of maple syrup urine disease
Symptoms include sweet-smelling urine, poor feeding, vomiting, lethargy, and, in severe cases, neurological damage
What is the role of vitamin B6 in amino acid metabolism
Vitamin B6 (pyridoxine) acts as a cofactor for transaminases and other enzymes involved in amino acid metabolism
What enzyme deficiency causes homocystinuria
Homocystinuria is often caused by a deficiency in cystathionine beta-synthase
What are the clinical features of homocystinuria
Homocystinuria is characterized by marfanoid habitus, lens dislocation, thromboembolism, and intellectual disability
What is the difference between homocystinuria and Marfan syndrome
Homocystinuria features downward lens dislocation and increased risk of thrombosis, while Marfan syndrome features upward lens dislocation and aortic root dilation
What enzyme deficiency leads to alkaptonuria
Alkaptonuria is caused by a deficiency in homogentisate oxidase
What are the key symptoms of alkaptonuria
Symptoms of alkaptonuria include dark urine, ochronosis (bluish-black pigmentation of connective tissues), and arthritis
What is the role of branched-chain amino acids in metabolism
Branched-chain amino acids (valine, leucine, isoleucine) are important for protein synthesis and can be used as energy sources
What is the treatment approach for maple syrup urine disease
Treatment involves dietary restriction of branched-chain amino acids and supplementation with thiamine (vitamin B1)
What enzyme deficiency causes orotic aciduria
Orotic aciduria is caused by a deficiency in uridine monophosphate synthase (UMPS)
What distinguishes orotic aciduria from OTC deficiency
Orotic aciduria lacks hyperammonemia, while OTC deficiency is associated with elevated orotic acid and hyperammonemia
What are the treatment options for homocystinuria
Treatment includes a low-methionine diet, high-dose vitamin B6, and, if necessary, betaine to reduce homocysteine levels
What is the function of lipoprotein lipase (LPL)
Lipoprotein lipase hydrolyzes triglycerides in chylomicrons and VLDL into free fatty acids and glycerol, facilitating their uptake by tissues
What is the role of ApoB-100 in lipoprotein metabolism
ApoB-100 is necessary for the assembly and secretion of VLDL from the liver and is a ligand for the LDL receptor
What are the clinical features of familial hypercholesterolemia
Features include elevated LDL cholesterol, xanthomas (cholesterol deposits in tendons), and an increased risk of atherosclerosis and coronary artery disease
What is the impact of statins on cholesterol metabolism
Statins inhibit HMG-CoA reductase, reducing cholesterol synthesis and increasing the clearance of LDL from the bloodstream
What are the consequences of a deficiency in carnitine palmitoyltransferase I (CPT I)
CPT I deficiency impairs the transport of long-chain fatty acids into the mitochondria for beta-oxidation, leading to hypoglycemia and muscle weakness
What is the significance of ApoE in lipid metabolism
ApoE is crucial for the clearance of chylomicron remnants and VLDL remnants by the liver
What is the role of very low-density lipoprotein (VLDL) in lipid transport
VLDL transports triglycerides from the liver to peripheral tissues for energy use or storage
What happens to VLDL after triglyceride removal
VLDL is converted to intermediate-density lipoprotein (IDL) and eventually to low-density lipoprotein (LDL), which delivers cholesterol to tissues
What is the role of high-density lipoprotein (HDL) in cholesterol metabolism
HDL is involved in reverse cholesterol transport, carrying cholesterol from peripheral tissues back to the liver for excretion
What are the effects of cholesterol ester transfer protein (CETP) on HDL function
CETP transfers cholesterol esters from HDL to other lipoproteins, which can influence HDL’s role in reverse cholesterol transport
What is the impact of a deficiency in lecithin-cholesterol acyltransferase (LCAT)
LCAT deficiency leads to low levels of esterified cholesterol in HDL and can cause corneal opacities, anemia, and kidney dysfunction
What is the primary role of chylomicrons in lipid metabolism
Chylomicrons transport dietary triglycerides and cholesterol from the intestines to tissues for energy use or storage
What is the effect of niacin on lipid profiles
Niacin reduces triglycerides and LDL cholesterol while increasing HDL cholesterol
What is the role of the liver in lipoprotein metabolism
The liver synthesizes VLDL, converts IDL to LDL, and clears chylomicron remnants and HDL cholesterol from the blood
What is the function of hormone-sensitive lipase (HSL)
HSL hydrolyzes stored triglycerides in adipose tissue into free fatty acids and glycerol, which are released into the bloodstream
What triggers the activation of hormone-sensitive lipase (HSL)
HSL is activated by epinephrine and glucagon during fasting or stress, leading to the mobilization of stored fats
What is the significance of ApoB-48 in lipid transport
ApoB-48 is essential for the assembly and secretion of chylomicrons from the intestines
What enzyme catalyzes the conversion of cholesterol to pregnenolone
Cholesterol side-chain cleavage enzyme (CYP11A1) catalyzes the conversion of cholesterol to pregnenolone, the first step in steroid hormone synthesis
What is the role of acetyl-CoA in cholesterol synthesis
Acetyl-CoA is the precursor for cholesterol synthesis, which occurs in the cytoplasm and endoplasmic reticulum of liver cells
What are the main regulatory steps in cholesterol synthesis
The conversion of HMG-CoA to mevalonate by HMG-CoA reductase is the rate-limiting step and key regulatory point in cholesterol synthesis
What are the clinical implications of a deficiency in ApoB-100
A deficiency in ApoB-100 can lead to familial hypobetalipoproteinemia, characterized by low levels of LDL cholesterol and fat malabsorption
What is the function of bile acids in lipid digestion
Bile acids emulsify dietary fats in the intestines, aiding in the digestion and absorption of lipids
What happens to bile acids after they aid in digestion
Bile acids are reabsorbed in the ileum and recycled back to the liver through enterohepatic circulation
What is the role of lipoprotein(a) in cardiovascular disease
Lipoprotein(a) is a variant of LDL associated with an increased risk of atherosclerosis and cardiovascular disease
What are the effects of omega-3 fatty acids on lipid metabolism
Omega-3 fatty acids reduce triglyceride levels, have anti-inflammatory effects, and may reduce the risk of cardiovascular disease
What is the function of peroxisome proliferator-activated receptors (PPARs) in lipid metabolism
PPARs regulate the expression of genes involved in fatty acid oxidation, lipid storage, and insulin sensitivity
What are the clinical features of metabolic syndrome
Metabolic syndrome is characterized by abdominal obesity, insulin resistance, dyslipidemia, hypertension, and an increased risk of cardiovascular disease
What is the impact of insulin resistance on lipid metabolism
Insulin resistance leads to increased lipolysis, elevated free fatty acids, and dyslipidemia, contributing to cardiovascular risk
What is the role of leptin in energy homeostasis
Leptin regulates appetite and energy expenditure by signaling the status of energy stores to the hypothalamus
What are the effects of leptin deficiency
Leptin deficiency leads to uncontrolled appetite, obesity, and insulin resistance
What is the significance of adiponectin in metabolism
Adiponectin enhances insulin sensitivity, promotes fatty acid oxidation, and has anti-inflammatory effects
What are the consequences of low adiponectin levels
Low adiponectin levels are associated with insulin resistance, type 2 diabetes, and increased cardiovascular risk
What is the role of AMP-activated protein kinase (AMPK) in metabolism
AMPK promotes energy-producing pathways like glucose uptake and fatty acid oxidation, while inhibiting energy-consuming processes like lipogenesis
What triggers the activation of AMPK
AMPK is activated by an increase in the AMP/ATP ratio, indicating low energy status in the cell
What is the role of SREBP in cholesterol and fatty acid synthesis
Sterol regulatory element-binding proteins (SREBPs) enhance the transcription of genes involved in cholesterol and fatty acid synthesis
What is the function of choline in lipid metabolism
Choline is required for the synthesis of phosphatidylcholine, a major component of cell membranes and lipoproteins
What are the consequences of choline deficiency
Choline deficiency can lead to liver damage, muscle dysfunction, and non-alcoholic fatty liver disease (NAFLD)
What enzyme deficiency causes Niemann-Pick disease
Niemann-Pick disease is caused by a deficiency in sphingomyelinase, leading to the accumulation of sphingomyelin in cells
What are the key features of Gaucher disease
Gaucher disease is characterized by hepatosplenomegaly, bone pain, anemia, and the accumulation of glucocerebrosides in macrophages
What is the treatment approach for Gaucher disease
Treatment includes enzyme replacement therapy with recombinant glucocerebrosidase and, in some cases, substrate reduction therapy
What enzyme deficiency leads to Tay-Sachs disease
Tay-Sachs disease is caused by a deficiency in hexosaminidase A, leading to the accumulation of GM2 gangliosides in neurons
What are the clinical manifestations of Tay-Sachs disease
Symptoms include progressive neurodegeneration, cherry-red spots on the macula, and loss of motor skills
What is the role of ceramide in sphingolipid metabolism
Ceramide is a central molecule in sphingolipid metabolism, serving as a precursor for sphingomyelin and glycosphingolipids
What are the consequences of a deficiency in arylsulfatase A
A deficiency in arylsulfatase A leads to metachromatic leukodystrophy, characterized by the accumulation of sulfatides and progressive demyelination
What is the function of lysosomal acid lipase
Lysosomal acid lipase hydrolyzes cholesteryl esters and triglycerides within lysosomes, playing a crucial role in cholesterol metabolism
What enzyme deficiency causes Krabbe disease
Krabbe disease is caused by a deficiency in galactocerebrosidase, leading to the accumulation of galactocerebrosides and psychosine in the nervous system
What are the key features of Krabbe disease
Symptoms include developmental delay, optic atrophy, peripheral neuropathy, and early death
What is the impact of a deficiency in alpha-galactosidase A
A deficiency in alpha-galactosidase A causes Fabry disease, characterized by angiokeratomas, kidney failure, and neuropathic pain
What is the role of glucocerebrosidase in lipid metabolism
Glucocerebrosidase breaks down glucocerebrosides into glucose and ceramide, preventing their accumulation in cells
What is the clinical significance of lysosomal storage diseases
Lysosomal storage diseases result from deficiencies in enzymes required for the degradation of specific biomolecules, leading to their accumulation and causing cellular dysfunction and disease
