Flashcards in this deck (108)

• What are the sources of dietary glucose?

  Starch, monosaccharides, disaccharides, glucose.
  biochemistry glucose
• What stimulates insulin secretion?

  Ingestion of glucose.
  biochemistry insulin
• What does insulin do to GLUT4?

  Increases GLUT4 on cell surfaces.
  biochemistry insulin
• What happens to glucose in cells?

  Phosphorylated, undergoes glycolysis, or stored as glycogen.
  biochemistry glucose
• What is the role of glycogen?

  Storage form of glucose for rapid response to low blood glucose.
  biochemistry glycogen
• How much glycogen is stored in muscle?

  About 400g.
  biochemistry glycogen
• How much glycogen is stored in the liver?

  About 75g.
  biochemistry glycogen
• What is gluconeogenesis?

  Synthesis of glucose from non-carbohydrate sources.
  biochemistry gluconeogenesis
• What is glycogen composed of?

  Extensively branched homopolysaccharide of glucose units.
  biochemistry glycogen
• What type of bonds form the main chain of glycogen?

  α(1,4) bonds.
  biochemistry glycogen
• What type of bonds create branches in glycogen?

  α(1,6) bonds.
  biochemistry glycogen
• Why is glycogen highly branched?

  Allows rapid glucose release.
  biochemistry glycogen
• What is the role of non-reducing ends in glycogen?

  Sites for rapid glucose cleavage by enzymes.
  biochemistry glycogen
• What is required to add glucose to glycogen?

  UDP-glucose formation.
  biochemistry glycogen
• What happens during liver glycogen degradation?

  Glycogen is broken down into glucose-1-phosphate (G-1-P).
  biochemistry glycogen
• What does G-1-P convert to in the liver?

  Glucose-6-phosphate (G-6-P).
  biochemistry glycogen
• What does G-6-P convert to in the liver?

  Glucose, released into the bloodstream.
  biochemistry glycogen
• How does the liver gain energy?

  Primarily from fatty acid oxidation.
  biochemistry liver
• What happens to muscle glycogen during degradation?

  Converted to G-1-P, then G-6-P, enters glycolysis.
  biochemistry glycogen
• How is liver glycogen affected during fasting?

  Increases during well-fed state, depleted during fasting.
  biochemistry glycogen
• How does muscle glycogen respond to fasting?

  Not significantly affected by short fasting, moderately decreased during prolonged fasting.
  biochemistry glycogen
• Where does glycogen degradation start?

  At the non-reducing ends.
  biochemistry glycogen
• What enzyme breaks down α(1,4) bonds in glycogen?

  Glycogen phosphorylase.
  biochemistry glycogen
• What is limit dextrin?

  A short chain left by glycogen phosphorylase near α(1,6) branch points.
  biochemistry glycogen
• What are the two functions of the de-branching enzyme?

  Transferase activity and α(1,6) glycosidase activity.
  biochemistry glycogen
• What is the lysosomal enzyme that degrades glycogen?

  α(1−4)-glucosidase (acid maltase)
  biochemistry glycogen
• What disease is caused by α(1−4)-glucosidase deficiency?

  Type II Glycogen Storage Disease (Pompe Disease)
  disease glycogen
• Which organs are primarily affected by Pompe Disease?

  Liver, heart, and muscle
  anatomy disease
• What is the main building block for glycogen synthesis?

  Glucose units
  biochemistry glycogen
• What is UDP-glucose formed from?

  Glucose-1-phosphate and UTP
  biochemistry glycogen
• What enzyme converts glucose-6-phosphate to glucose-1-phosphate?

  Phosphoglucomutase
  biochemistry glycogen
• What initiates glycogen synthesis?

  UDP-glucose attaches to glycogenin
  biochemistry glycogen
• What enzyme adds glucose units to elongate the glycogen chain?

  Glycogen synthase
  biochemistry glycogen
• What enzyme forms branches in glycogen?

  Branching enzyme (4:6-transferase)
  biochemistry glycogen
• What is the purpose of glycogen branching?

  Allows rapid mobilization of glucose
  biochemistry glycogen
• What are glycogen storage diseases (GSDs)?

  Genetic disorders from enzyme defects in glycogen metabolism
  disease glycogen
• What is the enzyme deficiency in Von Gierke Disease?

  Glucose-6-phosphatase
  disease glycogen
• Which organs are affected by Von Gierke Disease?

  Liver, kidneys, and intestines
  anatomy disease
• What are the symptoms of Von Gierke Disease?

  Severe fasting hypoglycemia, hepatomegaly, renal disease
  symptoms disease
• What is the enzyme deficiency in McArdle Syndrome?

  Muscle glycogen phosphorylase
  disease glycogen
• What are the symptoms of McArdle Syndrome?

  Muscle weakness, cramping after exercise
  symptoms disease
• What is the enzyme deficiency in Pompe Disease?

  Lysosomal α(1→4) glucosidase
  disease glycogen
• What are the symptoms of Pompe Disease?

  Glycogen accumulation in lysosomes, massive cardiomegaly
  symptoms disease
• What is a symptom of Pompe disease?

  Accumulation of glycogen in abnormal vacuoles within lysosomes
  pompe_disease symptoms
• What is massive cardiomegaly?

  Enlarged heart
  cardiology symptoms
• What are normal blood sugar levels in Pompe disease?

  Normal
  pompe_disease blood_sugar
• What is a consequence of Pompe disease?

  Early death from heart failure
  pompe_disease consequences
• What is the glycogen structure in Pompe disease?

  Normal, but excessively accumulated in lysosomes
  pompe_disease glycogen_structure
• What is the net reaction for glycogen synthesis?

  Glucose + ATP + UTP + Glycogen(n) → ADP + UDP + 2 Pi + Glycogen(n+1)
  glycogen_metabolism synthesis
• How many ATP molecules are consumed for each glucose added to glycogen?

  Approximately 2 ATP molecules
  glycogen_metabolism atp_consumption
• What is the net reaction for glycogen degradation?

  Glycogen(n) + Pi → Glycogen(n-1) + Glucose-1-phosphate
  glycogen_metabolism degradation
• When does glycogen synthesis occur?

  During the feeding state
  glycogen_metabolism synthesis
• What hormone promotes glycogen synthesis?

  Insulin
  hormones glycogen_synthesis
• When does glycogen degradation occur?

  During fasting
  glycogen_metabolism degradation
• What hormones stimulate glycogen degradation?

  Glucagon and epinephrine
  hormones glycogen_degradation
• What receptors do glucagon and epinephrine bind to?

  G-protein coupled receptors (GPCRs)
  hormones receptors
• What happens when glucagon binds to its GPCR?

  Activates associated G-protein
  hormones gpcr
• What does adenylyl cyclase convert ATP to?

  Cyclic AMP (cAMP)
  camp metabolism
• What does cAMP activate?

  Protein Kinase A (PKA)
  camp pka
• What does PKA regulate?

  Glycolysis and gluconeogenesis
  pka regulation
• What does PKA phosphorylation inhibit?

  Pyruvate kinase and glycogen synthase
  pka inhibition
• What does activated Glycogen Phosphorylase do?

  Catalyzes the breakdown of glycogen into glucose-1-phosphate
  glycogen_degradation enzyme
• What role does phosphorylation play in glycogen metabolism?

  Critical for activation and inhibition of enzymes
  phosphorylation glycogen_metabolism
• What promotes glycogen synthesis in the well-fed state?

  High insulin levels
  hormones glycogen_synthesis
• What does insulin inhibit?

  Glycogen degradation
  insulin regulation
• What promotes glycogen synthesis?

  High insulin levels
  glycogen synthesis insulin
• What does insulin activate to inhibit glycogen degradation?

  Phosphodiesterase
  insulin glycogen degradation
• What does phosphodiesterase degrade?

  cAMP to 5'-AMP
  phosphodiesterase camp
• What is the effect of reduced cAMP levels?

  Decreased activation of Protein Kinase A (PKA)
  camp pka
• What does insulin activate to dephosphorylate glycogen phosphorylase kinase?

  Protein phosphatases
  insulin glycogen phosphatases
• What enzyme is responsible for glycogen synthesis?

  Glycogen synthase
  glycogen synthesis enzyme
• What acts as an inhibitor of glycogen degradation in the liver?

  Glucose-6-Phosphate (G6P)
  liver glycogen g6p
• What inhibits glycogen degradation via feedback inhibition?

  Glucose
  glucose glycogen degradation
• What indicates a high-energy state and inhibits glycogen degradation?

  ATP
  atp glycogen energy
• What is the role of G6P in muscle regarding glycogen metabolism?

  Inhibits glycogen degradation and activates glycogen synthesis
  muscle glycogen g6p
• What does calcium (Ca²⁺) promote during muscle contraction?

  Glycogen degradation
  calcium muscle glycogen
• What does high AMP indicate in muscle cells?

  Low energy
  amp muscle energy
• What dual role does phosphorylation play in glycogen metabolism?

  Inhibition of glycogen synthase and activation of glycogen phosphorylase
  phosphorylation glycogen metabolism
• What ensures glycogen metabolism responds to energy needs?

  Allosteric Regulation
  glycogen metabolism regulation
• What triggers calcium release during muscle contraction?

  Nerve impulses
  calcium muscle contraction
• What complex is formed when calcium binds to calmodulin?

  Ca²⁺-Calmodulin Complex
  calcium calmodulin complex
• What does the active Ca²⁺-calmodulin complex activate?

  Glycogen phosphorylase kinase
  calmodulin glycogen activation
• What do GPCRs activate in glycogen metabolism?

  Adenylyl cyclase
  gpcr glycogen adenylyl_cyclase
• What second messenger is produced by adenylyl cyclase?

  cAMP
  adenylyl_cyclase camp messenger
• What activates GPCRs in glycogen metabolism?

  Hormones like epinephrine
  glycogen metabolism hormones
• What does cAMP activate in glycogen degradation?

  Protein Kinase A (PKA)
  glycogen degradation camp
• What does phospholipase C degrade?

  Phosphatidylinositol bisphosphate (PIP2)
  phospholipase pip2
• What are the products of PIP2 degradation?

  Diacylglycerol (DAG) and inositol trisphosphate (IP3)
  pip2 dag ip3
• What does IP3 bind to?

  IP3-gated calcium channels
  ip3 calcium channels
• What complex is formed by released calcium?

  Ca²⁺-calmodulin complex
  calcium calmodulin
• What does the Ca²⁺-calmodulin complex activate?

  Glycogen phosphorylase kinase and calmodulin-dependent protein kinase
  calmodulin kinase
• What inactivates glycogen synthase?

  Phosphorylation
  glycogen synthase phosphorylation
• Which hormones regulate glycogen synthase via GPCR and cAMP?

  Glucagon and Epinephrine
  glycogen synthase hormones
• What activates Protein Kinase A?

  cAMP
  pka camp
• What activates calmodulin-dependent protein kinase?

  Ca²⁺-calmodulin complex
  calmodulin kinase
• What activates Protein Kinase C?

  Calcium and DAG
  pkc calcium dag
• What role does calcium serve in muscle cells?

  Central regulator activating enzymes for glycogen degradation
  calcium muscle degradation
• What is a key regulatory mechanism for glycogen metabolism?

  Phosphorylation
  regulation glycogen phosphorylation
• What ensures a balanced response to metabolic needs?

  Multiple signaling pathways converge
  metabolism signaling balance
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