Podcast
Questions and Answers
What is produced during the oxidative phase of the Pentose Phosphate Pathway?
What is produced during the oxidative phase of the Pentose Phosphate Pathway?
Which statement correctly describes glycolysis?
Which statement correctly describes glycolysis?
Which pathway is primarily responsible for generating NADPH?
Which pathway is primarily responsible for generating NADPH?
What is the end product of glycolysis under anaerobic conditions?
What is the end product of glycolysis under anaerobic conditions?
Signup and view all the answers
In the Pentose Phosphate Pathway, what does the nonoxidative phase regenerate?
In the Pentose Phosphate Pathway, what does the nonoxidative phase regenerate?
Signup and view all the answers
What is the role of hexokinase in relation to glucose affinity?
What is the role of hexokinase in relation to glucose affinity?
Signup and view all the answers
What does a high Km value indicate about an enzyme's affinity?
What does a high Km value indicate about an enzyme's affinity?
Signup and view all the answers
How does the increase in reactants affect product formation?
How does the increase in reactants affect product formation?
Signup and view all the answers
What are the possible fates of pyruvate under anaerobic conditions?
What are the possible fates of pyruvate under anaerobic conditions?
Signup and view all the answers
Which molecule must be reoxidized for glycolysis to continue?
Which molecule must be reoxidized for glycolysis to continue?
Signup and view all the answers
What is the primary purpose of gluconeogenesis?
What is the primary purpose of gluconeogenesis?
Signup and view all the answers
What happens when there is an increase in product concentration?
What happens when there is an increase in product concentration?
Signup and view all the answers
What is the result of using ATP in the cell during energy-requiring processes?
What is the result of using ATP in the cell during energy-requiring processes?
Signup and view all the answers
What is the primary reason glucose-dependent cells, such as RBCs, cannot undergo oxidative phosphorylation?
What is the primary reason glucose-dependent cells, such as RBCs, cannot undergo oxidative phosphorylation?
Signup and view all the answers
How does glucagon affect fructose 2,6-bisphosphate levels during fasting?
How does glucagon affect fructose 2,6-bisphosphate levels during fasting?
Signup and view all the answers
Why can't the brain utilize amino acids during prolonged fasting?
Why can't the brain utilize amino acids during prolonged fasting?
Signup and view all the answers
What triggers gluconeogenesis when glucose levels are low?
What triggers gluconeogenesis when glucose levels are low?
Signup and view all the answers
Which of the following is a precursor for gluconeogenesis?
Which of the following is a precursor for gluconeogenesis?
Signup and view all the answers
What role do glucogenic amino acids play in metabolism?
What role do glucogenic amino acids play in metabolism?
Signup and view all the answers
Why can animals not convert fatty acids into glucose?
Why can animals not convert fatty acids into glucose?
Signup and view all the answers
Which steps in glycolysis are irreversible and cannot be easily reversed for gluconeogenesis?
Which steps in glycolysis are irreversible and cannot be easily reversed for gluconeogenesis?
Signup and view all the answers
In which part of the body does gluconeogenesis primarily occur?
In which part of the body does gluconeogenesis primarily occur?
Signup and view all the answers
During the energy use of the heart muscle, what is expected to activate phosphofructokinase 1?
During the energy use of the heart muscle, what is expected to activate phosphofructokinase 1?
Signup and view all the answers
Which enzyme is primarily responsible for the conversion of pyruvate to oxaloacetate?
Which enzyme is primarily responsible for the conversion of pyruvate to oxaloacetate?
Signup and view all the answers
Which compound cannot be synthesized from acetyl-CoA in animals?
Which compound cannot be synthesized from acetyl-CoA in animals?
Signup and view all the answers
What is a significant disadvantage of gluconeogenesis?
What is a significant disadvantage of gluconeogenesis?
Signup and view all the answers
During gluconeogenesis, which compound is NOT an end product?
During gluconeogenesis, which compound is NOT an end product?
Signup and view all the answers
What is the main reason that gluconeogenesis is not simply a reversal of glycolysis?
What is the main reason that gluconeogenesis is not simply a reversal of glycolysis?
Signup and view all the answers
Which of the following statements about ATP generation in gluconeogenesis is true?
Which of the following statements about ATP generation in gluconeogenesis is true?
Signup and view all the answers
Which of the following amino acids are classified as glucogenic?
Which of the following amino acids are classified as glucogenic?
Signup and view all the answers
What is the primary role of glycerokinase in gluconeogenesis?
What is the primary role of glycerokinase in gluconeogenesis?
Signup and view all the answers
Which of the following statements about Acetyl-CoA is correct?
Which of the following statements about Acetyl-CoA is correct?
Signup and view all the answers
What metabolic pathway is activated by fructose-1,6-bisphosphatase?
What metabolic pathway is activated by fructose-1,6-bisphosphatase?
Signup and view all the answers
Which cofactor is necessary for propionyl CoA carboxylase to function?
Which cofactor is necessary for propionyl CoA carboxylase to function?
Signup and view all the answers
Which of the following is true regarding the regulation of gluconeogenesis?
Which of the following is true regarding the regulation of gluconeogenesis?
Signup and view all the answers
What is the end product of the conversion of methyl malonyl CoA in gluconeogenesis?
What is the end product of the conversion of methyl malonyl CoA in gluconeogenesis?
Signup and view all the answers
How is glycerol converted into an intermediate that can enter glycolysis?
How is glycerol converted into an intermediate that can enter glycolysis?
Signup and view all the answers
Study Notes
Lactic Acid Fermentation
- Involves the conversion of carbohydrates into lactic acid, primarily by certain bacteria and fungi.
- Plays a critical role in energy production under anaerobic conditions.
Cori Cycle
- A metabolic pathway that recycles lactate produced during anaerobic glycolysis back to glucose in the liver.
Pentose Phosphate Pathway (PPP)
- Functions as an alternative to glycolysis, generating NADPH and ribose-5-phosphate for nucleotide synthesis.
- Two main phases:
- Oxidative phase produces NADPH and a pentose sugar.
- Non-oxidative phase regenerates glucose-6-phosphate from ribose-5-phosphate.
- Significant connection to NADPH in combating oxidative stress.
- Clinical relevance highlighted by glucose-6-phosphate dehydrogenase (G6PD) deficiency.
Glycolysis Review
- Central metabolic pathway for glucose oxidation across all tissues, yielding approximately -2840 kJ/mol of energy.
- Glucose is essential for energy production and serves as a precursor for various metabolic pathways.
- Results in the production of pyruvate as the end product.
- Key outputs include:
- 4 ATP, needed for energy-requiring cellular processes.
- 2 NADH, which must be reoxidized to continue glycolysis.
Regulation of Glycolysis
- Heavily regulated to ensure effective nutrient use and ATP production.
- Hexokinase is characterized by higher affinity for glucose; high Km values indicate low affinity.
Gluconeogenesis
- Synthesizes glucose from non-carbohydrate precursors to supply glucose-dependent cells (e.g., RBCs).
- Vital during prolonged fasting, particularly for brain function which relies predominantly on glucose.
- Energetically expensive, operating primarily in the liver.
Pyruvate Fates
- Under anaerobic conditions, pyruvate can convert to either lactate or ethanol (not in humans).
- Transformation of pyruvate is contingent on environmental oxygen levels.
Gluconeogenesis Precursors
- Uses lactate, pyruvate, and oxaloacetate as substrates.
- Glucogenic amino acids contribute by entering the citric acid cycle.
- Fatty acids cannot be converted into glucose due to their metabolism producing acetyl-CoA, which cannot yield oxaloacetate.
Differences Between Glycolysis and Gluconeogenesis
- Their pathways are thermodynamically favorable, but they operate in reverse directions.
- Involves several key enzymes that facilitate irreversible steps of glycolysis to form glucose.
Enzymes in Gluconeogenesis
- Notable enzymes include:
- Pyruvate carboxylase converts pyruvate to oxaloacetate.
- Phosphoenolpyruvate carboxykinase (PEPCK) further converts oxaloacetate to phosphoenolpyruvate.
- Fructose-1,6-bisphosphatase regulates the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate.
Reciprocal Regulation
- Generally regulated by fluctuations in metabolites; increases in reactants stimulate product formation, while increases in products can inhibit further synthesis.
- Key regulatory elements include citrate (activating gluconeogenesis) and AMP (inhibiting it), reflecting energy status in the cell.
Additional Gluconeogenesis Sources
- Glycerol, released from adipose tissue, can be converted to glucose; the process includes enzymes like glycerokinase and glycerol-3-phosphate dehydrogenase.
- Propionate from odd-chain fatty acids and certain amino acids can also enter gluconeogenesis through conversion to succinyl-CoA before producing glucose.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on lactic acid fermentation, the Cori Cycle, and the Pentose Phosphate Pathway. This quiz covers the major metabolic pathways of glucose and their importance in organisms. Dive into the details of oxidative and nonoxidative phases, including their roles in generating NADPH.
