Ketogenesis Flashcards
What are the names of the ketone bodies produced via ketogenesis? How is the third ketone body created?
Beta-hydroxybutyrate
Acetoacetate
The third ketone body is acetone which is the breakdown product of acetoacetate.
Why are ketone bodies required in an individual who is obtaining enough energy from the other macromolecules (carbohydrates, lipid and protein)?
Ketone bodies can be metabolized by the brain as a backup energy source. This is important as the brain can only derive energy from glucose, not lipid (fatty acids).
Multiple acetyl CoA are needed to begin ketogenesis. However, acetyl CoA are preferentially used for the CAC in preparation for making a lot of ATP (in ETC/OP).
What metabolic process would acetyl CoA be used for if it could not be processed by the CAC (due to a blockage)?
When acetyl CoA are not being used for the CAC due to a blockage, more of the acetyl CoA are used to make ketone bodies via ketogenesis.
Untreated diabetics are at risk of ketosis and even ketoacidosis due to very high numbers of ketone bodies in the blood. Untreated diabetics can not bring glucose inside the cell, as they are unable to respond to insulin. Explain this phenomenon by answering the following questions:
If glucose can not enter the cell (due to a faulty response to insulin) is glucose available inside the cell to be metabolised in glycolysis? Why/why not?
If glucose is not brought into the cell due to a faulty response to the insulin hormone then there is no glucose to begin metabolic processes that require glucose as the input e.g. glycolysis.
Pyruvate (product of glycolysis) can be converted to oxaloacetate which is one of the reactants needed to begin the CAC. Would an untreated diabetic have oxaloacetate available to begin the CAC? Why/why not?
No glycolysis performed due to a lack of glucose inside the cell.
Pyruvate product is not being made and therefore is not available to be converted into oxaloacetate.
Why is a lot of acetyl CoA (produced from lipid metabolism) used to produce ketone bodies in untreated diabetics rather than entering the CAC, as acetyl CoA does in healthy individuals?
Without oxaloacetate available to begin the CAC, there is a build-up of acetyl CoA that untreated diabetics can not use to produce energy. Instead the acetyl CoA is used to create ketone bodies via ketogenesis.
What are the health problems associated with having a very large amount of ketone bodies in the blood? Could this be deadly? Explain.
The accumulation of ketone bodies in the blood firstly leads to ketosis and in more extreme cases ketoacidosis.
Ketone bodies are acidic, so having so many ketone bodies in the blood lowers the pH of the blood. If not corrected quickly ketoacidosis can lead to coma and death.
