Term
| Glycolysis is regulated on what three levels? |
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Definition
Hexokinase, Glucokinase
Phosphofructokinase-1 (PFK1)
Pyruvate Kinase |
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Term
| Gluconeogenesis is regulated on what three levels? |
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Definition
Substrate availability (amino acid [alanine] and lactate)
Pyruvate Carboxylase
Fructose 1,6 Bisphosphatase |
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Term
| Why is the first step of glycolysis phosphorylation of the glucose molecule? |
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Definition
| Phosphorylated glucose cannot leave the cell, is essentially trapped |
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Term
| What are the general pathways of metabolic regulation? |
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Definition
Between cells
Within cells
via Secondary messengers |
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Term
| Intracellular regulation is done in what ways? |
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Definition
| product or substrate concentrations driving reactions or allosteric regulation of enzymes |
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Term
| What are the three general ways that intercellular communication occur? |
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Definition
Synaptic signalling via neurotransmitters
Endocrine signalling from hormone producing cells
Direct contact between cells (space between cells called gap junction) |
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Term
| What is a secondary messenger? |
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Definition
| molecules in cell that respond after messsenger (hormone etc) binds, helping to cause the ultimate cellular effect |
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Term
| What are the two most widely recognized secondary messengar systems? |
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Definition
adenyly cyclase system
calcium/phosphatidylinositol system |
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Term
| What are the only cells of the body that do not have carbohydrates as a primary fuel source? |
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Definition
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Term
| Hexokinase IV is predominantly found in which cells? |
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Definition
| Liver and Beta cells of the pancreas |
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Term
| How is Glucokinase regulated in the liver? |
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Definition
Sequestered and inactivated in the nucleus via Glucokinase regulatory protein (GKRP).
When glucose levels rise at to or above 10mM Glucokinase is released into the cytosol
Increased concentrations of fructose 6-phosphate will increase action of GKRP |
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Term
| How is Hexokinase I-III regulated? |
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Definition
| High concentrations of the product it produces (Glucose 6-phosphate) will inhibit action of Hexokinase |
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Term
| What allosterically inhibits Phosphofructokinase-1? |
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Definition
| ATP and Citrate (citrate is a product of the Krebs cycle) |
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Term
| What allosterically promotes Phosphofructokinase-1 (PFK1)? |
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Definition
| ADP, AMP, and Fructose 2,6-bisphosphate |
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Term
| How is fructose 2,6 bisphosphate created in the liver? |
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Definition
Activation of Phosphofructokinase-2 in the liver.
This enzyme is active when Glucagon levels are low. Glucagon activates the Adenylyl cyclase cycle which activates the secondary messenger cAMP which activates protein kinase A (PKA) which phosphorylates (read: deactivates) Phosphofructokinase-2 (PFK-2) |
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Term
| What enzyme intermediate upregulates the function of Pyruvate Kinase? |
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Definition
| Fructose 1,6-bisphosphate |
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Term
| How is pyruvate kinase inhibited? |
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Definition
Phosphorylation via PKA.
Remember PKA is activated through high levels of the hormone Glucagon. Which creates the cascade of adylyl cyclase -> cAMP -> PKA |
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Term
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Definition
| The cycle by which the product of anaerobic glycolysis (lactate) is recycled in the liver (gluconeogenesis) and then returned as glucose to the anaerobic tissue |
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Term
| What is the effect on Gluconeogenesis by Acetyl Coa? |
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Definition
| High levels with deactivate pyruvate dehydrogenase and activate Pyruvate Carboxylase |
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Term
| How is Fructose Biphosphatase 1 (FBPase-1) inhibited? |
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Definition
| By AMP and Fructose 2,6 Bisphosphate |
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Term
| How do hormones regulate genetic expression of key enzymes in Glycolysis? |
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Definition
| Increase in insulin or glucagon for a prolonged period of time regulates the transcription of Glucokinase, PFK-1, and Pyruvate Kinase |
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