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14 Cards in this Set
- Front
- Back
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Why can't the NADH produced in step 6 of glycolysis participate directly in the ETC?
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Because NADH (and NAD+) are impermeable to the mitochondrial membrane
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What are the two systems for transferring electrons of NADH into mitochondria?
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(1) They glycerol phosphate shuttle
(2) the malate-aspartate shuttle |
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What occurs in the glycerol phosphate shuttle?
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- Dihydroxyacetone phosphate (DHAP) is reduced by NADH to produce glycerol-3-phosphate, which is permeable to the outer mitochondrial membrane
- At the outer membrane the electrons are transferred to FAD to produce FADH2 and then directly to the ETC |
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What occurs in the malate-aspartate shuttle?
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Transfers electrons from cytoplasmic NADH to mitochondrial NAD to form mitochondrial NADH, which is then oxidised by the ETC
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How many molecules of ATP are produced in one complete oxidation of glucose from oxidative phosphorylation?
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26 ATP
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What does ethanol do to the ratio of NADH/NAD+?
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Moderate alcohol consumption, the level of NADH is increased
* Large quantities of EtOH increase the rate of NAD+ reduction and the rate of shuttle transfer of NADH may not keep up |
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In the presence of alcohol-induced high NADH levels in the liver, pyruvate availability is diminished, which means gluconeogenesis is diminished and an adequate amount of glucose is not going to the brain. True or False?
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True
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When pyruvate availability is diminished, what leaks into the blood and what does it cause?
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Lactate leaks into the blood causing lactic acidosis.
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What is Diabetes mellitus?
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A chronic condition due to either insufficient insulin or failure of insulin to activate crossing of cell membranes, by glucose.
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What is T2DM classified as?
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It is thought to result when cell membrane receptors fail to recognise insulin, called insulin resistance. It is frequently associated with obesity.
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What is T1DM classified as?
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Type 1 diabetwe is classified as an autoimmune disease, where the immune system wrongly identifies pancreatic beta cells as foreign matter, develops antibodies to them, and destroys them. This results in deficient insulin production.
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What are the effects of insulin?
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- signifies the presence of fuels in the body, or the fed state
- Increases glucose uptake into cells (muscle and adipose tissue) - Promotes glycogen synthesis - Increases fatty acid synthesis in the liver - Decreases synthesis of phosphoenolpyruvate carboxykinase (PEPCK), which catalyses the conversion of oxaloacetate to phosphoenolpyruvate (thereby inhibiting gluconeogenesis) |
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High glucagon/insulin rationpromotes gluconeogenesis by leading to what?
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- decrease in the amount of fructose 2,6-bisphosphate in the liver
- increases glycogen breakdown in the liver - activates lipolysis in adipose cells so the blood level of free fatty acids is high |
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When there is glucose in the blood, what is it converted to?
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Sorbitol
*Sorbitol is not transported out of the cell and rising concentrations increases the osmolarity of fluid in the eye - causes problems |
