Bioenergetics Flashcards
What happens in PDC deficiency and what is recommended to help reduce the effects of it?
Pyruvate is not decarboxylated and so Glucose is converted to Lactate instead of Acetyl CoA. This causes lactic acidosis.
A ketogenic diet may be recommended, as well as restricting Alanine intake, because Alanine is converted to pyruvate
Succinate dehydrogenase is related to Oxidative phosphorylation in what way
It is also known as Complex II in oxidative phosphorylation. It generates FADH2 which enters the chain at Coenzyme Q
What are the two major anaplerotic reactions for TCA cycle
Degradation of amino acids
Carboxylation of pyruvate
Does complex V pump protons?
No, it uses the already established proton gradient to create ATP
Malate aspartate shuttle operates where and generates what
In heart, liver and kidneys
Generates NADH
Glycerophosphate shuttle operates where and generates what
Skeletal muscle and brain
Generates FADH2
What is the relationship between creatine kinase (CK-MB) and Myocardial infarctions
CK-MB can be used to help diagnose an MI, because there will be abnormally high levels of it in the serum starting 4-8 hours after an MI and peaking at 12-24 hours (due to damage to the heart). Skeletal muscle damage can also cause high levels of CK-MB so other markers such as troponin T may be used as well.
What is the rate limiting enzyme in TCA cycle
Isocitrate dehydrogenase
What is acetyl CoAs role in other metabolic pathways
It can be used as a building block for lipid synthesis (FAs) or isoprenoids. During fasting or in diabetes, much Acetyl CoA is formed from breakdown of fatty acids. However, it cannot be used in the TCA cycle because oxaloacetate is being used in gluconeogenesis
Therefore, it ends up being converted to ketone bodies
Energy from glucose versus fatty acids
Fatty acids give off much more energy (9kcal/g vs 4kcal/g)
What is the effect of calcium and magnesium on PDC
Calcium and magnesium both activate PDC by directly binding and activating PDP (cardiac and skeletal muscle). In adipose tissue, insulin may activate PDC
Arsenic and PDC
Arsenite modifies a subunit of PDC and disrupts its function
Beriberi and Wernicke-korskoff syndrome
Caused by deficiency in thiamine, which is an essential cofactor for PDC and a-ketoglutarate dehydrogenase. There will be increased serum levels of pyruvate and a-ketoglutarate. Wernicke-korskoff is caused in alcoholics because ethanol reduces thiamine uptake.
Pyruvate dehydrogenase deficiency (neonatal lactic acidosis)
Due to defects in E1 subunit of PDC. There will be elevated levels of lactic acid and pyruvate in the serum, all though the ratio will be normal. Ketogenic diet may be recommended
Citrates effects on rate limiting enzymes, and what does high citrate indicate
High citrate indicates high levels of ATP. It is an inhibitor of PFK1 in glycolysis. It activates fatty acid biosynthesis via activation of acetyl CoA carboxylase
