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9 Cards in this Set
- Front
- Back
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What three metabolic cycles occur in both the mitochondria and the cytoplasm?
Which cylces occur exclusively in the mitochondria? |
Heme synthesis, Urea Cycle, Gluconeogenesis
Mito only: Fatty acid oxidation (B ox), acetyl CoA production, TCA, ox phos Cyto only: Glycolysis, FA synthesis, HMP shunt, steroid and protein synthesis (SER and RER) |
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How does a kinase differ from a phosphorylase?
What vitamin is used to assist a carboxylase enzyme? |
Kinase = phosphorylates using ATP
Phosphorylase= phospphorylates without using ATP Carboxylase --> uses the help of biotin |
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What metabolic pathways are active in the Fed state and Fasting state?
What hormone level is elevated during each? |
Fed state- glycolysis, aerobic respiration (Insulin is ↑)
Fasted state- glycogenolysis (major), gluconeogenesis and adipose release of FFA (minor) (Glucagon ↑) |
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What is the Rate determining enzyme of Glycolysis?
At what step of the pathway do we use Hexokinase/Glucokinase? What is the difference between the two? |
Phosphofructokinase (PFK-1)
Glucose --> Glucose-6-P (use hexo/gluco) Hexo is ubiquitous, high binding affinity (low Km), low Vmax (low capacity) and not induced by insulin. Inhibited by glucose-6-P Glucokinase is in liver and pancreatic cells. Low affinity (high Km), high Vmax, induced by insulin. Binds excess glucose & sequesters it in liver. |
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How is blood glucose level maintained during 1-3 days of starvation?
After 3 days? |
1st- Glycogenolysis --glycogen reserve is depleted after a day
2- Fatty acid oxidation-- adipose tissue releases FFA (muscle and liver start to use FFA) 3rd- Hepatic gluconeogenesis-- from lactate, alanine, glycerol, etc. After 3 days, body rapidly depletes important proteins and organ failure and death result |
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Rate limiting step of cholesterol synthesis?
What is the function of LCAT? |
HMG CoA reductase (inhibited by statins)
Lecithin cholesterol acetyl transferase is an enzyme that esterifies cholesterol (i.e. adds an OH or free fatty acid to make it into storage form) |
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What is the function of Hepatic TG lipase?
What about CETP? |
Hepatic TG lipase- like LPL but works on IDL (to degrade the TGs that are remaining in it)
CETP = cholesterol ester transfer protein (transfers CE from HDL in exchange for TGs to VLDL, IDL, and LDL) |
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On what particle would we find the following lipoproteins:
AI CII B-48 B100 E |
AI (binds LCAT) - nascent HDL and CM
CII (binds LPL)- CM, VLDL, HDL B-48 (helps secrete CM) - CM, CMR B-100 (binds LDLR)- VLDL, IDL, LDL E (mediates uptake into liver)- All except LDL |
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What is Abetalipoproteinemia?
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Disorder in MTTP (microsomal TG transport protein). It packages the TG and CE into chylomicrons and releases them from enterocytes.
If defective, it can cause failure to thrive, steatorrhea, acanthocytosis, ataxia, nigh blindness (from ↓ levels of fat-soluble vitamins). Also renders enterocytes incapable of exporting lipoproteins and FFA. |
