Nutrition And Metabolism Flashcards
What molecule carries indgested fat through the digestive system
Chylomicrons
What happens to excess dietary carbs?
Undergo insulin stimulated lipogenesis (glucose goes to fatty acids then to TG)
What aretriglycerides packaged in before being secreted from the liver?
VLDL (Very Low Density Lipoproteins)
What enzyme digets the TGs from chylomicrons and VLDLs to release fatty acids?
Lipoprotein Lipase
What happens to excess mitochondrial citrate in lipogenesis?
Exported by citrate shuttle to cytosol for fatty scid synthesis and Acetyl CoA
What is the rate limiting factor in fatty acid synthesis?
The carboxylation of acetyl CoA to malonyl CoA by Acetyl CoA carboxylase
What does FAS enzyme do?
Condenses malonyl CoA to Acetyl-CoA to create nascent fatty acids
What does Maonyl CoA inhibit?
The movement of fatty acids through the mitochondria
Name 5 lipoproteins
Chylomicrons, VLDLs, IDLs, LDLs, HDLs
Where and how are VLDLs made?
Made in the hepatocytes from TG, cholesterol and apolipoprotein B100
What is reverse cholesterol transport?
HDLs take up excess cellular cholesterol from peripheral tissues to return it to the liver
What does the Pentose Phosphate Pathway produce and from what?
Generates NADPH from NADP+
What happens in the Oxidative stage of PPP
Glucose-6-Phosphate goes to 6-Phosphogluconate using Glucose-6-Phosphate Dehydrogenase. 6-Phosphogluconate then goes to Ribulode-5-Phosphate using 6-Phosphogluconate Dehydrogenase
What is the interconversion stage of PPP and what happens to the products?
Ribulose-5-Phosphate goes to Glyceraldehyde-3-Phosphate and Fructose-6-Phosphate, these are shunted back into Glycolysis
What is Steatorrhea
When undigested fats are found in stool samples
What state do you enter when fasting?
The Basal State
What does Insulin do to HSL
Insulin inactivated Hormone Sensitive Lipase
What happens in metabolic respiration?
Glucose, fatty acids and amino acids are oxidised into acetyl CoA, which then enters the TCA cycle
How do long chain fatty acids cross membranes?
Carnitine cycle
What mist happen to all fatty acids before oxidation?
Activation, this involves forming a thioester linkage to coenzyme A to for, fatty acyl CoA
Describe the Carnitine Shuttle
As CoA cannot peneratrate the inner mitochondiral membrane CPT 1 swaps CoA bound to the fatty acyl to carnitine, the Carnitine-acyl carnitine translocase transports the new fatty acyl carnitine over the mitochondrial membrane, CPT 2 then swaps the carnitine back to CoA. Free carnitine is then pumped back into the inter membrane space
What is the fed state
When after eating we use fuel to make energy AND stores for later
What is the starved state?
In the absense of food the body will deplete available energy stores and becoem reliant on producing its own glucose
What is the process of oxidising fuels to CO2 and H2O to produce ATP
Catabolism
Describe the insulin signalling cascade
Insulin binds to glucose activating
Tyrosine kinase activation and autophosphorylation. This will catalyse phosphorylation of cellular proteins resulting in the translocation of GLUT 4 transporters to plasma membranes. This will result in the uptake and storage of glucose
Where is GLUT 1 found?
Blood brain barrier
Where is GLUT 3 found?
Found in neurones
Where is GLUT 4 found?
Skeletal muscle and adipose
What is special about GLUT 2 and where is it found?
Its bi-directional and is found at the liver and kidneys
