Flashcards
BMS07-1027-Fat Storage and Transport
Cards in this deck (34)
- 1What are the three steps of fatty acid synthesis?1. Acetyl CoA from the cytosol is transported into the mitchondria membrane
2. Malonyl CoA synthesis from acetyl CoA
3. Fatty acid chain Synthesis - 2How is acetyl CoA transported into the mitochondrial membrane?It combines with oxoloacetate to form citrate, which enters the membrane
It then breaks down into Acetyl CoA+oxoloacetate again - 3How is acetyl CoA converted to Malonyl CoA? What enzyme catalyses this? What is this rxn stimulated by?1. Acetyl CoA+HCO3- --> Malonyl CoA
(ATP-->ADP+Pi)
2. Acetyl CoA carboxylase
3. Stimulated by insulin - 4What is the rate limiting step of Fatty Acid Synthesis?The conversion of acetyl CoA to malonyl CoA
- 5What are the two purposes of Malonyl CoA?1. Precursor to fatty acid chain
2. Inhibits cartinine transferase, which is important for fatty acid oxidaton (so lowered oxi. of fats) - 6How is malonyl CoA converted to a fatty acid chain? What type of reaction is this? What enzyme is required?1. Malonyl CoA+Acetyl CoA-->Fatty acid chain
2. Reduction reaction (requires NADPH)
3. Fatty Acid Synthase - 7Triacylglycerol (TAGs) are made of what?A glycerol (G3P) + 3 fatty acids
- 8What are the four sources of G3P for TAG synthesis?1. Glycerol from glycerol kinase
2. Oxoloacete-->DHAP-->G3P via TCA cycle
3. Amino acids (fumarate/pyruvate) via TCA
4. Reducing NADH via G3P Dehydrogenase - 9Where in a lipoprotein are TAGs, cholesterol and esters located?Inner layer of lipoprotein
- 10Where in a lipoprotein are apoproteins and cholesterol located? What else is in the layer?Out layer
Phospholipid Bilayer - 11Which of the TAGs are the largest, have the lowest density, and mainly come from dietary sources?Chylomicrons
- 12Where are chylomicrons formed? What are packaged together to form one?In the SER of epithelial cells in the small intestine
- TAGs, cholesterol, cholesterol esters, B48 - 13What is the role of Apoprotein B48?Transports Chylomicron to lymphatic system
- 14What does a chylomicron pick up in the circulation?ApoE
ApoC2
Both picked up from HDL - 15When a chylomicron breaks down in the capillaries, what are the three components and where do they go?1. ApoC2 returns to HDL
2. B48/ApoE is reuptaken by ApoE receptors on liver
3. TAG is broken down by lipoprotein lipase into glycerol+fatty acid - 16What happens to glycerol after it is seperated from TAGs?Goes to liver for gluconeogenesis
- 17What happens to the fatty acids from TAGs?Fatty acids enter adipocytes (tissue) for esterification into TAGs
- 18What activates the lipolysis of TAGs? What enzyme is used?1. Insulin/ApoC2
2. lipoprotein lipase - 19Which lipoprotein mainly carries endogenous TAG from the liver?VLDL
- 20Where is VLDL from and what are packaged together to form it?From liver to tissue
TAGs, cholesterol, cholesterol esters and B100 packaged together - 21What does VLDL pick up in the systemic circulation?ApoC2
ApoE
Both from HDL - 22What does VLDL break down to in the capillaries?1. TAGs
2. Intermediate Density Lipoprotein (IDL) - 23What happens to IDL?Doesn't live very long
Returns ApoE/ApoC2 to HDL - 24What is LDL made of and what happens to it?1. Made of TAGs+B100
2. 50% goes to liver, 50% goes to peripheral tissue via B100 receptor - 25How does LDL deliver cholesterol to peripheral tissues via the B100 receptor?1. Enters via endocytosis
2. Lysosome breaks down LDL, leaving cholesterol
3. Cholesterol enters nucleus - 26What does cholesterol normally do in the nuclues? What can obstruct this process?1. It inhibits the synthesis of enzymes that produce cholesterol, thus lowering cholesterol production
2. A deficiency in B100 receptors can lead to high LDL levels/arteriosclerosis - 27Which Chylomicron is a shuttle for apoproteins and delivers cholesterol from tissue to liver?HDL
- 28What converts Nascent HDL to HDL? What is required for this reaction?LCAT
ApoA1 - 29How does HDL transport cholesterol from tissue to liver?1. HDL uptakes cholesterol from peripheral tissue
2. Cholesterol combines with fatty acids to become cholesterol esters
3. Delivered to liver for elimination - 30What are 3 genetic causes for elevated lipid levels (hypercholesterolaemia/hypertriglyceridaemia)?1. Defective LDL (B100) receptor increases LDL in blood
2. Lipoprotein lipase deficiency increases chylomicrons/VLDL in blood
3. ApoC2 deficiency so lipoprotein lipase cannot be activated - 31What are three secondary causes of elevated lipid levels?1. Obesity
2. Diabetes II
3. Dietary fatty acid - 32What is lipoprotein A? What does it do? It's levels are increased by what?1. It is LDL+ApoA
2. Slows breakdown of blood clots by competing with plasminogen/fibrin, increases CHD risk
3. Increased by transfat/cholesterol - 33To prevent the synthesis of cholesterol, which enzyme must be inhibited? What inhibits it?1. HMG-CoA reductase, because it catalyses the rate limiting step in the conversion of acetyl CoA to cholesterol
2. STATINS can inhibit it - 34What do the following do? ApoB48 ApoC2 ApoE ApoB100 ApoA11. Apo48 Transports chylomicrons into the lymphatic system
2. ApoC2 Initiates the hydrolysis of TAGs for absorption
3. ApoE Enables reuptake of remenants
4. ApoB100 binds to LDL receptors allowing for uptake in tissue
5. ApoA1 activates LCAT to convert nascent HDL to HDL
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- Description
- outline the process of lipid synthesis in liver and the main control points Identify the major lipid carried by each of the main lipoprotein classes: chylomicrons, very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL). origin and fates of each of these lipoprotein classes. main causes and consequences of the most common hyperlipoproteinaemias Indicate the importance of HMGCoA reductase inhibitors in treating high cholesterol
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- Evian Chai
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