Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
49 Cards in this Set
- Front
- Back
|
What is it called when lipids are deposited in the arterial wall? |
athersclerosis |
|
|
What soluble protein transports unesterified fatty acids? |
albumin |
|
|
List the major component of Chylomicron |
Tryglicerides (83%) (and Cholesterol (8%)) |
|
|
List the 2 major components of very low density lipoprotein (VLDL) |
Cholesterol (22%) and Tryglicerides (50%) |
|
|
List the 2 major components of low density lipoprotein |
Cholesterol (50%) and Phospholipids (22%) |
|
|
List the 3 major components of high density lipoprotein |
Protein (50%) and cholesterol (20%) and phospholipids (22%) |
|
|
What do chylomicrons transport? From where to where? |
They transport triglycerides from the diet (intestines) to adipose (fat storage) |
|
|
What does VLDL transport? From where to where?
|
Triglycerides from liver to adipose (fat storage) |
|
|
What does LDL transport? From where to where? |
Cholesterol from the liver to periphery |
|
|
What does HDL transport? From where to where? |
Cholesterol from periphery to liver |
|
|
What organ excretes cholesterol? |
The liver |
|
|
What happens when LDL levels are too high? |
LDL deposits cholesterol into the arterial wall (bad cholesterol) |
|
|
What are triacylglycerols made of? |
Fatty acids attached to a glycerol backbone |
|
|
What are fatty acids broken down into? |
Acetyl-CoA (feeds to citric acid cycle) |
|
|
Why is triacylglycerol synthesis called an overflow pathway? |
Because all nutrients can be converted to acetyl-CoA, and thus to fatty acids and then triacylglycerol. There is no feedback inhibition of TG synthesis, so excess nutrients can be stored as TG |
|
|
What are the two substrates of triacylglycerol synthesis? |
Glycerol-3-phosphate and fatty acyl CoA |
|
|
What are the 3 sources for glycerol-3-phosphate |
1. Glycerol kinase (liver) - phosphorylates glycerol to glycerol-3-phosphate 2. Glycolosis (adipose tissue) - from dietary glucose 3. Glyceroneogenesis (adipose tissue) - like gluconeogensis but stops at g3p |
|
|
True or false. Glycolysis and glyceroneogenesis can be active at the same time. |
False. |
|
|
Where is DHAP derived from when glucose is available? When glucose is not available? |
Available = glycolysis Not available = glyceroneogensis |
|
|
How does DHA get changed into glycerol-3-phosphate? |
Reduction (NADH2 -> NAD+) |
|
|
How and where is TG hydrolyzed? |
TG is hydrolyzed in capillaries outside the cell by lipoprotein lipase |
|
|
What is an adipocyte? |
A fat cell |
|
|
How is TG made from fatty acids? |
1. Fatty acids are activated with CoA to create fatty-acyl-CoA 2. Fatty-acyl-CoA are esterified with glycerol-3-phosphate to make triacylglycerols (TG - energy storage as fat) |
|
|
Why is TG hydrolyzed? |
TG is hydrolyzed when the body requires energy. Fatty acids and glycerol are secreted into the bloodstream. |
|
|
What is lypolysis? |
The breakdown of lipids including hydrlysis of TG into fatty acids and glycerol |
|
|
What regulated lypolysis? |
Adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL) - both are more active when energy stores are hydrolyzed |
|
|
Where does glycerol go once it is released into the bloodstream? |
It goes back to the liver. Adipose tissue doesnt have glycerol kinase, so it is prevented from reusing the glycerol |
|
|
What happens to glycerol in the liver? |
The liver uses glycerol in gluconeogenesis or glycolysis depending on its need |
|
|
What happens to the fatty acids? What are they broken down into? |
1. ATP and CoA are used to turn fatty acids into fatty acyl-CoA (in the cytosol) 2. NAD+ and Q are hydrolyzed to NADH and QH2 (in the mitochondria - used in electron transport chain) as fatty acyl-CoA is turned into acetyl Co-A (which is then oxidized in the citric acid cycle) |
|
|
Fatty acid oxidation - how are fatty acids are broken down |
1. Broken down in the matrix 2. Each reaction cycle removes 2 carbons from the carboxyl end of the chain (also called beta-oxidation) 3. Each reaction cycle produces 1 NADH and 1QH2 4. Product: Acetyl-CoA 5. Requires oxygen |
|
|
What regulates fatty acid oxidation? |
The transport step of fatty acids into the mitochondria |
|
|
How are fatty acids activated? |
Activated in the cytosol through conjugation to Coenzyme A (CoASH). ATP is hydrolyzed to AMP and ppi. Reaction is driven by hydrolysis of ppi |
|
|
How are fatty acyl groups imported into the mitochondria? |
Via a carnitine transporter |
|
|
How does a canitine transporter work? |
1. Acyl-CoA reacts with carnitine to produce acyl-carnatine. 2. Acyl carnitine is transported through the carnatine transporter into the matrix 3. Acyl-carnatine reacts with HSCoA and produces Acyl-CoA (now in matrix) and carnatine that then reenters the cytosol again |
|
|
What happens when there is a carnatine deficiency? |
It slows down and prevents fatty acid oxidation |
|
|
Steps of Beta-Oxidation First oxidation |
Fatty acyl-CoA --> enoyl-CoA Electrons are transferred and FAD forms FADH2, electrons are then transferred from FADH2 to Q to form QH2 Catalyzed by a dehydrogenase |
|
|
Steps of Beta-Oxidation Hydration |
Enoyl-CoA --> 3-hydroxyacyl-CoA Catalyzed by addition of H2O |
|
|
Steps of Beta-Oxidation Second Oxidation |
3-hydroxyacyl-CoA --> ketoacyl-CoA Electrons are transferred to NAD+ forming NADH Catalyzed by a dehydrogenase |
|
|
Steps of Beta-Oxidation Cleavage, thiolysis |
Ketoacyl-CoA --> Fatty acyl-CoA (2 C atoms shorter) + Acetyl-CoA Catalyzed by thiolase and CoASH Shortened acyl-CoA chain undergoes next round of oxidation |
|
|
How much energy is yielded from the oxidation of stearic acid? (C18:0) |
8 rounds of oxidation = 8 NADH, 8 QH2, 9 acetyl-CoA 9 acetyl-CoA into TCA cycle = 9GTP, 27 NADH, 9 QH2 Total: 35 NADH and 17 QH2 and 139 ATP |
|
|
Oxidation of very long chain fatty acids |
Oxidation in peroxisomes to medium chain fatty acids which are then oxidized in the mitochondria Peroxisomal fatty acid oxidation does not yield ATP |
|
|
Oxidation of unsaturated fatty acids |
Need additional enzymes to degrade carbon chain around double bonds odd number db need isomerase even number db need dehydrogenase Lower energy yield than from saturated fatty acids |
|
|
Oxidation of odd chain fatty acids |
Oxidation yields propionic acid which is converted to succinyl CoA. This is the only way that part of a fatty acid can be glucogenic |
|
|
Define glucogenic |
Can be converted to glucose through gluconeogenesis (unlike keotgenic that can only be converted to ketone bodies) |
|
|
Oxidation of branched-chain fatty acids |
Branch points in chain prevent beta-oxidation. Can only be broken down by alpha-oxidation Occur in dairy products and products derived from herbivores |
|
|
What happens after the last cycle of beta-oxidation? |
You are left with CH3-CH2-(C=O)-SCoA (propionyl-CoA - odd chain fatty acid) Propionyl-CoA --> Succinyl-CoA ATP, CO2, and vitamin B12 are required and leaves behind ADP + pi Vitamin B12 deficiency causes neurological damage because of accumulation of odd chain fatty acids |
|
|
3 stages of fatty acid synthesis |
1. Transfer of acetyl-CoA into cytosol from mitochondria (fatty acid synthesis only happens in mitochondria) 2. Activation of acetyl-CoA to malonyl CoA 3. Intermediates attach to a carrier protein and the chain is synthesized two carbons at a time in a 5 step elongation cycle |
|
|
What is the rate limiting step in the conversion of acetyl-CoA --> malonyl CoA? |
Acetyl-CoA carboxylase catalyzes the first step in fatty acid synthesis This is an irreversible reaction |
|
|
What catalyzes fatty acid synthesis? |
Fatty acid synthase - an enzyme that has all activities necessary for the reaction steps |
