Lipids Flashcards
How are FFA activated
Thioester binding
Why are fats a higher source of energy?
More H+
Glucose is already partially oxidised
What cells are involved which converts cholesterol into bile salts?
What releases bile salts?
Hepatic cells
Gall bladder
What do bile salts do?
Solubilise ingested fats
Allows pancreatic lipases to work
What hormone stimulates the secretion if FA?
Glucagon
What Lipase is involved with mobilisation of Triaglycerols out of lipid droplet
Hormone sensitive lipase
What stimulates the Hormone Sensitive Lipase?
What stimulates that?
PKA
Glucagon —> cAMP increase
What do VLDL transport?
What apoprotein is on it?
Endogenous lipids to body tissue
1x apoB-100
What does Chylomicron carry?
What apoproteins are on it?
Exogenous via lymph
B-48 /C3 /C2
What is the role of apoC-3
Inhibits lipase activity
Apo-C2
Activation of lipase
Apo-E
Liver recognition for degradation
What hormone stimulates LPL to go to the surface of capillaries?
Insulin
What does Insulin inhibit?
Lipases (ATGL/HSL/MGL)
Involved with triglyceride to FA
Why does insulin inhibit lipases?
Prevents FFA that came in to be ejected straight out
Prevents lipolysis
Promotes fat storage not mobilisation
What can stimulate lipolysis (2)
Glucagon
Catecholamines (ANP) fasting state
What part of Chylomicron is hydrophobic? Why?
Centre
Cholesterol and FA = Phobic
What does CM contain on its surface?
apoB-48
Familial hypercholesterolaemia
Mutation in LDL receptor
No uptake of FA
Plaque formation as LDL oxidised
HDL originates where?
Liver /intestine
What’s a role of HDL
Collect cholesterol from LDL /foam cells
What does a scavenger receptor do?
Collects cholesterol from HDL
What are the main roles of cholesterol
Membrane structure
Steroid hormones
Vit.D
Bile acids
What converts in CYTOPLASM
Acetate —> mevalonate
What happens if this occurs in mitochondria?
HMG -CoA reductase
Ketone bodies form instead
What provides all the carbons for cholesterol?
Acetyl CoA
What activates the synthesis of reductase?
What does it bind to?
SREBP
Promoter region
What is the cholesterol Sensor
What happens when Cholesterol is low?
INSIG
Cleaves SREBP
What hormone inactivated HMG-Reductase
Glucagon
What hormone stimulates cholesterol synthesis and HMG-Reductase
Insulin
What is the purpose of the carboxylation of Acetyl CoA
Synthesize longer fatty acid chain
Where does the carboxylation of Acetyl CoA occur?
Cytoplasm
How is the Acetyl CoA transported to the cytoplasm?
Acetyl + Oxaloacetate
=Citrate
Citrate transporter out of mitochondria
Citrate Lyase reconverts it back to Acetyl-CoA
Whats the first step of Carboxylation of Acetyl CoA
Malonyl Group + Acetyl-CoA
Condensation Reaction
C
Whats the 2nd stage of Carboxylation?
Reduction reaction
NADPH adds electron
R
Whats the 3rd stage of Carboxylation of Acetyl CoA
Dehydration (Dehydrogenase)
D
Whats the 4th stage of Carboxylation of Acetyl CoA
Reduction reaction
NADPH adds electron
R
Whats the acronym for remember the carboxylation of Acetyl CoA
C
R
D
R
What enzyme is used in Carboxylation of Acetyl CoA
Fatty acid synthase
Addition of other CoA to form 16C occurs how many times
7x
16C
Palmitate
Where are electron donors come from?
Phosphate pentode pathway
Where are the ATP from?
Oxidative phosphorylation
Where are the ACoA from?
Krebs
How many are used in Palmitate synthesis?
ATP?
ACoA
NADPH
7ATP
8ACoA
14NADPH
What hormones can Palmitate form?
Eicosanoid hormones
Where does Palmitate form longer FA
Why?
SER / Mitochondria
Mixed function Oxidase is located
What are the 4 main sources of Triacyclglycerol?
Pyruvate
Glucose
FA
Glycerol
L-Gylcerol 3-P = Diacyglycerol 3-P
Acetyl transferase
2xACoA
2ATP
Diacylglycerol 3-P can form two things?
Glycerophospholipid (membrane)
Diacyglycerol
Diacyglycerol 3-P to form
Diacyglycerol is what type of reaction
Hydrolysis
Diacyglycerol to form
Triacylglycerol is what type of reaction
Transestification
How is activated Acyl-CoA moved into Mitochondria
Carinitine Shuttle
How is the Carinitine Shuttle regulated by?
Manoyl CoA
Which enzyme adds Carnitine and Activated Acetyl CoA together?
Carnitine Acyltransferase 1
Whats the acronym for B-Oxidation
O
H
O
T
What type of enzymes do Oxidation reactions
Dehydrogenase
What does the first step of B-oxidation produce?
FADH2
1.5ATP
What does the third step of B-Oxidation produce?
NADH
2.5ATP
What does the last stage of B-Oxidation produce
Acetyl-CoA (For Krebs)
2 Less carbon Fatty acid
How many ATP are produced without the use of Acetyl CoA in Palmitic Acid?
Why?
28ATP
Cycle occurs 7x
4ATP / cycle
How many ATP are made from Acetyl CoA from Palmitic Acid?
Why?
80ATP
1ACoA = 10ATP
Cycle 8x = 80ATP
What is the net ATP from Palmitic Acid?
106ATP
108ATP made
2ATP for Acyl-CoA synthase
How much ATP is made from Glycerol?
18.5
8.5. 10 Glycerol ——-> ACoA ——> citric Acid
Name an Unsaturated Fat
Oleate
What is need for Boxidation of a unsaturated fat?
Isomerase
Reductase
What does the isomerase do?
Change bond from Cis to trans
Allows hydratase to work
Name a polyunsaturated fat
Linoleate
What does reductase do?
Adds electron to double bond
Converts Trans-Cis —> Trans
Why do polyunsaturated fats produce 1.4% less energy
Skips first stage of B-Oxidation
No FADH2 made
High glucose levels means what for B-Oxidation
Why?
No B-Oxidation
As Malonyl CoA is high
MCoA regulates C.Acyltransferase 1
Name 3 ketone bodies
Acetoacetate
D-B- hydroxybutyrate
Acetone
What do ketone bodies allow?
Continuous oxidation of FA
When are ketone bodies used?
Oxaloacetate is in short supply due to starvation
What can ketone bodies lead to
Acidosis/ketosis
What can acetone be used for (ketone body)
Lungs
