Lipids Flashcards
What are lipids
Heterogenous molecules
Insoluble in water
Biological functions
Energy storage Structural Enzyme cofactors Hormones Vitamins A,D, E,K Signalling
Major lipid classes (5)
Fatty acids Triaglycerol Phospholipid Glycolipid Steroids
Fatty Acids
Unstaurated- double bond
Saturated- single bond
Essential- humans cannot introduce double bonds begone carbon 9
Triacylglycerol
Esters of Fatty acids and glycerol
Main dietary lipid
Most degraded in small intestine to monoacylglycerol and 2 FA
Phospholipids
Glycerol bound to 2 fatty acids and phosphate molecule
Bile salts
Biological detergents- emulsions and mixed micelles
Derivatives of cholesterol
Steatorrhea
Lipid malabsorption due to defects in bile secretion, pancreatic function or intestinal cell
Fat in faeces
Utilisation of Dietary Lipids
- Bile salts and dietary fats form mixed micelles
- Intestinal lipases degrade TAG
- Brush border of enterocytes and enter mucosa by diffusion
- TAG are packaged with apoB-48 into chylomicrons
- Chylomicrons travel through lymphatic system
- TAG are converted to FA and glycerol
- FA used as fuel or resterfied, glycerol»_space; G3P
Synthesis and Storage of TAG
TAG is stored in adipose tissue
How are FA released from TAG store
Hormone sensitive lipase is activated when phosphorylated in response to epinephrine when blood glucose and insulin is low
How are FA transported in the blood
Free FA is transported in a complex with serum albumin
Lipoproteins
Core full of fat and cholesterol along with apolipoporoteins
Classes of Lipoproteins
Chylomicrons
VLDL
LDL
HDL
B oxidation of fatty acids
Activation: fatty acyl CoA using ATP Transport to mitochondria: Carnitine (CAT-1) Degradation: Dehydrogenation = FADH2 Hydration = H2O Dehydrogenation = NADH Cleavage = Thiolysis = acetyl CoA
Synthesis of Fatty acids
Acyl group + malonyl group Elongation- condensation Reduction- NADPH Dehydration = H2O Reduction- NADPH FA cleavage
Steroids hormones
Chemical substances that serve as chemical messengers in the body
Testosterone, progesterone
Eicosanoids
Precursor from prostaglandins, thromboxane and leukotreines
Signalling molecules derived from Omega 3 and 6
Cholesterol
Precursor for: Bile Vitamin D Steroid hormones Membranes Plasma lipoproteins
Statins
Inhibit HMG-CoA reductase- essential in cholesterol synthesis
COX inhibitors
inhibition of COX enzyme
Prostaglandin synthesis
and thromboxane synthesis
Ketone bodies are formed in the____
Liver
B-oxidation occurs in the_____
Mitochondria
Fatty acid synthesis occurs in the _____
Cytosol
What organs and tissues does fatty acid synthesis occur in
Liver
Lactating mammary gland
Adipose tissue
Citrate shuffle is used to_____
Move acetyl CoA out of mitochondria
Acetyl CoA carboxylase
activation and regulation