Lipids Flashcards
What are some properties of lipids
Heterogenous
Insoluble in water
Exist in cell membranes
What are the different lipid classes
F.A
Triacylglycerol
Phospholipid
Glycolipid
Steroids
What are the essential FA and where do we get them from?
Linoleic
Linolenic
We get from plants
What are triacylglycerols
Esters of FAs and glycerol
TAG major lipid in adipose tissue
Used for fuel and insulation
What are the properties of phospholipids
Amphipathic:
Glycerol + 2FA+ phosphate group
Contain a Hydrophilic head and hydrophobic tail
What are the Main Steroids
Cholesterol
Steroid hormones
Bile salts
Properties of cholesterol
-Precursor to Sterol hormones and bile salts
-Made in liver
-Found in animal food
How is cholesterol synthesis regulated
Via statins
Inhibit HMG-CoA reductase
What are eicosanoids and what do they regulate?
Lipid class derived from 20C unsaturated FA
Regulate:
inflam response
B.p
clotting
Pain & fever
What is the main dietary lipid
Triacylglycerol
What is the main site of lipid digestion
small intestine
What are lipids digested by
Lipases via emulsification by bile salts and mixing
What are bile salts
Biological detergents
Derivative of cholesterol
How is TAG digested
In small intestine via pancreatic lipase->monoacylgycerol + 2FA
What is cholesterol esters digested to
Cholesterol and free FA
How are phospolipids digested
Hydrolysed to FA and lysophospholipid
How are digested lipids uptaken
Form mixed miscelles with bile salts
Enter cells via diffusion
How are absorbed FA transported
Packaged into chylomicrons
Released by exocytosis into lymph then blood
Summary of lipid digestion
Bile salts emulsify dietary fats in the small intestine
Intestinal lipases degrade triglycerol
Fatty acids and other breakdown products are absorbed by the intestinal mucosa and converted to triaglyceroids.
Triaglycerols are incorporated with cholesterol
Lipoprotein lipase converts triaglycerols into fatty acids
Fatty acids enter cells
Fatty acids are oxidized as fuel
How are FA transported in blood
Serum albumin
Esterified FA carried in lipoproteins
What do lipoproteins carry
TAG, cholesterol
What are the lipoprotein classes
Chylomicrons
VLDL
LDL
HDL
What are the fates of FA after metabolism in plasma
Oxidation - energy
TAG formation
FA->Fatty acetyl CoA->Triglyceride
What does B-oxidation of FAs involve
Degrades FA 2 carbons at a time
Produces acetyl CoA +NADH + FADH2
Occurs in mitochondrial matrix
What happens on B-oxidation
- Activation of FA in cytosol
- Transport into mitochondria
- Degredation to 2C in mitchondrial matrix
What does transport of FA involve
Carnitine shuttle
What are the 4 degredation steps of B-oxidation
- Dehyrdrogenation FAD->FADH2
- Hydration
- Dehydrogenation NAD+->NADH
- Thiolysis- produces acetyl CoA for CAC
What happens during starvation
Excess acetyl CoA from fat metabolism converted to ketone bodies
What are ketone bodies used for
Cardiac and skeletal muscles use it as energy source
Fuels brain cells during starvation
Where does FA synthesis occur
Liver
Mammary gland
Adipose tissue
FA synthesis and degredation
