Lipids 1 Flashcards
Where are the different places you can find lipids in the body?
Cell membranes, lipid droplets in adipose tissue, in blood lipoproteins
What are some of the biological functions of lipids?
Stored form of energy, structural element of membranes, enzyme cofactors, hormones, vitamins A,D,EK, signalling molecules
What are the different classes of lipids?
Fatty acids, triacylglycerol, phospholipids, glycolipid and steroids
When writing the structure of a fatty acid, what does the term 18:2(9,12) mean?
There are 18 carbons with two double bonds, occuring at carbon atoms 9 and 12
What are the essential fatty acids?
Linoleic and aplha - linolenic - must get these from plants
What are good fats?
High in polyunsaturated fatty acids e.g vegetable oil, sunflower oil and olive oil
What are the bad fats?
High in saturated fatty acids? e.g. stearic (beef)
What useful function do saturated fatty acids have?
Huge role in myelination of nerve fibres and hormone production
What are the really bad fats?
Trans fatty acids
How are these really bad fats made?
Hydrogenation of vegetable oils
Up to which point in a fatty acid chain can a human no longer produce a double bond?
9
What can be derived from linolenic acid?
Omega three fatty acids
What effect does omega 3 have?
lowers plasma cholesterol prevents atherosclerosis, lowers triacylglycerol
What is derived from linoleic acid?
Omega 6
What are the effects of fatty acid deficiency?
Growth retardation, reproductive failure, skin lesions, ADHD - more behavioural problems Depression
How would you describe the Ph and charge of an ester?
Neutral and uncharged
Describe the solubility of triacylglycerol
Insoluble in water
What is the main lipid component of adipose tissue?
Lipid droplets
What can triacylglycerol be used for?
Fuel and insulation
What is the main dietary lipid?
Triacylglycerol
What is the main site of lipid digestion?
Small intestine
Lipases are involved in lipid digestion, where are lipases made?
Pancreas
What effect does bile salts have?
Emulsification of lipids (breaks down fat globules into smaller droplets) - larger surface area for lipase to act onForms mixed micelles
What physical mechanism helps with protein digestion?
Peristalsis
What are bile salts derivatives of
Cholesterol
What are micelles?
The end product of fat digestion is converted into these - They are small water soluble droplets. They are closed lipid monolayers with a fatty acid core and a polar surface
What is the effect of pancreatic lipase on triacylglycerol?
It is degraded to monoacylglycerol and two fatty acids
What are the products of digestion of a cholesterol ester?
Cholesterol and free fatty acids
What are phospholipids hydrolysed to?
Fatty acid and a lysophospholipid
What is an enterocyte?
A cell of the intestinal lining
What does the products of lipid digestion form?
Mixed micelles with bile salts
What type of fatty acids do not require micelles for absorption?
Short and medium chain?
What is steatorrhea?
Lipid malabsorption
Why might someone get steatorrhea?
Defects in bile secretion (gall bladder removal), pancreatic function or intestinal cell uptake
What effect does steatorrhea have on poo?
FLOAT! and they are oily an smelly
What happens to absorbed dietary lipids?
Intestinal cells resynthesize them for export
What are the lipids packaged with?
apoB-48 which is a solubalising protein
What are the lipids packaged into after absorption?
Chlyomicrons
What happens to the chlyomicrons?
They are released into the lymph by exocytosis and then blood
When the chlyomicron reaches the tissue, what happens to the triacylglyceride in a chlyomicron?
It is hydrolysed to fatty acid and glycerol by lipoprotein lipase
Where is lipoprotein lipase found?
capillaries of skeletal muscles and adipose tissue
What happens to the fatty acids produced by break down of triacylglycerol by lipoprotein lipase?
Used for energy or re-esterified to TAG for storgage
What are chlyomicrons depleted of TAG called?
Chlyomicron remnants - they go to the liver
What does the liver use glycerol for?
produces glycerol 3 phosphate, used in glycolysis and glucogenesis
How are triacylglycerols stored in adipose cells?
Stored as droplets that constitute the depot fat
What is the most efficient storage form of fuel?
triacylglycerols
What releases the fatty acids from stored TAG?
HSL, hormone sensitive lipase
What activates HSL?
Phosphorylation in response to epinephrine
What might promote dephosphorylation (deactivation) of lipase?
High plasma glucose and insulin
What does free fatty acid complex with in order to be transported through the blood?
Serum albumin
What is the most abundant plasma protein?
Serum albumen
What is the fatty acid- serum albumen complex carried by?
Lipoproteins
What cannot be transported in the blood or lymph as free molecules?
TAGs cholesterol esters
What makes up the hydrophobic core of a lipoprotein?
TAGs, cholesterol esters
What makes up the hydrophilic surfaces of a lipoprotein?
Unesterified cholesterol, phospholipids apiloproteins -B100 eg
What is the order of lipoproteins in order of increasing density?
Chlyomicrons, VLDL, LDL HDL
Which type of lipoproteins are rich in TAG?
Chlyomicrons and VLDL
Which type of lipoproteins are rich in Cholesterol?
HDL, LDL
Which type of lipoproteins are rich in proteins?
HDL
Where do chlyomicrons transport TAG?
Intestine to tissues
Where do VLDL transport TAG?
Liver to tissue
Where do LDL transport cholesterol?
Extrahepatic tissue
Where do HDL transport cholesterol?
Tissue to liver for elimination
What is the effect of too much LDL?
Atherosclerosis - lipid develops into fatty streaks and plaque within the artery.
