LECTURE 15 - DIETARY LIPIDS Flashcards
what is the definition of lipids?
heterogeneous group of biological compounds including fats, oils, steroids, waxed, relatively insoluble in water
what are common properties of lipids
relatively insoluble in water
soluble in nonpolar solvents (ether or chloroform)
what are functions of lipids
energy storage
dietary compounds bc of their high energy
structural components of membranes
thermal insulators in subcutaneous tissues
signalling molecules
hormone precursors
what structures do lipids form
micelles
polar heads face the polar core and lipids face the inside
in what locations are lipids present and what are they involved in
plasma membrane: phospholipid remodelling
mitochondrion: beta oxidation
ER: phospholipid and neutral lipid biosynthesis
lipid storage droplets:lipolysis
cytosol: FA synthesis
atherosclerosis
what are purified lipids
triacylglycerol
comes from olive oil
neutral lipid
what are cellular lipids
lipid droplets:
triacylglycerol
cholesteryl esters
-> neutral lipids
membrane lipids:
phospholipids
sphingolipids
glycolipids
cholesterol
-> amphipatic
what are the different elements that help in the absorption of dietary lipids?
bile salts generate micelles
pancreatic lipase breaks down triglycerides
i-FABP(intestinal) (Fatty acid binding protein) helps to carry fatty acids inside the enterocyte
how do lipids get from the diet to the blood?
- mucosa
absorption of FA+MAG
absorption of sterole - ER: chylomicron assembly
triacylglyceride
cholesterol
ApoB48 - chylomicron secretion to circulation
where are free fatty acids located in the cell?
mitochondrion and cytosol
structure of a fatty acid
difference between saturated and unsaturated in the membrane
what is the relationship between number of carbons and melting point
number of carbons goes up, melting point also goes up
what is the relationship between unsaturation and melting point?
more unsaturated=melting point goes down
what is the difference between cis and trans fatty acids?
how are trans fats produced?
produced by partial hydrogenation of vegetable oils in the food industry
converts some cis double bonds to the trans configuration
why do trans fats have higher melting points
they pack more regularly
what does trans fats consumption increase
increases risk of cardiovascular disease
nomenclature of unsaturated fatty acids
where are branched chain fatty acids found?
present in bacteria and some ruminants (dairy products)
which branched fatty acids are present in humans?
very uncommon but we have two
pristanic acid
phytanic acid
what reactions do branch fatty acids undergo?
alpha oxidation (peroxisome) instead of beta oxidation (in mitochondrion)
what are isoprenoids?
similar to fatty acid with some branching but a different type of molecule
what are characteristics of triglycerides
100% hydrophobic
excellent way to package and transport fatty acids
present in many foods
structure of triglycerol?
three acyl chains + 1 glycerol
